Techwizz/kernel-fxtec-pro1x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Merge branch 'core/urgent' into core/rcu

Browse source 
Merge reason: new patches to be queued up depend on:

   ef631b0: rcu: Make hierarchical RCU less IPI-happy

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-04-14 11:32:23 +02:00
commit 05cfbd66d0
4394 changed files with 537682 additions and 148178 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
CREDITS
View file

@ -495,6 +495,11 @@ S: Kopmansg 2
S: 411 13 Goteborg
S: Sweden
N: Paul Bristow
E: paul@paulbristow.net
W: http://paulbristow.net/linux/idefloppy.html
D: Maintainer of IDE/ATAPI floppy driver
N: Dominik Brodowski
E: linux@brodo.de
W: http://www.brodo.de/
@ -1407,8 +1412,8 @@ P: 1024D/77D4FC9B F5C5 1C20 1DFC DEC3 3107 54A4 2332 ADFC 77D4 FC9B
D: National Language Support
D: Linux Internationalization Project
D: German Localization for Linux and GNU software
S: Kriemhildring 12a
S: 65795 Hattersheim am Main
S: Auf der Fittel 18
S: 53347 Alfter
S: Germany
N: Christoph Hellwig
@ -2642,6 +2647,10 @@ S: C/ Mieses 20, 9-B
S: Valladolid 47009
S: Spain
N: Gadi Oxman
E: gadio@netvision.net.il
D: Original author and maintainer of IDE/ATAPI floppy/tape drivers
N: Greg Page
E: gpage@sovereign.org
D: IPX development and support
@ -3571,6 +3580,12 @@ N: Dirk Verworner
D: Co-author of German book ``Linux-Kernel-Programmierung''
D: Co-founder of Berlin Linux User Group
N: Riku Voipio
E: riku.voipio@iki.fi
D: Author of PCA9532 LED and Fintek f75375s hwmon driver
D: Some random ARM board patches
S: Finland
N: Patrick Volkerding
E: volkerdi@ftp.cdrom.com
D: Produced the Slackware distribution, updated the SVGAlib

4
Documentation/00-INDEX
View file

@ -86,6 +86,8 @@ cachetlb.txt
- describes the cache/TLB flushing interfaces Linux uses.
cdrom/
- directory with information on the CD-ROM drivers that Linux has.
cgroups/
- cgroups features, including cpusets and memory controller.
connector/
- docs on the netlink based userspace<->kernel space communication mod.
console/
@ -98,8 +100,6 @@ cpu-load.txt
- document describing how CPU load statistics are collected.
cpuidle/
- info on CPU_IDLE, CPU idle state management subsystem.
cpusets.txt
- documents the cpusets feature; assign CPUs and Mem to a set of tasks.
cputopology.txt
- documentation on how CPU topology info is exported via sysfs.
cris/

71
Documentation/ABI/testing/debugfs-kmemtrace Normal file
View file

@ -0,0 +1,71 @@
What: /sys/kernel/debug/kmemtrace/
Date: July 2008
Contact: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Description:
In kmemtrace-enabled kernels, the following files are created:
/sys/kernel/debug/kmemtrace/
cpu<n> (0400) Per-CPU tracing data, see below. (binary)
total_overruns (0400) Total number of bytes which were dropped from
cpu<n> files because of full buffer condition,
non-binary. (text)
abi_version (0400) Kernel's kmemtrace ABI version. (text)
Each per-CPU file should be read according to the relay interface. That is,
the reader should set affinity to that specific CPU and, as currently done by
the userspace application (though there are other methods), use poll() with
an infinite timeout before every read(). Otherwise, erroneous data may be
read. The binary data has the following _core_ format:
Event ID (1 byte) Unsigned integer, one of:
0 - represents an allocation (KMEMTRACE_EVENT_ALLOC)
1 - represents a freeing of previously allocated memory
(KMEMTRACE_EVENT_FREE)
Type ID (1 byte) Unsigned integer, one of:
0 - this is a kmalloc() / kfree()
1 - this is a kmem_cache_alloc() / kmem_cache_free()
2 - this is a __get_free_pages() et al.
Event size (2 bytes) Unsigned integer representing the
size of this event. Used to extend
kmemtrace. Discard the bytes you
don't know about.
Sequence number (4 bytes) Signed integer used to reorder data
logged on SMP machines. Wraparound
must be taken into account, although
it is unlikely.
Caller address (8 bytes) Return address to the caller.
Pointer to mem (8 bytes) Pointer to target memory area. Can be
NULL, but not all such calls might be
recorded.
In case of KMEMTRACE_EVENT_ALLOC events, the next fields follow:
Requested bytes (8 bytes) Total number of requested bytes,
unsigned, must not be zero.
Allocated bytes (8 bytes) Total number of actually allocated
bytes, unsigned, must not be lower
than requested bytes.
Requested flags (4 bytes) GFP flags supplied by the caller.
Target CPU (4 bytes) Signed integer, valid for event id 1.
If equal to -1, target CPU is the same
as origin CPU, but the reverse might
not be true.
The data is made available in the same endianness the machine has.
Other event ids and type ids may be defined and added. Other fields may be
added by increasing event size, but see below for details.
Every modification to the ABI, including new id definitions, are followed
by bumping the ABI version by one.
Adding new data to the packet (features) is done at the end of the mandatory
data:
Feature size (2 byte)
Feature ID (1 byte)
Feature data (Feature size - 3 bytes)
Users:
kmemtrace-user - git://repo.or.cz/kmemtrace-user.git

6
Documentation/ABI/testing/debugfs-pktcdvd
View file

@ -1,4 +1,4 @@
What: /debug/pktcdvd/pktcdvd[0-7]
What: /sys/kernel/debug/pktcdvd/pktcdvd[0-7]
Date: Oct. 2006
KernelVersion: 2.6.20
Contact: Thomas Maier <balagi@justmail.de>
@ -10,10 +10,10 @@ debugfs interface
The pktcdvd module (packet writing driver) creates
these files in debugfs:
/debug/pktcdvd/pktcdvd[0-7]/
/sys/kernel/debug/pktcdvd/pktcdvd[0-7]/
info (0444) Lots of driver statistics and infos.
Example:
-------
cat /debug/pktcdvd/pktcdvd0/info
cat /sys/kernel/debug/pktcdvd/pktcdvd0/info

70
Documentation/ABI/testing/sysfs-bus-pci
View file

@ -41,6 +41,49 @@ Description:
for the device and attempt to bind to it. For example:
# echo "8086 10f5" > /sys/bus/pci/drivers/foo/new_id
What: /sys/bus/pci/drivers/.../remove_id
Date: February 2009
Contact: Chris Wright <chrisw@sous-sol.org>
Description:
Writing a device ID to this file will remove an ID
that was dynamically added via the new_id sysfs entry.
The format for the device ID is:
VVVV DDDD SVVV SDDD CCCC MMMM. That is Vendor ID, Device
ID, Subsystem Vendor ID, Subsystem Device ID, Class,
and Class Mask. The Vendor ID and Device ID fields are
required, the rest are optional. After successfully
removing an ID, the driver will no longer support the
device. This is useful to ensure auto probing won't
match the driver to the device. For example:
# echo "8086 10f5" > /sys/bus/pci/drivers/foo/remove_id
What: /sys/bus/pci/rescan
Date: January 2009
Contact: Linux PCI developers <linux-pci@vger.kernel.org>
Description:
Writing a non-zero value to this attribute will
force a rescan of all PCI buses in the system, and
re-discover previously removed devices.
Depends on CONFIG_HOTPLUG.
What: /sys/bus/pci/devices/.../remove
Date: January 2009
Contact: Linux PCI developers <linux-pci@vger.kernel.org>
Description:
Writing a non-zero value to this attribute will
hot-remove the PCI device and any of its children.
Depends on CONFIG_HOTPLUG.
What: /sys/bus/pci/devices/.../rescan
Date: January 2009
Contact: Linux PCI developers <linux-pci@vger.kernel.org>
Description:
Writing a non-zero value to this attribute will
force a rescan of the device's parent bus and all
child buses, and re-discover devices removed earlier
from this part of the device tree.
Depends on CONFIG_HOTPLUG.
What: /sys/bus/pci/devices/.../vpd
Date: February 2008
Contact: Ben Hutchings <bhutchings@solarflare.com>
@ -52,3 +95,30 @@ Description:
that some devices may have malformatted data. If the
underlying VPD has a writable section then the
corresponding section of this file will be writable.
What: /sys/bus/pci/devices/.../virtfnN
Date: March 2009
Contact: Yu Zhao <yu.zhao@intel.com>
Description:
This symbolic link appears when hardware supports the SR-IOV
capability and the Physical Function driver has enabled it.
The symbolic link points to the PCI device sysfs entry of the
Virtual Function whose index is N (0...MaxVFs-1).
What: /sys/bus/pci/devices/.../dep_link
Date: March 2009
Contact: Yu Zhao <yu.zhao@intel.com>
Description:
This symbolic link appears when hardware supports the SR-IOV
capability and the Physical Function driver has enabled it,
and this device has vendor specific dependencies with others.
The symbolic link points to the PCI device sysfs entry of
Physical Function this device depends on.
What: /sys/bus/pci/devices/.../physfn
Date: March 2009
Contact: Yu Zhao <yu.zhao@intel.com>
Description:
This symbolic link appears when a device is a Virtual Function.
The symbolic link points to the PCI device sysfs entry of the
Physical Function this device associates with.

57
Documentation/ABI/testing/sysfs-class-regulator
View file

@ -4,8 +4,8 @@ KernelVersion: 2.6.26
Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Some regulator directories will contain a field called
state. This reports the regulator enable status, for
regulators which can report that value.
state. This reports the regulator enable control, for
regulators which can report that input value.
This will be one of the following strings:
@ -14,16 +14,54 @@ Description:
'unknown'
'enabled' means the regulator output is ON and is supplying
power to the system.
power to the system (assuming no error prevents it).
'disabled' means the regulator output is OFF and is not
supplying power to the system..
supplying power to the system (unless some non-Linux
control has enabled it).
'unknown' means software cannot determine the state, or
the reported state is invalid.
NOTE: this field can be used in conjunction with microvolts
and microamps to determine regulator output levels.
or microamps to determine configured regulator output levels.
What: /sys/class/regulator/.../status
Description:
Some regulator directories will contain a field called
"status". This reports the current regulator status, for
regulators which can report that output value.
This will be one of the following strings:
off
on
error
fast
normal
idle
standby
"off" means the regulator is not supplying power to the
system.
"on" means the regulator is supplying power to the system,
and the regulator can't report a detailed operation mode.
"error" indicates an out-of-regulation status such as being
disabled due to thermal shutdown, or voltage being unstable
because of problems with the input power supply.
"fast", "normal", "idle", and "standby" are all detailed
regulator operation modes (described elsewhere). They
imply "on", but provide more detail.
Note that regulator status is a function of many inputs,
not limited to control inputs from Linux. For example,
the actual load presented may trigger "error" status; or
a regulator may be enabled by another user, even though
Linux did not enable it.
What: /sys/class/regulator/.../type
@ -58,7 +96,7 @@ Description:
Some regulator directories will contain a field called
microvolts. This holds the regulator output voltage setting
measured in microvolts (i.e. E-6 Volts), for regulators
which can report that voltage.
which can report the control input for voltage.
NOTE: This value should not be used to determine the regulator
output voltage level as this value is the same regardless of
@ -73,7 +111,7 @@ Description:
Some regulator directories will contain a field called
microamps. This holds the regulator output current limit
setting measured in microamps (i.e. E-6 Amps), for regulators
which can report that current.
which can report the control input for a current limit.
NOTE: This value should not be used to determine the regulator
output current level as this value is the same regardless of
@ -87,7 +125,7 @@ Contact: Liam Girdwood <lrg@slimlogic.co.uk>
Description:
Some regulator directories will contain a field called
opmode. This holds the current regulator operating mode,
for regulators which can report it.
for regulators which can report that control input value.
The opmode value can be one of the following strings:
@ -101,7 +139,8 @@ Description:
NOTE: This value should not be used to determine the regulator
output operating mode as this value is the same regardless of
whether the regulator is enabled or disabled.
whether the regulator is enabled or disabled. A "status"
attribute may be available to determine the actual mode.
What: /sys/class/regulator/.../min_microvolts

81
Documentation/ABI/testing/sysfs-fs-ext4 Normal file
View file

@ -0,0 +1,81 @@
What: /sys/fs/ext4/<disk>/mb_stats
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Controls whether the multiblock allocator should
collect statistics, which are shown during the unmount.
1 means to collect statistics, 0 means not to collect
statistics
What: /sys/fs/ext4/<disk>/mb_group_prealloc
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The multiblock allocator will round up allocation
requests to a multiple of this tuning parameter if the
stripe size is not set in the ext4 superblock
What: /sys/fs/ext4/<disk>/mb_max_to_scan
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The maximum number of extents the multiblock allocator
will search to find the best extent
What: /sys/fs/ext4/<disk>/mb_min_to_scan
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The minimum number of extents the multiblock allocator
will search to find the best extent
What: /sys/fs/ext4/<disk>/mb_order2_req
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Tuning parameter which controls the minimum size for
requests (as a power of 2) where the buddy cache is
used
What: /sys/fs/ext4/<disk>/mb_stream_req
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Files which have fewer blocks than this tunable
parameter will have their blocks allocated out of a
block group specific preallocation pool, so that small
files are packed closely together. Each large file
will have its blocks allocated out of its own unique
preallocation pool.
What: /sys/fs/ext4/<disk>/inode_readahead
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Tuning parameter which controls the maximum number of
inode table blocks that ext4's inode table readahead
algorithm will pre-read into the buffer cache
What: /sys/fs/ext4/<disk>/delayed_allocation_blocks
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of blocks
that are dirty in the page cache, but which do not
have their location in the filesystem allocated yet.
What: /sys/fs/ext4/<disk>/lifetime_write_kbytes
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of kilobytes
of data that have been written to this filesystem since it was
created.
What: /sys/fs/ext4/<disk>/session_write_kbytes
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of
kilobytes of data that have been written to this
filesystem since it was mounted.

18
Documentation/DMA-mapping.txt
View file

@ -136,7 +136,7 @@ exactly why.
The standard 32-bit addressing PCI device would do something like
this:
if (pci_set_dma_mask(pdev, DMA_32BIT_MASK)) {
if (pci_set_dma_mask(pdev, DMA_BIT_MASK(32))) {
printk(KERN_WARNING
"mydev: No suitable DMA available.\n");
goto ignore_this_device;
@ -155,9 +155,9 @@ all 64-bits when accessing streaming DMA:
int using_dac;
if (!pci_set_dma_mask(pdev, DMA_64BIT_MASK)) {
if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
using_dac = 1;
} else if (!pci_set_dma_mask(pdev, DMA_32BIT_MASK)) {
} else if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(32))) {
using_dac = 0;
} else {
printk(KERN_WARNING
@ -170,14 +170,14 @@ the case would look like this:
int using_dac, consistent_using_dac;
if (!pci_set_dma_mask(pdev, DMA_64BIT_MASK)) {
if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
using_dac = 1;
consistent_using_dac = 1;
pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK);
} else if (!pci_set_dma_mask(pdev, DMA_32BIT_MASK)) {
pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64));
} else if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(32))) {
using_dac = 0;
consistent_using_dac = 0;
pci_set_consistent_dma_mask(pdev, DMA_32BIT_MASK);
pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
} else {
printk(KERN_WARNING
"mydev: No suitable DMA available.\n");
@ -192,7 +192,7 @@ check the return value from pci_set_consistent_dma_mask().
Finally, if your device can only drive the low 24-bits of
address during PCI bus mastering you might do something like:
if (pci_set_dma_mask(pdev, DMA_24BIT_MASK)) {
if (pci_set_dma_mask(pdev, DMA_BIT_MASK(24))) {
printk(KERN_WARNING
"mydev: 24-bit DMA addressing not available.\n");
goto ignore_this_device;
@ -213,7 +213,7 @@ most specific mask.
Here is pseudo-code showing how this might be done:
#define PLAYBACK_ADDRESS_BITS DMA_32BIT_MASK
#define PLAYBACK_ADDRESS_BITS DMA_BIT_MASK(32)
#define RECORD_ADDRESS_BITS 0x00ffffff
struct my_sound_card *card;

4
Documentation/DocBook/.gitignore vendored
View file

@ -4,3 +4,7 @@
*.html
*.9.gz
*.9
*.aux
*.dvi
*.log
*.out

11
Documentation/DocBook/Makefile
View file

@ -31,7 +31,7 @@ PS_METHOD = $(prefer-db2x)
###
# The targets that may be used.
PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs
PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs cleandocs
BOOKS := $(addprefix $(obj)/,$(DOCBOOKS))
xmldocs: $(BOOKS)
@ -213,11 +213,12 @@ silent_gen_xml = :
dochelp:
@echo ' Linux kernel internal documentation in different formats:'
@echo ' htmldocs - HTML'
@echo ' installmandocs - install man pages generated by mandocs'
@echo ' mandocs - man pages'
@echo ' pdfdocs - PDF'
@echo ' psdocs - Postscript'
@echo ' xmldocs - XML DocBook'
@echo ' mandocs - man pages'
@echo ' installmandocs - install man pages generated by mandocs'
@echo ' cleandocs - clean all generated DocBook files'
###
# Temporary files left by various tools
@ -235,6 +236,10 @@ clean-files := $(DOCBOOKS) \
clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man
cleandocs:
$(Q)rm -f $(call objectify, $(clean-files))
$(Q)rm -rf $(call objectify, $(clean-dirs))
# Declare the contents of the .PHONY variable as phony. We keep that
# information in a variable se we can use it in if_changed and friends.

3
Documentation/DocBook/kernel-api.tmpl
View file

@ -199,6 +199,7 @@ X!Edrivers/pci/hotplug.c
-->
!Edrivers/pci/probe.c
!Edrivers/pci/rom.c
!Edrivers/pci/iov.c
</sect1>
<sect1><title>PCI Hotplug Support Library</title>
!Edrivers/pci/hotplug/pci_hotplug_core.c
@ -258,7 +259,7 @@ X!Earch/x86/kernel/mca_32.c
!Eblock/blk-tag.c
!Iblock/blk-tag.c
!Eblock/blk-integrity.c
!Iblock/blktrace.c
!Ikernel/trace/blktrace.c
!Iblock/genhd.c
!Eblock/genhd.c
</chapter>

9
Documentation/DocBook/procfs_example.c
View file

@ -117,9 +117,6 @@ static int __init init_procfs_example(void)
rv = -ENOMEM;
goto out;
}
example_dir->owner = THIS_MODULE;
/* create jiffies using convenience function */
jiffies_file = create_proc_read_entry("jiffies",
0444, example_dir,
@ -130,8 +127,6 @@ static int __init init_procfs_example(void)
goto no_jiffies;
}
jiffies_file->owner = THIS_MODULE;
/* create foo and bar files using same callback
* functions
*/
@ -146,7 +141,6 @@ static int __init init_procfs_example(void)
foo_file->data = &foo_data;
foo_file->read_proc = proc_read_foobar;
foo_file->write_proc = proc_write_foobar;
foo_file->owner = THIS_MODULE;
bar_file = create_proc_entry("bar", 0644, example_dir);
if(bar_file == NULL) {
@ -159,7 +153,6 @@ static int __init init_procfs_example(void)
bar_file->data = &bar_data;
bar_file->read_proc = proc_read_foobar;
bar_file->write_proc = proc_write_foobar;
bar_file->owner = THIS_MODULE;
/* create symlink */
symlink = proc_symlink("jiffies_too", example_dir,
@ -169,8 +162,6 @@ static int __init init_procfs_example(void)
goto no_symlink;
}
symlink->owner = THIS_MODULE;
/* everything OK */
printk(KERN_INFO "%s %s initialised\n",
MODULE_NAME, MODULE_VERS);

8
Documentation/DocBook/writing-an-alsa-driver.tmpl
View file

@ -1137,8 +1137,8 @@
if (err < 0)
return err;
/* check PCI availability (28bit DMA) */
if (pci_set_dma_mask(pci, DMA_28BIT_MASK) < 0 ||
pci_set_consistent_dma_mask(pci, DMA_28BIT_MASK) < 0) {
if (pci_set_dma_mask(pci, DMA_BIT_MASK(28)) < 0 ||
pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(28)) < 0) {
printk(KERN_ERR "error to set 28bit mask DMA\n");
pci_disable_device(pci);
return -ENXIO;
@ -1252,8 +1252,8 @@
err = pci_enable_device(pci);
if (err < 0)
return err;
if (pci_set_dma_mask(pci, DMA_28BIT_MASK) < 0 ||
pci_set_consistent_dma_mask(pci, DMA_28BIT_MASK) < 0) {
if (pci_set_dma_mask(pci, DMA_BIT_MASK(28)) < 0 ||
pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(28)) < 0) {
printk(KERN_ERR "error to set 28bit mask DMA\n");
pci_disable_device(pci);
return -ENXIO;

702
Documentation/PCI/MSI-HOWTO.txt
View file

@ -4,506 +4,356 @@
Revised Feb 12, 2004 by Martine Silbermann
email: Martine.Silbermann@hp.com
Revised Jun 25, 2004 by Tom L Nguyen
Revised Jul 9, 2008 by Matthew Wilcox <willy@linux.intel.com>
Copyright 2003, 2008 Intel Corporation
1. About this guide
This guide describes the basics of Message Signaled Interrupts (MSI),
the advantages of using MSI over traditional interrupt mechanisms,
and how to enable your driver to use MSI or MSI-X. Also included is
a Frequently Asked Questions (FAQ) section.
This guide describes the basics of Message Signaled Interrupts (MSIs),
the advantages of using MSI over traditional interrupt mechanisms, how
to change your driver to use MSI or MSI-X and some basic diagnostics to
try if a device doesn't support MSIs.
1.1 Terminology
PCI devices can be single-function or multi-function. In either case,
when this text talks about enabling or disabling MSI on a "device
function," it is referring to one specific PCI device and function and
not to all functions on a PCI device (unless the PCI device has only
one function).
2. What are MSIs?
2. Copyright 2003 Intel Corporation
A Message Signaled Interrupt is a write from the device to a special
address which causes an interrupt to be received by the CPU.
3. What is MSI/MSI-X?
The MSI capability was first specified in PCI 2.2 and was later enhanced
in PCI 3.0 to allow each interrupt to be masked individually. The MSI-X
capability was also introduced with PCI 3.0. It supports more interrupts
per device than MSI and allows interrupts to be independently configured.
Message Signaled Interrupt (MSI), as described in the PCI Local Bus
Specification Revision 2.3 or later, is an optional feature, and a
required feature for PCI Express devices. MSI enables a device function
to request service by sending an Inbound Memory Write on its PCI bus to
the FSB as a Message Signal Interrupt transaction. Because MSI is
generated in the form of a Memory Write, all transaction conditions,
such as a Retry, Master-Abort, Target-Abort or normal completion, are
supported.
Devices may support both MSI and MSI-X, but only one can be enabled at
a time.
A PCI device that supports MSI must also support pin IRQ assertion
interrupt mechanism to provide backward compatibility for systems that
do not support MSI. In systems which support MSI, the bus driver is
responsible for initializing the message address and message data of
the device function's MSI/MSI-X capability structure during device
initial configuration.
An MSI capable device function indicates MSI support by implementing
the MSI/MSI-X capability structure in its PCI capability list. The
device function may implement both the MSI capability structure and
the MSI-X capability structure; however, the bus driver should not
enable both.
3. Why use MSIs?
The MSI capability structure contains Message Control register,
Message Address register and Message Data register. These registers
provide the bus driver control over MSI. The Message Control register
indicates the MSI capability supported by the device. The Message
Address register specifies the target address and the Message Data
register specifies the characteristics of the message. To request
service, the device function writes the content of the Message Data
register to the target address. The device and its software driver
are prohibited from writing to these registers.
There are three reasons why using MSIs can give an advantage over
traditional pin-based interrupts.
The MSI-X capability structure is an optional extension to MSI. It
uses an independent and separate capability structure. There are
some key advantages to implementing the MSI-X capability structure
over the MSI capability structure as described below.
Pin-based PCI interrupts are often shared amongst several devices.
To support this, the kernel must call each interrupt handler associated
with an interrupt, which leads to reduced performance for the system as
a whole. MSIs are never shared, so this problem cannot arise.
- Support a larger maximum number of vectors per function.
When a device writes data to memory, then raises a pin-based interrupt,
it is possible that the interrupt may arrive before all the data has
arrived in memory (this becomes more likely with devices behind PCI-PCI
bridges). In order to ensure that all the data has arrived in memory,
the interrupt handler must read a register on the device which raised
the interrupt. PCI transaction ordering rules require that all the data
arrives in memory before the value can be returned from the register.
Using MSIs avoids this problem as the interrupt-generating write cannot
pass the data writes, so by the time the interrupt is raised, the driver
knows that all the data has arrived in memory.
- Provide the ability for system software to configure
each vector with an independent message address and message
data, specified by a table that resides in Memory Space.
PCI devices can only support a single pin-based interrupt per function.
Often drivers have to query the device to find out what event has
occurred, slowing down interrupt handling for the common case. With
MSIs, a device can support more interrupts, allowing each interrupt
to be specialised to a different purpose. One possible design gives
infrequent conditions (such as errors) their own interrupt which allows
the driver to handle the normal interrupt handling path more efficiently.
Other possible designs include giving one interrupt to each packet queue
in a network card or each port in a storage controller.
- MSI and MSI-X both support per-vector masking. Per-vector
masking is an optional extension of MSI but a required
feature for MSI-X. Per-vector masking provides the kernel the
ability to mask/unmask a single MSI while running its
interrupt service routine. If per-vector masking is
not supported, then the device driver should provide the
hardware/software synchronization to ensure that the device
generates MSI when the driver wants it to do so.
4. Why use MSI?
4. How to use MSIs
As a benefit to the simplification of board design, MSI allows board
designers to remove out-of-band interrupt routing. MSI is another
step towards a legacy-free environment.
PCI devices are initialised to use pin-based interrupts. The device
driver has to set up the device to use MSI or MSI-X. Not all machines
support MSIs correctly, and for those machines, the APIs described below
will simply fail and the device will continue to use pin-based interrupts.
Due to increasing pressure on chipset and processor packages to
reduce pin count, the need for interrupt pins is expected to
diminish over time. Devices, due to pin constraints, may implement
messages to increase performance.
4.1 Include kernel support for MSIs
PCI Express endpoints uses INTx emulation (in-band messages) instead
of IRQ pin assertion. Using INTx emulation requires interrupt
sharing among devices connected to the same node (PCI bridge) while
MSI is unique (non-shared) and does not require BIOS configuration
support. As a result, the PCI Express technology requires MSI
support for better interrupt performance.
To support MSI or MSI-X, the kernel must be built with the CONFIG_PCI_MSI
option enabled. This option is only available on some architectures,
and it may depend on some other options also being set. For example,
on x86, you must also enable X86_UP_APIC or SMP in order to see the
CONFIG_PCI_MSI option.
Using MSI enables the device functions to support two or more
vectors, which can be configured to target different CPUs to
increase scalability.
4.2 Using MSI
5. Configuring a driver to use MSI/MSI-X
Most of the hard work is done for the driver in the PCI layer. It simply
has to request that the PCI layer set up the MSI capability for this
device.
By default, the kernel will not enable MSI/MSI-X on all devices that
support this capability. The CONFIG_PCI_MSI kernel option
must be selected to enable MSI/MSI-X support.
5.1 Including MSI/MSI-X support into the kernel
To allow MSI/MSI-X capable device drivers to selectively enable
MSI/MSI-X (using pci_enable_msi()/pci_enable_msix() as described
below), the VECTOR based scheme needs to be enabled by setting
CONFIG_PCI_MSI during kernel config.
Since the target of the inbound message is the local APIC, providing
CONFIG_X86_LOCAL_APIC must be enabled as well as CONFIG_PCI_MSI.
5.2 Configuring for MSI support
Due to the non-contiguous fashion in vector assignment of the
existing Linux kernel, this version does not support multiple
messages regardless of a device function is capable of supporting
more than one vector. To enable MSI on a device function's MSI
capability structure requires a device driver to call the function
pci_enable_msi() explicitly.
5.2.1 API pci_enable_msi
4.2.1 pci_enable_msi
int pci_enable_msi(struct pci_dev *dev)
With this new API, a device driver that wants to have MSI
enabled on its device function must call this API to enable MSI.
A successful call will initialize the MSI capability structure
with ONE vector, regardless of whether a device function is
capable of supporting multiple messages. This vector replaces the
pre-assigned dev->irq with a new MSI vector. To avoid a conflict
of the new assigned vector with existing pre-assigned vector requires
a device driver to call this API before calling request_irq().
A successful call will allocate ONE interrupt to the device, regardless
of how many MSIs the device supports. The device will be switched from
pin-based interrupt mode to MSI mode. The dev->irq number is changed
to a new number which represents the message signaled interrupt.
This function should be called before the driver calls request_irq()
since enabling MSIs disables the pin-based IRQ and the driver will not
receive interrupts on the old interrupt.
5.2.2 API pci_disable_msi
4.2.2 pci_enable_msi_block
int pci_enable_msi_block(struct pci_dev *dev, int count)
This variation on the above call allows a device driver to request multiple
MSIs. The MSI specification only allows interrupts to be allocated in
powers of two, up to a maximum of 2^5 (32).
If this function returns 0, it has succeeded in allocating at least as many
interrupts as the driver requested (it may have allocated more in order
to satisfy the power-of-two requirement). In this case, the function
enables MSI on this device and updates dev->irq to be the lowest of
the new interrupts assigned to it. The other interrupts assigned to
the device are in the range dev->irq to dev->irq + count - 1.
If this function returns a negative number, it indicates an error and
the driver should not attempt to request any more MSI interrupts for
this device. If this function returns a positive number, it will be
less than 'count' and indicate the number of interrupts that could have
been allocated. In neither case will the irq value have been
updated, nor will the device have been switched into MSI mode.
The device driver must decide what action to take if
pci_enable_msi_block() returns a value less than the number asked for.
Some devices can make use of fewer interrupts than the maximum they
request; in this case the driver should call pci_enable_msi_block()
again. Note that it is not guaranteed to succeed, even when the
'count' has been reduced to the value returned from a previous call to
pci_enable_msi_block(). This is because there are multiple constraints
on the number of vectors that can be allocated; pci_enable_msi_block()
will return as soon as it finds any constraint that doesn't allow the
call to succeed.
4.2.3 pci_disable_msi
void pci_disable_msi(struct pci_dev *dev)
This API should always be used to undo the effect of pci_enable_msi()
when a device driver is unloading. This API restores dev->irq with
the pre-assigned IOAPIC vector and switches a device's interrupt
mode to PCI pin-irq assertion/INTx emulation mode.
This function should be used to undo the effect of pci_enable_msi() or
pci_enable_msi_block(). Calling it restores dev->irq to the pin-based
interrupt number and frees the previously allocated message signaled
interrupt(s). The interrupt may subsequently be assigned to another
device, so drivers should not cache the value of dev->irq.
Note that a device driver should always call free_irq() on the MSI vector
that it has done request_irq() on before calling this API. Failure to do
so results in a BUG_ON() and a device will be left with MSI enabled and
leaks its vector.
A device driver must always call free_irq() on the interrupt(s)
for which it has called request_irq() before calling this function.
Failure to do so will result in a BUG_ON(), the device will be left with
MSI enabled and will leak its vector.
5.2.3 MSI mode vs. legacy mode diagram
4.3 Using MSI-X
The below diagram shows the events which switch the interrupt
mode on the MSI-capable device function between MSI mode and
PIN-IRQ assertion mode.
------------ pci_enable_msi ------------------------
| | <=============== | |
| MSI MODE | | PIN-IRQ ASSERTION MODE |
| | ===============> | |
------------ pci_disable_msi ------------------------
Figure 1. MSI Mode vs. Legacy Mode
In Figure 1, a device operates by default in legacy mode. Legacy
in this context means PCI pin-irq assertion or PCI-Express INTx
emulation. A successful MSI request (using pci_enable_msi()) switches
a device's interrupt mode to MSI mode. A pre-assigned IOAPIC vector
stored in dev->irq will be saved by the PCI subsystem and a new
assigned MSI vector will replace dev->irq.
To return back to its default mode, a device driver should always call
pci_disable_msi() to undo the effect of pci_enable_msi(). Note that a
device driver should always call free_irq() on the MSI vector it has
done request_irq() on before calling pci_disable_msi(). Failure to do
so results in a BUG_ON() and a device will be left with MSI enabled and
leaks its vector. Otherwise, the PCI subsystem restores a device's
dev->irq with a pre-assigned IOAPIC vector and marks the released
MSI vector as unused.
Once being marked as unused, there is no guarantee that the PCI
subsystem will reserve this MSI vector for a device. Depending on
the availability of current PCI vector resources and the number of
MSI/MSI-X requests from other drivers, this MSI may be re-assigned.
For the case where the PCI subsystem re-assigns this MSI vector to
another driver, a request to switch back to MSI mode may result
in being assigned a different MSI vector or a failure if no more
vectors are available.
5.3 Configuring for MSI-X support
Due to the ability of the system software to configure each vector of
the MSI-X capability structure with an independent message address
and message data, the non-contiguous fashion in vector assignment of
the existing Linux kernel has no impact on supporting multiple
messages on an MSI-X capable device functions. To enable MSI-X on
a device function's MSI-X capability structure requires its device
driver to call the function pci_enable_msix() explicitly.
The function pci_enable_msix(), once invoked, enables either
all or nothing, depending on the current availability of PCI vector
resources. If the PCI vector resources are available for the number
of vectors requested by a device driver, this function will configure
the MSI-X table of the MSI-X capability structure of a device with
requested messages. To emphasize this reason, for example, a device
may be capable for supporting the maximum of 32 vectors while its
software driver usually may request 4 vectors. It is recommended
that the device driver should call this function once during the
initialization phase of the device driver.
Unlike the function pci_enable_msi(), the function pci_enable_msix()
does not replace the pre-assigned IOAPIC dev->irq with a new MSI
vector because the PCI subsystem writes the 1:1 vector-to-entry mapping
into the field vector of each element contained in a second argument.
Note that the pre-assigned IOAPIC dev->irq is valid only if the device
operates in PIN-IRQ assertion mode. In MSI-X mode, any attempt at
using dev->irq by the device driver to request for interrupt service
may result in unpredictable behavior.
For each MSI-X vector granted, a device driver is responsible for calling
other functions like request_irq(), enable_irq(), etc. to enable
this vector with its corresponding interrupt service handler. It is
a device driver's choice to assign all vectors with the same
interrupt service handler or each vector with a unique interrupt
service handler.
5.3.1 Handling MMIO address space of MSI-X Table
The PCI 3.0 specification has implementation notes that MMIO address
space for a device's MSI-X structure should be isolated so that the
software system can set different pages for controlling accesses to the
MSI-X structure. The implementation of MSI support requires the PCI
subsystem, not a device driver, to maintain full control of the MSI-X
table/MSI-X PBA (Pending Bit Array) and MMIO address space of the MSI-X
table/MSI-X PBA. A device driver should not access the MMIO address
space of the MSI-X table/MSI-X PBA.
5.3.2 API pci_enable_msix
int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
This API enables a device driver to request the PCI subsystem
to enable MSI-X messages on its hardware device. Depending on
the availability of PCI vectors resources, the PCI subsystem enables
either all or none of the requested vectors.
Argument 'dev' points to the device (pci_dev) structure.
Argument 'entries' is a pointer to an array of msix_entry structs.
The number of entries is indicated in argument 'nvec'.
struct msix_entry is defined in /driver/pci/msi.h:
The MSI-X capability is much more flexible than the MSI capability.
It supports up to 2048 interrupts, each of which can be controlled
independently. To support this flexibility, drivers must use an array of
`struct msix_entry':
struct msix_entry {
u16 vector; /* kernel uses to write alloc vector */
u16 entry; /* driver uses to specify entry */
};
A device driver is responsible for initializing the field 'entry' of
each element with a unique entry supported by MSI-X table. Otherwise,
-EINVAL will be returned as a result. A successful return of zero
indicates the PCI subsystem completed initializing each of the requested
entries of the MSI-X table with message address and message data.
Last but not least, the PCI subsystem will write the 1:1
vector-to-entry mapping into the field 'vector' of each element. A
device driver is responsible for keeping track of allocated MSI-X
vectors in its internal data structure.
This allows for the device to use these interrupts in a sparse fashion;
for example it could use interrupts 3 and 1027 and allocate only a
two-element array. The driver is expected to fill in the 'entry' value
in each element of the array to indicate which entries it wants the kernel
to assign interrupts for. It is invalid to fill in two entries with the
same number.
A return of zero indicates that the number of MSI-X vectors was
successfully allocated. A return of greater than zero indicates
MSI-X vector shortage. Or a return of less than zero indicates
a failure. This failure may be a result of duplicate entries
specified in second argument, or a result of no available vector,
or a result of failing to initialize MSI-X table entries.
4.3.1 pci_enable_msix
5.3.3 API pci_disable_msix
int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
Calling this function asks the PCI subsystem to allocate 'nvec' MSIs.
The 'entries' argument is a pointer to an array of msix_entry structs
which should be at least 'nvec' entries in size. On success, the
function will return 0 and the device will have been switched into
MSI-X interrupt mode. The 'vector' elements in each entry will have
been filled in with the interrupt number. The driver should then call
request_irq() for each 'vector' that it decides to use.
If this function returns a negative number, it indicates an error and
the driver should not attempt to allocate any more MSI-X interrupts for
this device. If it returns a positive number, it indicates the maximum
number of interrupt vectors that could have been allocated. See example
below.
This function, in contrast with pci_enable_msi(), does not adjust
dev->irq. The device will not generate interrupts for this interrupt
number once MSI-X is enabled. The device driver is responsible for
keeping track of the interrupts assigned to the MSI-X vectors so it can
free them again later.
Device drivers should normally call this function once per device
during the initialization phase.
It is ideal if drivers can cope with a variable number of MSI-X interrupts,
there are many reasons why the platform may not be able to provide the
exact number a driver asks for.
A request loop to achieve that might look like:
static int foo_driver_enable_msix(struct foo_adapter *adapter, int nvec)
{
while (nvec >= FOO_DRIVER_MINIMUM_NVEC) {
rc = pci_enable_msix(adapter->pdev,
adapter->msix_entries, nvec);
if (rc > 0)
nvec = rc;
else
return rc;
}
return -ENOSPC;
}
4.3.2 pci_disable_msix
void pci_disable_msix(struct pci_dev *dev)
This API should always be used to undo the effect of pci_enable_msix()
when a device driver is unloading. Note that a device driver should
always call free_irq() on all MSI-X vectors it has done request_irq()
on before calling this API. Failure to do so results in a BUG_ON() and
a device will be left with MSI-X enabled and leaks its vectors.
This API should be used to undo the effect of pci_enable_msix(). It frees
the previously allocated message signaled interrupts. The interrupts may
subsequently be assigned to another device, so drivers should not cache
the value of the 'vector' elements over a call to pci_disable_msix().
5.3.4 MSI-X mode vs. legacy mode diagram
A device driver must always call free_irq() on the interrupt(s)
for which it has called request_irq() before calling this function.
Failure to do so will result in a BUG_ON(), the device will be left with
MSI enabled and will leak its vector.
The below diagram shows the events which switch the interrupt
mode on the MSI-X capable device function between MSI-X mode and
PIN-IRQ assertion mode (legacy).
4.3.3 The MSI-X Table
------------ pci_enable_msix(,,n) ------------------------
| | <=============== | |
| MSI-X MODE | | PIN-IRQ ASSERTION MODE |
| | ===============> | |
------------ pci_disable_msix ------------------------
The MSI-X capability specifies a BAR and offset within that BAR for the
MSI-X Table. This address is mapped by the PCI subsystem, and should not
be accessed directly by the device driver. If the driver wishes to
mask or unmask an interrupt, it should call disable_irq() / enable_irq().
Figure 2. MSI-X Mode vs. Legacy Mode
4.4 Handling devices implementing both MSI and MSI-X capabilities
In Figure 2, a device operates by default in legacy mode. A
successful MSI-X request (using pci_enable_msix()) switches a
device's interrupt mode to MSI-X mode. A pre-assigned IOAPIC vector
stored in dev->irq will be saved by the PCI subsystem; however,
unlike MSI mode, the PCI subsystem will not replace dev->irq with
assigned MSI-X vector because the PCI subsystem already writes the 1:1
vector-to-entry mapping into the field 'vector' of each element
specified in second argument.
If a device implements both MSI and MSI-X capabilities, it can
run in either MSI mode or MSI-X mode but not both simultaneously.
This is a requirement of the PCI spec, and it is enforced by the
PCI layer. Calling pci_enable_msi() when MSI-X is already enabled or
pci_enable_msix() when MSI is already enabled will result in an error.
If a device driver wishes to switch between MSI and MSI-X at runtime,
it must first quiesce the device, then switch it back to pin-interrupt
mode, before calling pci_enable_msi() or pci_enable_msix() and resuming
operation. This is not expected to be a common operation but may be
useful for debugging or testing during development.
To return back to its default mode, a device driver should always call
pci_disable_msix() to undo the effect of pci_enable_msix(). Note that
a device driver should always call free_irq() on all MSI-X vectors it
has done request_irq() on before calling pci_disable_msix(). Failure
to do so results in a BUG_ON() and a device will be left with MSI-X
enabled and leaks its vectors. Otherwise, the PCI subsystem switches a
device function's interrupt mode from MSI-X mode to legacy mode and
marks all allocated MSI-X vectors as unused.
4.5 Considerations when using MSIs
Once being marked as unused, there is no guarantee that the PCI
subsystem will reserve these MSI-X vectors for a device. Depending on
the availability of current PCI vector resources and the number of
MSI/MSI-X requests from other drivers, these MSI-X vectors may be
re-assigned.
4.5.1 Choosing between MSI-X and MSI
For the case where the PCI subsystem re-assigned these MSI-X vectors
to other drivers, a request to switch back to MSI-X mode may result
being assigned with another set of MSI-X vectors or a failure if no
more vectors are available.
If your device supports both MSI-X and MSI capabilities, you should use
the MSI-X facilities in preference to the MSI facilities. As mentioned
above, MSI-X supports any number of interrupts between 1 and 2048.
In constrast, MSI is restricted to a maximum of 32 interrupts (and
must be a power of two). In addition, the MSI interrupt vectors must
be allocated consecutively, so the system may not be able to allocate
as many vectors for MSI as it could for MSI-X. On some platforms, MSI
interrupts must all be targetted at the same set of CPUs whereas MSI-X
interrupts can all be targetted at different CPUs.
5.4 Handling function implementing both MSI and MSI-X capabilities
4.5.2 Spinlocks
For the case where a function implements both MSI and MSI-X
capabilities, the PCI subsystem enables a device to run either in MSI
mode or MSI-X mode but not both. A device driver determines whether it
wants MSI or MSI-X enabled on its hardware device. Once a device
driver requests for MSI, for example, it is prohibited from requesting
MSI-X; in other words, a device driver is not permitted to ping-pong
between MSI mod MSI-X mode during a run-time.
Most device drivers have a per-device spinlock which is taken in the
interrupt handler. With pin-based interrupts or a single MSI, it is not
necessary to disable interrupts (Linux guarantees the same interrupt will
not be re-entered). If a device uses multiple interrupts, the driver
must disable interrupts while the lock is held. If the device sends
a different interrupt, the driver will deadlock trying to recursively
acquire the spinlock.
5.5 Hardware requirements for MSI/MSI-X support
There are two solutions. The first is to take the lock with
spin_lock_irqsave() or spin_lock_irq() (see
Documentation/DocBook/kernel-locking). The second is to specify
IRQF_DISABLED to request_irq() so that the kernel runs the entire
interrupt routine with interrupts disabled.
MSI/MSI-X support requires support from both system hardware and
individual hardware device functions.
If your MSI interrupt routine does not hold the lock for the whole time
it is running, the first solution may be best. The second solution is
normally preferred as it avoids making two transitions from interrupt
disabled to enabled and back again.
5.5.1 Required x86 hardware support
4.6 How to tell whether MSI/MSI-X is enabled on a device
Since the target of MSI address is the local APIC CPU, enabling
MSI/MSI-X support in the Linux kernel is dependent on whether existing
system hardware supports local APIC. Users should verify that their
system supports local APIC operation by testing that it runs when
CONFIG_X86_LOCAL_APIC=y.
Using 'lspci -v' (as root) may show some devices with "MSI", "Message
Signalled Interrupts" or "MSI-X" capabilities. Each of these capabilities
has an 'Enable' flag which will be followed with either "+" (enabled)
or "-" (disabled).
In SMP environment, CONFIG_X86_LOCAL_APIC is automatically set;
however, in UP environment, users must manually set
CONFIG_X86_LOCAL_APIC. Once CONFIG_X86_LOCAL_APIC=y, setting
CONFIG_PCI_MSI enables the VECTOR based scheme and the option for
MSI-capable device drivers to selectively enable MSI/MSI-X.
Note that CONFIG_X86_IO_APIC setting is irrelevant because MSI/MSI-X
vector is allocated new during runtime and MSI/MSI-X support does not
depend on BIOS support. This key independency enables MSI/MSI-X
support on future IOxAPIC free platforms.
5. MSI quirks
5.5.2 Device hardware support
Several PCI chipsets or devices are known not to support MSIs.
The PCI stack provides three ways to disable MSIs:
The hardware device function supports MSI by indicating the
MSI/MSI-X capability structure on its PCI capability list. By
default, this capability structure will not be initialized by
the kernel to enable MSI during the system boot. In other words,
the device function is running on its default pin assertion mode.
Note that in many cases the hardware supporting MSI have bugs,
which may result in system hangs. The software driver of specific
MSI-capable hardware is responsible for deciding whether to call
pci_enable_msi or not. A return of zero indicates the kernel
successfully initialized the MSI/MSI-X capability structure of the
device function. The device function is now running on MSI/MSI-X mode.
1. globally
2. on all devices behind a specific bridge
3. on a single device
5.6 How to tell whether MSI/MSI-X is enabled on device function
5.1. Disabling MSIs globally
At the driver level, a return of zero from the function call of
pci_enable_msi()/pci_enable_msix() indicates to a device driver that
its device function is initialized successfully and ready to run in
MSI/MSI-X mode.
Some host chipsets simply don't support MSIs properly. If we're
lucky, the manufacturer knows this and has indicated it in the ACPI
FADT table. In this case, Linux will automatically disable MSIs.
Some boards don't include this information in the table and so we have
to detect them ourselves. The complete list of these is found near the
quirk_disable_all_msi() function in drivers/pci/quirks.c.
At the user level, users can use the command 'cat /proc/interrupts'
to display the vectors allocated for devices and their interrupt
MSI/MSI-X modes ("PCI-MSI"/"PCI-MSI-X"). Below shows MSI mode is
enabled on a SCSI Adaptec 39320D Ultra320 controller.
If you have a board which has problems with MSIs, you can pass pci=nomsi
on the kernel command line to disable MSIs on all devices. It would be
in your best interests to report the problem to linux-pci@vger.kernel.org
including a full 'lspci -v' so we can add the quirks to the kernel.
CPU0 CPU1
0: 324639 0 IO-APIC-edge timer
1: 1186 0 IO-APIC-edge i8042
2: 0 0 XT-PIC cascade
12: 2797 0 IO-APIC-edge i8042
14: 6543 0 IO-APIC-edge ide0
15: 1 0 IO-APIC-edge ide1
169: 0 0 IO-APIC-level uhci-hcd
185: 0 0 IO-APIC-level uhci-hcd
193: 138 10 PCI-MSI aic79xx
201: 30 0 PCI-MSI aic79xx
225: 30 0 IO-APIC-level aic7xxx
233: 30 0 IO-APIC-level aic7xxx
NMI: 0 0
LOC: 324553 325068
ERR: 0
MIS: 0
5.2. Disabling MSIs below a bridge
6. MSI quirks
Some PCI bridges are not able to route MSIs between busses properly.
In this case, MSIs must be disabled on all devices behind the bridge.
Several PCI chipsets or devices are known to not support MSI.
The PCI stack provides 3 possible levels of MSI disabling:
* on a single device
* on all devices behind a specific bridge
* globally
Some bridges allow you to enable MSIs by changing some bits in their
PCI configuration space (especially the Hypertransport chipsets such
as the nVidia nForce and Serverworks HT2000). As with host chipsets,
Linux mostly knows about them and automatically enables MSIs if it can.
If you have a bridge which Linux doesn't yet know about, you can enable
MSIs in configuration space using whatever method you know works, then
enable MSIs on that bridge by doing:
6.1. Disabling MSI on a single device
echo 1 > /sys/bus/pci/devices/$bridge/msi_bus
Under some circumstances it might be required to disable MSI on a
single device. This may be achieved by either not calling pci_enable_msi()
or all, or setting the pci_dev->no_msi flag before (most of the time
in a quirk).
where $bridge is the PCI address of the bridge you've enabled (eg
0000:00:0e.0).
6.2. Disabling MSI below a bridge
To disable MSIs, echo 0 instead of 1. Changing this value should be
done with caution as it can break interrupt handling for all devices
below this bridge.
The vast majority of MSI quirks are required by PCI bridges not
being able to route MSI between busses. In this case, MSI have to be
disabled on all devices behind this bridge. It is achieves by setting
the PCI_BUS_FLAGS_NO_MSI flag in the pci_bus->bus_flags of the bridge
subordinate bus. There is no need to set the same flag on bridges that
are below the broken bridge. When pci_enable_msi() is called to enable
MSI on a device, pci_msi_supported() takes care of checking the NO_MSI
flag in all parent busses of the device.
Again, please notify linux-pci@vger.kernel.org of any bridges that need
special handling.
Some bridges actually support dynamic MSI support enabling/disabling
by changing some bits in their PCI configuration space (especially
the Hypertransport chipsets such as the nVidia nForce and Serverworks
HT2000). It may then be required to update the NO_MSI flag on the
corresponding devices in the sysfs hierarchy. To enable MSI support
on device "0000:00:0e", do:
5.3. Disabling MSIs on a single device
echo 1 > /sys/bus/pci/devices/0000:00:0e/msi_bus
Some devices are known to have faulty MSI implementations. Usually this
is handled in the individual device driver but occasionally it's necessary
to handle this with a quirk. Some drivers have an option to disable use
of MSI. While this is a convenient workaround for the driver author,
it is not good practise, and should not be emulated.
To disable MSI support, echo 0 instead of 1. Note that it should be
used with caution since changing this value might break interrupts.
5.4. Finding why MSIs are disabled on a device
6.3. Disabling MSI globally
From the above three sections, you can see that there are many reasons
why MSIs may not be enabled for a given device. Your first step should
be to examine your dmesg carefully to determine whether MSIs are enabled
for your machine. You should also check your .config to be sure you
have enabled CONFIG_PCI_MSI.
Some extreme cases may require to disable MSI globally on the system.
For now, the only known case is a Serverworks PCI-X chipsets (MSI are
not supported on several busses that are not all connected to the
chipset in the Linux PCI hierarchy). In the vast majority of other
cases, disabling only behind a specific bridge is enough.
Then, 'lspci -t' gives the list of bridges above a device. Reading
/sys/bus/pci/devices/*/msi_bus will tell you whether MSI are enabled (1)
or disabled (0). If 0 is found in any of the msi_bus files belonging
to bridges between the PCI root and the device, MSIs are disabled.
For debugging purpose, the user may also pass pci=nomsi on the kernel
command-line to explicitly disable MSI globally. But, once the appro-
priate quirks are added to the kernel, this option should not be
required anymore.
6.4. Finding why MSI cannot be enabled on a device
Assuming that MSI are not enabled on a device, you should look at
dmesg to find messages that quirks may output when disabling MSI
on some devices, some bridges or even globally.
Then, lspci -t gives the list of bridges above a device. Reading
/sys/bus/pci/devices/0000:00:0e/msi_bus will tell you whether MSI
are enabled (1) or disabled (0). In 0 is found in a single bridge
msi_bus file above the device, MSI cannot be enabled.
7. FAQ
Q1. Are there any limitations on using the MSI?
A1. If the PCI device supports MSI and conforms to the
specification and the platform supports the APIC local bus,
then using MSI should work.
Q2. Will it work on all the Pentium processors (P3, P4, Xeon,
AMD processors)? In P3 IPI's are transmitted on the APIC local
bus and in P4 and Xeon they are transmitted on the system
bus. Are there any implications with this?
A2. MSI support enables a PCI device sending an inbound
memory write (0xfeexxxxx as target address) on its PCI bus
directly to the FSB. Since the message address has a
redirection hint bit cleared, it should work.
Q3. The target address 0xfeexxxxx will be translated by the
Host Bridge into an interrupt message. Are there any
limitations on the chipsets such as Intel 8xx, Intel e7xxx,
or VIA?
A3. If these chipsets support an inbound memory write with
target address set as 0xfeexxxxx, as conformed to PCI
specification 2.3 or latest, then it should work.
Q4. From the driver point of view, if the MSI is lost because
of errors occurring during inbound memory write, then it may
wait forever. Is there a mechanism for it to recover?
A4. Since the target of the transaction is an inbound memory
write, all transaction termination conditions (Retry,
Master-Abort, Target-Abort, or normal completion) are
supported. A device sending an MSI must abide by all the PCI
rules and conditions regarding that inbound memory write. So,
if a retry is signaled it must retry, etc... We believe that
the recommendation for Abort is also a retry (refer to PCI
specification 2.3 or latest).
It is also worth checking the device driver to see whether it supports MSIs.
For example, it may contain calls to pci_enable_msi(), pci_enable_msix() or
pci_enable_msi_block().

99
Documentation/PCI/pci-iov-howto.txt Normal file
View file

@ -0,0 +1,99 @@
PCI Express I/O Virtualization Howto
Copyright (C) 2009 Intel Corporation
Yu Zhao <yu.zhao@intel.com>
1. Overview
1.1 What is SR-IOV
Single Root I/O Virtualization (SR-IOV) is a PCI Express Extended
capability which makes one physical device appear as multiple virtual
devices. The physical device is referred to as Physical Function (PF)
while the virtual devices are referred to as Virtual Functions (VF).
Allocation of the VF can be dynamically controlled by the PF via
registers encapsulated in the capability. By default, this feature is
not enabled and the PF behaves as traditional PCIe device. Once it's
turned on, each VF's PCI configuration space can be accessed by its own
Bus, Device and Function Number (Routing ID). And each VF also has PCI
Memory Space, which is used to map its register set. VF device driver
operates on the register set so it can be functional and appear as a
real existing PCI device.
2. User Guide
2.1 How can I enable SR-IOV capability
The device driver (PF driver) will control the enabling and disabling
of the capability via API provided by SR-IOV core. If the hardware
has SR-IOV capability, loading its PF driver would enable it and all
VFs associated with the PF.
2.2 How can I use the Virtual Functions
The VF is treated as hot-plugged PCI devices in the kernel, so they
should be able to work in the same way as real PCI devices. The VF
requires device driver that is same as a normal PCI device's.
3. Developer Guide
3.1 SR-IOV API
To enable SR-IOV capability:
int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
'nr_virtfn' is number of VFs to be enabled.
To disable SR-IOV capability:
void pci_disable_sriov(struct pci_dev *dev);
To notify SR-IOV core of Virtual Function Migration:
irqreturn_t pci_sriov_migration(struct pci_dev *dev);
3.2 Usage example
Following piece of code illustrates the usage of the SR-IOV API.
static int __devinit dev_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
pci_enable_sriov(dev, NR_VIRTFN);
...
return 0;
}
static void __devexit dev_remove(struct pci_dev *dev)
{
pci_disable_sriov(dev);
...
}
static int dev_suspend(struct pci_dev *dev, pm_message_t state)
{
...
return 0;
}
static int dev_resume(struct pci_dev *dev)
{
...
return 0;
}
static void dev_shutdown(struct pci_dev *dev)
{
...
}
static struct pci_driver dev_driver = {
.name = "SR-IOV Physical Function driver",
.id_table = dev_id_table,
.probe = dev_probe,
.remove = __devexit_p(dev_remove),
.suspend = dev_suspend,
.resume = dev_resume,
.shutdown = dev_shutdown,
};

6
Documentation/RCU/listRCU.txt
View file

@ -118,7 +118,7 @@ Following are the RCU equivalents for these two functions:
list_for_each_entry(e, list, list) {
if (!audit_compare_rule(rule, &e->rule)) {
list_del_rcu(&e->list);
call_rcu(&e->rcu, audit_free_rule, e);
call_rcu(&e->rcu, audit_free_rule);
return 0;
}
}
@ -206,7 +206,7 @@ RCU ("read-copy update") its name. The RCU code is as follows:
ne->rule.action = newaction;
ne->rule.file_count = newfield_count;
list_replace_rcu(e, ne);
call_rcu(&e->rcu, audit_free_rule, e);
call_rcu(&e->rcu, audit_free_rule);
return 0;
}
}
@ -283,7 +283,7 @@ flag under the spinlock as follows:
list_del_rcu(&e->list);
e->deleted = 1;
spin_unlock(&e->lock);
call_rcu(&e->rcu, audit_free_rule, e);
call_rcu(&e->rcu, audit_free_rule);
return 0;
}
}

2
Documentation/RCU/rcu.txt
View file

@ -81,7 +81,7 @@ o I hear that RCU needs work in order to support realtime kernels?
This work is largely completed. Realtime-friendly RCU can be
enabled via the CONFIG_PREEMPT_RCU kernel configuration parameter.
However, work is in progress for enabling priority boosting of
preempted RCU read-side critical sections.This is needed if you
preempted RCU read-side critical sections. This is needed if you
have CPU-bound realtime threads.
o Where can I find more information on RCU?

4
Documentation/RCU/rculist_nulls.txt
View file

@ -21,7 +21,7 @@ if (obj) {
/*
* Because a writer could delete object, and a writer could
* reuse these object before the RCU grace period, we
* must check key after geting the reference on object
* must check key after getting the reference on object
*/
if (obj->key != key) { // not the object we expected
put_ref(obj);
@ -117,7 +117,7 @@ a race (some writer did a delete and/or a move of an object
to another chain) checking the final 'nulls' value if
the lookup met the end of chain. If final 'nulls' value
is not the slot number, then we must restart the lookup at
the begining. If the object was moved to same chain,
the beginning. If the object was moved to the same chain,
then the reader doesnt care : It might eventually
scan the list again without harm.

2
Documentation/blockdev/00-INDEX
View file

@ -8,6 +8,8 @@ cpqarray.txt
- info on using Compaq's SMART2 Intelligent Disk Array Controllers.
floppy.txt
- notes and driver options for the floppy disk driver.
mflash.txt
- info on mGine m(g)flash driver for linux.
nbd.txt
- info on a TCP implementation of a network block device.
paride.txt

84
Documentation/blockdev/mflash.txt Normal file
View file

@ -0,0 +1,84 @@
This document describes m[g]flash support in linux.
Contents
1. Overview
2. Reserved area configuration
3. Example of mflash platform driver registration
1. Overview
Mflash and gflash are embedded flash drive. The only difference is mflash is
MCP(Multi Chip Package) device. These two device operate exactly same way.
So the rest mflash repersents mflash and gflash altogether.
Internally, mflash has nand flash and other hardware logics and supports
2 different operation (ATA, IO) modes. ATA mode doesn't need any new
driver and currently works well under standard IDE subsystem. Actually it's
one chip SSD. IO mode is ATA-like custom mode for the host that doesn't have
IDE interface.
Followings are brief descriptions about IO mode.
A. IO mode based on ATA protocol and uses some custom command. (read confirm,
write confirm)
B. IO mode uses SRAM bus interface.
C. IO mode supports 4kB boot area, so host can boot from mflash.
2. Reserved area configuration
If host boot from mflash, usually needs raw area for boot loader image. All of
the mflash's block device operation will be taken this value as start offset.
Note that boot loader's size of reserved area and kernel configuration value
must be same.
3. Example of mflash platform driver registration
Working mflash is very straight forward. Adding platform device stuff to board
configuration file is all. Here is some pseudo example.
static struct mg_drv_data mflash_drv_data = {
/* If you want to polling driver set to 1 */
.use_polling = 0,
/* device attribution */
.dev_attr = MG_BOOT_DEV
};
static struct resource mg_mflash_rsc[] = {
/* Base address of mflash */
[0] = {
.start = 0x08000000,
.end = 0x08000000 + SZ_64K - 1,
.flags = IORESOURCE_MEM
},
/* mflash interrupt pin */
[1] = {
.start = IRQ_GPIO(84),
.end = IRQ_GPIO(84),
.flags = IORESOURCE_IRQ
},
/* mflash reset pin */
[2] = {
.start = 43,
.end = 43,
.name = MG_RST_PIN,
.flags = IORESOURCE_IO
},
/* mflash reset-out pin
* If you use mflash as storage device (i.e. other than MG_BOOT_DEV),
* should assign this */
[3] = {
.start = 51,
.end = 51,
.name = MG_RSTOUT_PIN,
.flags = IORESOURCE_IO
}
};
static struct platform_device mflash_dev = {
.name = MG_DEV_NAME,
.id = -1,
.dev = {
.platform_data = &mflash_drv_data,
},
.num_resources = ARRAY_SIZE(mg_mflash_rsc),
.resource = mg_mflash_rsc
};
platform_device_register(&mflash_dev);

18
Documentation/cgroups/00-INDEX Normal file
View file

@ -0,0 +1,18 @@
00-INDEX
- this file
cgroups.txt
- Control Groups definition, implementation details, examples and API.
cpuacct.txt
- CPU Accounting Controller; account CPU usage for groups of tasks.
cpusets.txt
- documents the cpusets feature; assign CPUs and Mem to a set of tasks.
devices.txt
- Device Whitelist Controller; description, interface and security.
freezer-subsystem.txt
- checkpointing; rationale to not use signals, interface.
memcg_test.txt
- Memory Resource Controller; implementation details.
memory.txt
- Memory Resource Controller; design, accounting, interface, testing.
resource_counter.txt
- Resource Counter API.

36
Documentation/cgroups/cgroups.txt
View file

@ -56,7 +56,7 @@ hierarchy, and a set of subsystems; each subsystem has system-specific
state attached to each cgroup in the hierarchy. Each hierarchy has
an instance of the cgroup virtual filesystem associated with it.
At any one time there may be multiple active hierachies of task
At any one time there may be multiple active hierarchies of task
cgroups. Each hierarchy is a partition of all tasks in the system.
User level code may create and destroy cgroups by name in an
@ -124,10 +124,10 @@ following lines:
/ \
Prof (15%) students (5%)
Browsers like firefox/lynx go into the WWW network class, while (k)nfsd go
Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd go
into NFS network class.
At the same time firefox/lynx will share an appropriate CPU/Memory class
At the same time Firefox/Lynx will share an appropriate CPU/Memory class
depending on who launched it (prof/student).
With the ability to classify tasks differently for different resources
@ -325,7 +325,7 @@ and then start a subshell 'sh' in that cgroup:
Creating, modifying, using the cgroups can be done through the cgroup
virtual filesystem.
To mount a cgroup hierarchy will all available subsystems, type:
To mount a cgroup hierarchy with all available subsystems, type:
# mount -t cgroup xxx /dev/cgroup
The "xxx" is not interpreted by the cgroup code, but will appear in
@ -333,12 +333,23 @@ The "xxx" is not interpreted by the cgroup code, but will appear in
To mount a cgroup hierarchy with just the cpuset and numtasks
subsystems, type:
# mount -t cgroup -o cpuset,numtasks hier1 /dev/cgroup
# mount -t cgroup -o cpuset,memory hier1 /dev/cgroup
To change the set of subsystems bound to a mounted hierarchy, just
remount with different options:
# mount -o remount,cpuset,ns hier1 /dev/cgroup
# mount -o remount,cpuset,ns /dev/cgroup
Now memory is removed from the hierarchy and ns is added.
Note this will add ns to the hierarchy but won't remove memory or
cpuset, because the new options are appended to the old ones:
# mount -o remount,ns /dev/cgroup
To Specify a hierarchy's release_agent:
# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \
xxx /dev/cgroup
Note that specifying 'release_agent' more than once will return failure.
Note that changing the set of subsystems is currently only supported
when the hierarchy consists of a single (root) cgroup. Supporting
@ -349,6 +360,11 @@ Then under /dev/cgroup you can find a tree that corresponds to the
tree of the cgroups in the system. For instance, /dev/cgroup
is the cgroup that holds the whole system.
If you want to change the value of release_agent:
# echo "/sbin/new_release_agent" > /dev/cgroup/release_agent
It can also be changed via remount.
If you want to create a new cgroup under /dev/cgroup:
# cd /dev/cgroup
# mkdir my_cgroup
@ -476,11 +492,13 @@ cgroup->parent is still valid. (Note - can also be called for a
newly-created cgroup if an error occurs after this subsystem's
create() method has been called for the new cgroup).
void pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
int pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
Called before checking the reference count on each subsystem. This may
be useful for subsystems which have some extra references even if
there are not tasks in the cgroup.
there are not tasks in the cgroup. If pre_destroy() returns error code,
rmdir() will fail with it. From this behavior, pre_destroy() can be
called multiple times against a cgroup.
int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct task_struct *task)
@ -521,7 +539,7 @@ always handled well.
void post_clone(struct cgroup_subsys *ss, struct cgroup *cgrp)
(cgroup_mutex held by caller)
Called at the end of cgroup_clone() to do any paramater
Called at the end of cgroup_clone() to do any parameter
initialization which might be required before a task could attach. For
example in cpusets, no task may attach before 'cpus' and 'mems' are set
up.

18
Documentation/cgroups/cpuacct.txt
View file

@ -30,3 +30,21 @@ The above steps create a new group g1 and move the current shell
process (bash) into it. CPU time consumed by this bash and its children
can be obtained from g1/cpuacct.usage and the same is accumulated in
/cgroups/cpuacct.usage also.
cpuacct.stat file lists a few statistics which further divide the
CPU time obtained by the cgroup into user and system times. Currently
the following statistics are supported:
user: Time spent by tasks of the cgroup in user mode.
system: Time spent by tasks of the cgroup in kernel mode.
user and system are in USER_HZ unit.
cpuacct controller uses percpu_counter interface to collect user and
system times. This has two side effects:
- It is theoretically possible to see wrong values for user and system times.
This is because percpu_counter_read() on 32bit systems isn't safe
against concurrent writes.
- It is possible to see slightly outdated values for user and system times
due to the batch processing nature of percpu_counter.

12
Documentation/cgroups/cpusets.txt
View file

@ -131,7 +131,7 @@ Cpusets extends these two mechanisms as follows:
- The hierarchy of cpusets can be mounted at /dev/cpuset, for
browsing and manipulation from user space.
- A cpuset may be marked exclusive, which ensures that no other
cpuset (except direct ancestors and descendents) may contain
cpuset (except direct ancestors and descendants) may contain
any overlapping CPUs or Memory Nodes.
- You can list all the tasks (by pid) attached to any cpuset.
@ -226,7 +226,7 @@ nodes with memory--using the cpuset_track_online_nodes() hook.
--------------------------------
If a cpuset is cpu or mem exclusive, no other cpuset, other than
a direct ancestor or descendent, may share any of the same CPUs or
a direct ancestor or descendant, may share any of the same CPUs or
Memory Nodes.
A cpuset that is mem_exclusive *or* mem_hardwall is "hardwalled",
@ -427,7 +427,7 @@ child cpusets have this flag enabled.
When doing this, you don't usually want to leave any unpinned tasks in
the top cpuset that might use non-trivial amounts of CPU, as such tasks
may be artificially constrained to some subset of CPUs, depending on
the particulars of this flag setting in descendent cpusets. Even if
the particulars of this flag setting in descendant cpusets. Even if
such a task could use spare CPU cycles in some other CPUs, the kernel
scheduler might not consider the possibility of load balancing that
task to that underused CPU.
@ -531,9 +531,9 @@ be idle.
Of course it takes some searching cost to find movable tasks and/or
idle CPUs, the scheduler might not search all CPUs in the domain
everytime. In fact, in some architectures, the searching ranges on
every time. In fact, in some architectures, the searching ranges on
events are limited in the same socket or node where the CPU locates,
while the load balance on tick searchs all.
while the load balance on tick searches all.
For example, assume CPU Z is relatively far from CPU X. Even if CPU Z
is idle while CPU X and the siblings are busy, scheduler can't migrate
@ -601,7 +601,7 @@ its new cpuset, then the task will continue to use whatever subset
of MPOL_BIND nodes are still allowed in the new cpuset. If the task
was using MPOL_BIND and now none of its MPOL_BIND nodes are allowed
in the new cpuset, then the task will be essentially treated as if it
was MPOL_BIND bound to the new cpuset (even though its numa placement,
was MPOL_BIND bound to the new cpuset (even though its NUMA placement,
as queried by get_mempolicy(), doesn't change). If a task is moved
from one cpuset to another, then the kernel will adjust the tasks
memory placement, as above, the next time that the kernel attempts

2
Documentation/cgroups/devices.txt
View file

@ -42,7 +42,7 @@ suffice, but we can decide the best way to adequately restrict
movement as people get some experience with this. We may just want
to require CAP_SYS_ADMIN, which at least is a separate bit from
CAP_MKNOD. We may want to just refuse moving to a cgroup which
isn't a descendent of the current one. Or we may want to use
isn't a descendant of the current one. Or we may want to use
CAP_MAC_ADMIN, since we really are trying to lock down root.
CAP_SYS_ADMIN is needed to modify the whitelist or move another

22
Documentation/cgroups/memcg_test.txt
View file

@ -1,5 +1,5 @@
Memory Resource Controller(Memcg) Implementation Memo.
Last Updated: 2009/1/19
Last Updated: 2009/1/20
Base Kernel Version: based on 2.6.29-rc2.
Because VM is getting complex (one of reasons is memcg...), memcg's behavior
@ -356,7 +356,25 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
(Shell-B)
# move all tasks in /cgroup/test to /cgroup
# /sbin/swapoff -a
# rmdir /test/cgroup
# rmdir /cgroup/test
# kill malloc task.
Of course, tmpfs v.s. swapoff test should be tested, too.
9.8 OOM-Killer
Out-of-memory caused by memcg's limit will kill tasks under
the memcg. When hierarchy is used, a task under hierarchy
will be killed by the kernel.
In this case, panic_on_oom shouldn't be invoked and tasks
in other groups shouldn't be killed.
It's not difficult to cause OOM under memcg as following.
Case A) when you can swapoff
#swapoff -a
#echo 50M > /memory.limit_in_bytes
run 51M of malloc
Case B) when you use mem+swap limitation.
#echo 50M > memory.limit_in_bytes
#echo 50M > memory.memsw.limit_in_bytes
run 51M of malloc

51
Documentation/cgroups/memory.txt
View file

@ -6,15 +6,14 @@ used here with the memory controller that is used in hardware.
Salient features
a. Enable control of both RSS (mapped) and Page Cache (unmapped) pages
a. Enable control of Anonymous, Page Cache (mapped and unmapped) and
Swap Cache memory pages.
b. The infrastructure allows easy addition of other types of memory to control
c. Provides *zero overhead* for non memory controller users
d. Provides a double LRU: global memory pressure causes reclaim from the
global LRU; a cgroup on hitting a limit, reclaims from the per
cgroup LRU
NOTE: Swap Cache (unmapped) is not accounted now.
Benefits and Purpose of the memory controller
The memory controller isolates the memory behaviour of a group of tasks
@ -290,34 +289,44 @@ will be charged as a new owner of it.
moved to the parent. If you want to avoid that, force_empty will be useful.
5.2 stat file
memory.stat file includes following statistics (now)
cache - # of pages from page-cache and shmem.
rss - # of pages from anonymous memory.
pgpgin - # of event of charging
pgpgout - # of event of uncharging
active_anon - # of pages on active lru of anon, shmem.
inactive_anon - # of pages on active lru of anon, shmem
active_file - # of pages on active lru of file-cache
inactive_file - # of pages on inactive lru of file cache
unevictable - # of pages cannot be reclaimed.(mlocked etc)
Below is depend on CONFIG_DEBUG_VM.
inactive_ratio - VM inernal parameter. (see mm/page_alloc.c)
recent_rotated_anon - VM internal parameter. (see mm/vmscan.c)
recent_rotated_file - VM internal parameter. (see mm/vmscan.c)
recent_scanned_anon - VM internal parameter. (see mm/vmscan.c)
recent_scanned_file - VM internal parameter. (see mm/vmscan.c)
memory.stat file includes following statistics
Memo:
cache - # of bytes of page cache memory.
rss - # of bytes of anonymous and swap cache memory.
pgpgin - # of pages paged in (equivalent to # of charging events).
pgpgout - # of pages paged out (equivalent to # of uncharging events).
active_anon - # of bytes of anonymous and swap cache memory on active
lru list.
inactive_anon - # of bytes of anonymous memory and swap cache memory on
inactive lru list.
active_file - # of bytes of file-backed memory on active lru list.
inactive_file - # of bytes of file-backed memory on inactive lru list.
unevictable - # of bytes of memory that cannot be reclaimed (mlocked etc).
The following additional stats are dependent on CONFIG_DEBUG_VM.
inactive_ratio - VM internal parameter. (see mm/page_alloc.c)
recent_rotated_anon - VM internal parameter. (see mm/vmscan.c)
recent_rotated_file - VM internal parameter. (see mm/vmscan.c)
recent_scanned_anon - VM internal parameter. (see mm/vmscan.c)
recent_scanned_file - VM internal parameter. (see mm/vmscan.c)
Memo:
recent_rotated means recent frequency of lru rotation.
recent_scanned means recent # of scans to lru.
showing for better debug please see the code for meanings.
Note:
Only anonymous and swap cache memory is listed as part of 'rss' stat.
This should not be confused with the true 'resident set size' or the
amount of physical memory used by the cgroup. Per-cgroup rss
accounting is not done yet.
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
Following cgroup's swapiness can't be changed.
Following cgroups' swapiness can't be changed.
- root cgroup (uses /proc/sys/vm/swappiness).
- a cgroup which uses hierarchy and it has child cgroup.
- a cgroup which uses hierarchy and not the root of hierarchy.

27
Documentation/cgroups/resource_counter.txt
View file

@ -47,13 +47,18 @@ to work with it.
2. Basic accounting routines
a. void res_counter_init(struct res_counter *rc)
a. void res_counter_init(struct res_counter *rc,
struct res_counter *rc_parent)
Initializes the resource counter. As usual, should be the first
routine called for a new counter.
b. int res_counter_charge[_locked]
(struct res_counter *rc, unsigned long val)
The struct res_counter *parent can be used to define a hierarchical
child -> parent relationship directly in the res_counter structure,
NULL can be used to define no relationship.
c. int res_counter_charge(struct res_counter *rc, unsigned long val,
struct res_counter **limit_fail_at)
When a resource is about to be allocated it has to be accounted
with the appropriate resource counter (controller should determine
@ -67,15 +72,25 @@ to work with it.
* if the charging is performed first, then it should be uncharged
on error path (if the one is called).
c. void res_counter_uncharge[_locked]
If the charging fails and a hierarchical dependency exists, the
limit_fail_at parameter is set to the particular res_counter element
where the charging failed.
d. int res_counter_charge_locked
(struct res_counter *rc, unsigned long val)
The same as res_counter_charge(), but it must not acquire/release the
res_counter->lock internally (it must be called with res_counter->lock
held).
e. void res_counter_uncharge[_locked]
(struct res_counter *rc, unsigned long val)
When a resource is released (freed) it should be de-accounted
from the resource counter it was accounted to. This is called
"uncharging".
The _locked routines imply that the res_counter->lock is taken.
The _locked routines imply that the res_counter->lock is taken.
2.1 Other accounting routines

127
Documentation/devices.txt
View file

@ -1,9 +1,9 @@
LINUX ALLOCATED DEVICES (2.6+ version)
Maintained by Torben Mathiasen <device@lanana.org>
Maintained by Alan Cox <device@lanana.org>
Last revised: 29 November 2006
Last revised: 6th April 2009
This list is the Linux Device List, the official registry of allocated
device numbers and /dev directory nodes for the Linux operating
@ -67,6 +67,11 @@ up to date. Due to the number of registrations I have to maintain it
in "batch mode", so there is likely additional registrations that
haven't been listed yet.
Fourth, remember that Linux now has extensive support for dynamic allocation
of device numbering and can use sysfs and udev to handle the naming needs.
There are still some exceptions in the serial and boot device area. Before
asking for a device number make sure you actually need one.
Finally, sometimes I have to play "namespace police." Please don't be
offended. I often get submissions for /dev names that would be bound
to cause conflicts down the road. I am trying to avoid getting in a
@ -101,7 +106,7 @@ Your cooperation is appreciated.
0 = /dev/ram0 First RAM disk
1 = /dev/ram1 Second RAM disk
...
250 = /dev/initrd Initial RAM disk {2.6}
250 = /dev/initrd Initial RAM disk
Older kernels had /dev/ramdisk (1, 1) here.
/dev/initrd refers to a RAM disk which was preloaded
@ -340,7 +345,7 @@ Your cooperation is appreciated.
14 = /dev/touchscreen/ucb1x00 UCB 1x00 touchscreen
15 = /dev/touchscreen/mk712 MK712 touchscreen
128 = /dev/beep Fancy beep device
129 = /dev/modreq Kernel module load request {2.6}
129 =
130 = /dev/watchdog Watchdog timer port
131 = /dev/temperature Machine internal temperature
132 = /dev/hwtrap Hardware fault trap
@ -350,10 +355,10 @@ Your cooperation is appreciated.
139 = /dev/openprom SPARC OpenBoot PROM
140 = /dev/relay8 Berkshire Products Octal relay card
141 = /dev/relay16 Berkshire Products ISO-16 relay card
142 = /dev/msr x86 model-specific registers {2.6}
142 =
143 = /dev/pciconf PCI configuration space
144 = /dev/nvram Non-volatile configuration RAM
145 = /dev/hfmodem Soundcard shortwave modem control {2.6}
145 = /dev/hfmodem Soundcard shortwave modem control
146 = /dev/graphics Linux/SGI graphics device
147 = /dev/opengl Linux/SGI OpenGL pipe
148 = /dev/gfx Linux/SGI graphics effects device
@ -435,6 +440,9 @@ Your cooperation is appreciated.
228 = /dev/hpet HPET driver
229 = /dev/fuse Fuse (virtual filesystem in user-space)
230 = /dev/midishare MidiShare driver
231 = /dev/snapshot System memory snapshot device
232 = /dev/kvm Kernel-based virtual machine (hardware virtualization extensions)
233 = /dev/kmview View-OS A process with a view
240-254 Reserved for local use
255 Reserved for MISC_DYNAMIC_MINOR
@ -466,10 +474,7 @@ Your cooperation is appreciated.
The device names specified are proposed -- if there
are "standard" names for these devices, please let me know.
12 block MSCDEX CD-ROM callback support {2.6}
0 = /dev/dos_cd0 First MSCDEX CD-ROM
1 = /dev/dos_cd1 Second MSCDEX CD-ROM
...
12 block
13 char Input core
0 = /dev/input/js0 First joystick
@ -498,7 +503,7 @@ Your cooperation is appreciated.
2 = /dev/midi00 First MIDI port
3 = /dev/dsp Digital audio
4 = /dev/audio Sun-compatible digital audio
6 = /dev/sndstat Sound card status information {2.6}
6 =
7 = /dev/audioctl SPARC audio control device
8 = /dev/sequencer2 Sequencer -- alternate device
16 = /dev/mixer1 Second soundcard mixer control
@ -510,14 +515,7 @@ Your cooperation is appreciated.
34 = /dev/midi02 Third MIDI port
50 = /dev/midi03 Fourth MIDI port
14 block BIOS harddrive callback support {2.6}
0 = /dev/dos_hda First BIOS harddrive whole disk
64 = /dev/dos_hdb Second BIOS harddrive whole disk
128 = /dev/dos_hdc Third BIOS harddrive whole disk
192 = /dev/dos_hdd Fourth BIOS harddrive whole disk
Partitions are handled in the same way as IDE disks
(see major number 3).
14 block
15 char Joystick
0 = /dev/js0 First analog joystick
@ -535,14 +533,14 @@ Your cooperation is appreciated.
16 block GoldStar CD-ROM
0 = /dev/gscd GoldStar CD-ROM
17 char Chase serial card
17 char OBSOLETE (was Chase serial card)
0 = /dev/ttyH0 First Chase port
1 = /dev/ttyH1 Second Chase port
...
17 block Optics Storage CD-ROM
0 = /dev/optcd Optics Storage CD-ROM
18 char Chase serial card - alternate devices
18 char OBSOLETE (was Chase serial card - alternate devices)
0 = /dev/cuh0 Callout device for ttyH0
1 = /dev/cuh1 Callout device for ttyH1
...
@ -644,8 +642,7 @@ Your cooperation is appreciated.
2 = /dev/sbpcd2 Panasonic CD-ROM controller 0 unit 2
3 = /dev/sbpcd3 Panasonic CD-ROM controller 0 unit 3
26 char Quanta WinVision frame grabber {2.6}
0 = /dev/wvisfgrab Quanta WinVision frame grabber
26 char
26 block Second Matsushita (Panasonic/SoundBlaster) CD-ROM
0 = /dev/sbpcd4 Panasonic CD-ROM controller 1 unit 0
@ -872,7 +869,7 @@ Your cooperation is appreciated.
and "user level packet I/O." This board is also
accessible as a standard networking "eth" device.
38 block Reserved for Linux/AP+
38 block OBSOLETE (was Linux/AP+)
39 char ML-16P experimental I/O board
0 = /dev/ml16pa-a0 First card, first analog channel
@ -892,29 +889,16 @@ Your cooperation is appreciated.
50 = /dev/ml16pb-c1 Second card, second counter/timer
51 = /dev/ml16pb-c2 Second card, third counter/timer
...
39 block Reserved for Linux/AP+
39 block
40 char Matrox Meteor frame grabber {2.6}
0 = /dev/mmetfgrab Matrox Meteor frame grabber
40 char
40 block Syquest EZ135 parallel port removable drive
0 = /dev/eza Parallel EZ135 drive, whole disk
This device is obsolete and will be removed in a
future version of Linux. It has been replaced with
the parallel port IDE disk driver at major number 45.
Partitions are handled in the same way as IDE disks
(see major number 3).
40 block
41 char Yet Another Micro Monitor
0 = /dev/yamm Yet Another Micro Monitor
41 block MicroSolutions BackPack parallel port CD-ROM
0 = /dev/bpcd BackPack CD-ROM
This device is obsolete and will be removed in a
future version of Linux. It has been replaced with
the parallel port ATAPI CD-ROM driver at major number 46.
41 block
42 char Demo/sample use
@ -1681,13 +1665,7 @@ Your cooperation is appreciated.
disks (see major number 3) except that the limit on
partitions is 15.
93 char IBM Smart Capture Card frame grabber {2.6}
0 = /dev/iscc0 First Smart Capture Card
1 = /dev/iscc1 Second Smart Capture Card
...
128 = /dev/isccctl0 First Smart Capture Card control
129 = /dev/isccctl1 Second Smart Capture Card control
...
93 char
93 block NAND Flash Translation Layer filesystem
0 = /dev/nftla First NFTL layer
@ -1695,10 +1673,7 @@ Your cooperation is appreciated.
...
240 = /dev/nftlp 16th NTFL layer
94 char miroVIDEO DC10/30 capture/playback device {2.6}
0 = /dev/dcxx0 First capture card
1 = /dev/dcxx1 Second capture card
...
94 char
94 block IBM S/390 DASD block storage
0 = /dev/dasda First DASD device, major
@ -1791,11 +1766,7 @@ Your cooperation is appreciated.
...
15 = /dev/amiraid/ar?p15 15th partition
102 char Philips SAA5249 Teletext signal decoder {2.6}
0 = /dev/tlk0 First Teletext decoder
1 = /dev/tlk1 Second Teletext decoder
2 = /dev/tlk2 Third Teletext decoder
3 = /dev/tlk3 Fourth Teletext decoder
102 char
102 block Compressed block device
0 = /dev/cbd/a First compressed block device, whole device
@ -1916,10 +1887,7 @@ Your cooperation is appreciated.
DAC960 (see major number 48) except that the limit on
partitions is 15.
111 char Philips SAA7146-based audio/video card {2.6}
0 = /dev/av0 First A/V card
1 = /dev/av1 Second A/V card
...
111 char
111 block Compaq Next Generation Drive Array, eighth controller
0 = /dev/cciss/c7d0 First logical drive, whole disk
@ -2079,8 +2047,8 @@ Your cooperation is appreciated.
...
119 char VMware virtual network control
0 = /dev/vmnet0 1st virtual network
1 = /dev/vmnet1 2nd virtual network
0 = /dev/vnet0 1st virtual network
1 = /dev/vnet1 2nd virtual network
...
120-127 char LOCAL/EXPERIMENTAL USE
@ -2450,7 +2418,7 @@ Your cooperation is appreciated.
2 = /dev/raw/raw2 Second raw I/O device
...
163 char UNASSIGNED (was Radio Tech BIM-XXX-RS232 radio modem - see 51)
163 char
164 char Chase Research AT/PCI-Fast serial card
0 = /dev/ttyCH0 AT/PCI-Fast board 0, port 0
@ -2542,6 +2510,12 @@ Your cooperation is appreciated.
1 = /dev/clanvi1 Second cLAN adapter
...
179 block MMC block devices
0 = /dev/mmcblk0 First SD/MMC card
1 = /dev/mmcblk0p1 First partition on first MMC card
8 = /dev/mmcblk1 Second SD/MMC card
...
179 char CCube DVXChip-based PCI products
0 = /dev/dvxirq0 First DVX device
1 = /dev/dvxirq1 Second DVX device
@ -2560,6 +2534,9 @@ Your cooperation is appreciated.
96 = /dev/usb/hiddev0 1st USB HID device
...
111 = /dev/usb/hiddev15 16th USB HID device
112 = /dev/usb/auer0 1st auerswald ISDN device
...
127 = /dev/usb/auer15 16th auerswald ISDN device
128 = /dev/usb/brlvgr0 First Braille Voyager device
...
131 = /dev/usb/brlvgr3 Fourth Braille Voyager device
@ -2810,6 +2787,20 @@ Your cooperation is appreciated.
...
190 = /dev/ttyUL3 Xilinx uartlite - port 3
191 = /dev/xvc0 Xen virtual console - port 0
192 = /dev/ttyPZ0 pmac_zilog - port 0
...
195 = /dev/ttyPZ3 pmac_zilog - port 3
196 = /dev/ttyTX0 TX39/49 serial port 0
...
204 = /dev/ttyTX7 TX39/49 serial port 7
205 = /dev/ttySC0 SC26xx serial port 0
206 = /dev/ttySC1 SC26xx serial port 1
207 = /dev/ttySC2 SC26xx serial port 2
208 = /dev/ttySC3 SC26xx serial port 3
209 = /dev/ttyMAX0 MAX3100 serial port 0
210 = /dev/ttyMAX1 MAX3100 serial port 1
211 = /dev/ttyMAX2 MAX3100 serial port 2
212 = /dev/ttyMAX3 MAX3100 serial port 3
205 char Low-density serial ports (alternate device)
0 = /dev/culu0 Callout device for ttyLU0
@ -3145,6 +3136,14 @@ Your cooperation is appreciated.
1 = /dev/blockrom1 Second ROM card's translation layer interface
...
259 block Block Extended Major
Used dynamically to hold additional partition minor
numbers and allow large numbers of partitions per device
259 char FPGA configuration interfaces
0 = /dev/icap0 First Xilinx internal configuration
1 = /dev/icap1 Second Xilinx internal configuration
260 char OSD (Object-based-device) SCSI Device
0 = /dev/osd0 First OSD Device
1 = /dev/osd1 Second OSD Device

2
Documentation/fb/00-INDEX
View file

@ -11,8 +11,6 @@ aty128fb.txt
- info on the ATI Rage128 frame buffer driver.
cirrusfb.txt
- info on the driver for Cirrus Logic chipsets.
cyblafb/
- directory with documentation files related to the cyblafb driver.
deferred_io.txt
- an introduction to deferred IO.
fbcon.txt

13
Documentation/fb/cyblafb/bugs
View file

@ -1,13 +0,0 @@
Bugs
====
I currently don't know of any bug. Please do send reports to:
- linux-fbdev-devel@lists.sourceforge.net
- Knut_Petersen@t-online.de.
Untested features
=================
All LCD stuff is untested. If it worked in tridentfb, it should work in
cyblafb. Please test and report the results to Knut_Petersen@t-online.de.

7
Documentation/fb/cyblafb/credits
View file

@ -1,7 +0,0 @@
Thanks to
=========
* Alan Hourihane, for writing the X trident driver
* Jani Monoses, for writing the tridentfb driver
* Antonino A. Daplas, for review of the first published
version of cyblafb and some code
* Jochen Hein, for testing and a helpfull bug report

17
Documentation/fb/cyblafb/documentation
View file

@ -1,17 +0,0 @@
Available Documentation
=======================
Apollo PLE 133 Chipset VT8601A North Bridge Datasheet, Rev. 1.82, October 22,
2001, available from VIA:
http://www.viavpsd.com/product/6/15/DS8601A182.pdf
The datasheet is incomplete, some registers that need to be programmed are not
explained at all and important bits are listed as "reserved". But you really
need the datasheet to understand the code. "p. xxx" comments refer to page
numbers of this document.
XFree/XOrg drivers are available and of good quality, looking at the code
there is a good idea if the datasheet does not provide enough information
or if the datasheet seems to be wrong.

154
Documentation/fb/cyblafb/fb.modes
View file

@ -1,154 +0,0 @@
#
# Sample fb.modes file
#
# Provides an incomplete list of working modes for
# the cyberblade/i1 graphics core.
#
# The value 4294967256 is used instead of -40. Of course, -40 is not
# a really reasonable value, but chip design does not always follow
# logic. Believe me, it's ok, and it's the way the BIOS does it.
#
# fbset requires 4294967256 in fb.modes and -40 as an argument to
# the -t parameter. That's also not too reasonable, and it might change
# in the future or might even be differt for your current version.
#
mode "640x480-50"
geometry 640 480 2048 4096 8
timings 47619 4294967256 24 17 0 216 3
endmode
mode "640x480-60"
geometry 640 480 2048 4096 8
timings 39682 4294967256 24 17 0 216 3
endmode
mode "640x480-70"
geometry 640 480 2048 4096 8
timings 34013 4294967256 24 17 0 216 3
endmode
mode "640x480-72"
geometry 640 480 2048 4096 8
timings 33068 4294967256 24 17 0 216 3
endmode
mode "640x480-75"
geometry 640 480 2048 4096 8
timings 31746 4294967256 24 17 0 216 3
endmode
mode "640x480-80"
geometry 640 480 2048 4096 8
timings 29761 4294967256 24 17 0 216 3
endmode
mode "640x480-85"
geometry 640 480 2048 4096 8
timings 28011 4294967256 24 17 0 216 3
endmode
mode "800x600-50"
geometry 800 600 2048 4096 8
timings 30303 96 24 14 0 136 11
endmode
mode "800x600-60"
geometry 800 600 2048 4096 8
timings 25252 96 24 14 0 136 11
endmode
mode "800x600-70"
geometry 800 600 2048 4096 8
timings 21645 96 24 14 0 136 11
endmode
mode "800x600-72"
geometry 800 600 2048 4096 8
timings 21043 96 24 14 0 136 11
endmode
mode "800x600-75"
geometry 800 600 2048 4096 8
timings 20202 96 24 14 0 136 11
endmode
mode "800x600-80"
geometry 800 600 2048 4096 8
timings 18939 96 24 14 0 136 11
endmode
mode "800x600-85"
geometry 800 600 2048 4096 8
timings 17825 96 24 14 0 136 11
endmode
mode "1024x768-50"
geometry 1024 768 2048 4096 8
timings 19054 144 24 29 0 120 3
endmode
mode "1024x768-60"
geometry 1024 768 2048 4096 8
timings 15880 144 24 29 0 120 3
endmode
mode "1024x768-70"
geometry 1024 768 2048 4096 8
timings 13610 144 24 29 0 120 3
endmode
mode "1024x768-72"
geometry 1024 768 2048 4096 8
timings 13232 144 24 29 0 120 3
endmode
mode "1024x768-75"
geometry 1024 768 2048 4096 8
timings 12703 144 24 29 0 120 3
endmode
mode "1024x768-80"
geometry 1024 768 2048 4096 8
timings 11910 144 24 29 0 120 3
endmode
mode "1024x768-85"
geometry 1024 768 2048 4096 8
timings 11209 144 24 29 0 120 3
endmode
mode "1280x1024-50"
geometry 1280 1024 2048 4096 8
timings 11114 232 16 39 0 160 3
endmode
mode "1280x1024-60"
geometry 1280 1024 2048 4096 8
timings 9262 232 16 39 0 160 3
endmode
mode "1280x1024-70"
geometry 1280 1024 2048 4096 8
timings 7939 232 16 39 0 160 3
endmode
mode "1280x1024-72"
geometry 1280 1024 2048 4096 8
timings 7719 232 16 39 0 160 3
endmode
mode "1280x1024-75"
geometry 1280 1024 2048 4096 8
timings 7410 232 16 39 0 160 3
endmode
mode "1280x1024-80"
geometry 1280 1024 2048 4096 8
timings 6946 232 16 39 0 160 3
endmode
mode "1280x1024-85"
geometry 1280 1024 2048 4096 8
timings 6538 232 16 39 0 160 3
endmode

79
Documentation/fb/cyblafb/performance
View file

@ -1,79 +0,0 @@
Speed
=====
CyBlaFB is much faster than tridentfb and vesafb. Compare the performance data
for mode 1280x1024-[8,16,32]@61 Hz.
Test 1: Cat a file with 2000 lines of 0 characters.
Test 2: Cat a file with 2000 lines of 80 characters.
Test 3: Cat a file with 2000 lines of 160 characters.
All values show system time use in seconds, kernel 2.6.12 was used for
the measurements. 2.6.13 is a bit slower, 2.6.14 hopefully will include a
patch that speeds up kernel bitblitting a lot ( > 20%).
+-----------+-----------------------------------------------------+
| | not accelerated |
| TRIDENTFB +-----------------+-----------------+-----------------+
| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
| | noypan | ypan | noypan | ypan | noypan | ypan |
+-----------+--------+--------+--------+--------+--------+--------+
| Test 1 | 4.31 | 4.33 | 6.05 | 12.81 | ---- | ---- |
| Test 2 | 67.94 | 5.44 | 123.16 | 14.79 | ---- | ---- |
| Test 3 | 131.36 | 6.55 | 240.12 | 16.76 | ---- | ---- |
+-----------+--------+--------+--------+--------+--------+--------+
| Comments | | | completely bro- |
| | | | ken, monitor |
| | | | switches off |
+-----------+-----------------+-----------------+-----------------+
+-----------+-----------------------------------------------------+
| | accelerated |
| TRIDENTFB +-----------------+-----------------+-----------------+
| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
| | noypan | ypan | noypan | ypan | noypan | ypan |
+-----------+--------+--------+--------+--------+--------+--------+
| Test 1 | ---- | ---- | 20.62 | 1.22 | ---- | ---- |
| Test 2 | ---- | ---- | 22.61 | 3.19 | ---- | ---- |
| Test 3 | ---- | ---- | 24.59 | 5.16 | ---- | ---- |
+-----------+--------+--------+--------+--------+--------+--------+
| Comments | broken, writing | broken, ok only | completely bro- |
| | to wrong places | if bgcolor is | ken, monitor |
| | on screen + bug | black, bug in | switches off |
| | in fillrect() | fillrect() | |
+-----------+-----------------+-----------------+-----------------+
+-----------+-----------------------------------------------------+
| | not accelerated |
| VESAFB +-----------------+-----------------+-----------------+
| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
| | noypan | ypan | noypan | ypan | noypan | ypan |
+-----------+--------+--------+--------+--------+--------+--------+
| Test 1 | 4.26 | 3.76 | 5.99 | 7.23 | ---- | ---- |
| Test 2 | 65.65 | 4.89 | 120.88 | 9.08 | ---- | ---- |
| Test 3 | 126.91 | 5.94 | 235.77 | 11.03 | ---- | ---- |
+-----------+--------+--------+--------+--------+--------+--------+
| Comments | vga=0x307 | vga=0x31a | vga=0x31b not |
| | fh=80kHz | fh=80kHz | supported by |
| | fv=75kHz | fv=75kHz | video BIOS and |
| | | | hardware |
+-----------+-----------------+-----------------+-----------------+
+-----------+-----------------------------------------------------+
| | accelerated |
| CYBLAFB +-----------------+-----------------+-----------------+
| | 8 bpp | 16 bpp | 32 bpp |
| | noypan | ypan | noypan | ypan | noypan | ypan |
+-----------+--------+--------+--------+--------+--------+--------+
| Test 1 | 8.02 | 0.23 | 19.04 | 0.61 | 57.12 | 2.74 |
| Test 2 | 8.38 | 0.55 | 19.39 | 0.92 | 57.54 | 3.13 |
| Test 3 | 8.73 | 0.86 | 19.74 | 1.24 | 57.95 | 3.51 |
+-----------+--------+--------+--------+--------+--------+--------+
| Comments | | | |
| | | | |
| | | | |
| | | | |
+-----------+-----------------+-----------------+-----------------+

31
Documentation/fb/cyblafb/todo
View file

@ -1,31 +0,0 @@
TODO / Missing features
=======================
Verify LCD stuff "stretch" and "center" options are
completely untested ... this code needs to be
verified. As I don't have access to such
hardware, please contact me if you are
willing run some tests.
Interlaced video modes The reason that interleaved
modes are disabled is that I do not know
the meaning of the vertical interlace
parameter. Also the datasheet mentions a
bit d8 of a horizontal interlace parameter,
but nowhere the lower 8 bits. Please help
if you can.
low-res double scan modes Who needs it?
accelerated color blitting Who needs it? The console driver does use color
blitting for nothing but drawing the penguine,
everything else is done using color expanding
blitting of 1bpp character bitmaps.
ioctls Who needs it?
TV-out Will be done later. Use "vga= " at boot time
to set a suitable video mode.
??? Feel free to contact me if you have any
feature requests

217
Documentation/fb/cyblafb/usage
View file

@ -1,217 +0,0 @@
CyBlaFB is a framebuffer driver for the Cyberblade/i1 graphics core integrated
into the VIA Apollo PLE133 (aka vt8601) south bridge. It is developed and
tested using a VIA EPIA 5000 board.
Cyblafb - compiled into the kernel or as a module?
==================================================
You might compile cyblafb either as a module or compile it permanently into the
kernel.
Unless you have a real reason to do so you should not compile both vesafb and
cyblafb permanently into the kernel. It's possible and it helps during the
developement cycle, but it's useless and will at least block some otherwise
usefull memory for ordinary users.
Selecting Modes
===============
Startup Mode
============
First of all, you might use the "vga=???" boot parameter as it is
documented in vesafb.txt and svga.txt. Cyblafb will detect the video
mode selected and will use the geometry and timings found by
inspecting the hardware registers.
video=cyblafb vga=0x317
Alternatively you might use a combination of the mode, ref and bpp
parameters. If you compiled the driver into the kernel, add something
like this to the kernel command line:
video=cyblafb:1280x1024,bpp=16,ref=50 ...
If you compiled the driver as a module, the same mode would be
selected by the following command:
modprobe cyblafb mode=1280x1024 bpp=16 ref=50 ...
None of the modes possible to select as startup modes are affected by
the problems described at the end of the next subsection.
For all startup modes cyblafb chooses a virtual x resolution of 2048,
the only exception is mode 1280x1024 in combination with 32 bpp. This
allows ywrap scrolling for all those modes if rotation is 0 or 2, and
also fast scrolling if rotation is 1 or 3. The default virtual y reso-
lution is 4096 for bpp == 8, 2048 for bpp==16 and 1024 for bpp == 32,
again with the only exception of 1280x1024 at 32 bpp.
Please do set your video memory size to 8 Mb in the Bios setup. Other
values will work, but performace is decreased for a lot of modes.
Mode changes using fbset
========================
You might use fbset to change the video mode, see "man fbset". Cyblafb
generally does assume that you know what you are doing. But it does
some checks, especially those that are needed to prevent you from
damaging your hardware.
- only 8, 16, 24 and 32 bpp video modes are accepted
- interlaced video modes are not accepted
- double scan video modes are not accepted
- if a flat panel is found, cyblafb does not allow you
to program a resolution higher than the physical
resolution of the flat panel monitor
- cyblafb does not allow vclk to exceed 230 MHz. As 32 bpp
and (currently) 24 bit modes use a doubled vclk internally,
the dotclock limit as seen by fbset is 115 MHz for those
modes and 230 MHz for 8 and 16 bpp modes.
- cyblafb will allow you to select very high resolutions as
long as the hardware can be programmed to these modes. The
documented limit 1600x1200 is not enforced, but don't expect
perfect signal quality.
Any request that violates the rules given above will be either changed
to something the hardware supports or an error value will be returned.
If you program a virtual y resolution higher than the hardware limit,
cyblafb will silently decrease that value to the highest possible
value. The same is true for a virtual x resolution that is not
supported by the hardware. Cyblafb tries to adapt vyres first because
vxres decides if ywrap scrolling is possible or not.
Attempts to disable acceleration are ignored, I believe that this is
safe.
Some video modes that should work do not work as expected. If you use
the standard fb.modes, fbset 640x480-60 will program that mode, but
you will see a vertical area, about two characters wide, with only
much darker characters than the other characters on the screen.
Cyblafb does allow that mode to be set, as it does not violate the
official specifications. It would need a lot of code to reliably sort
out all invalid modes, playing around with the margin values will
give a valid mode quickly. And if cyblafb would detect such an invalid
mode, should it silently alter the requested values or should it
report an error? Both options have some pros and cons. As stated
above, none of the startup modes are affected, and if you set
verbosity to 1 or higher, cyblafb will print the fbset command that
would be needed to program that mode using fbset.
Other Parameters
================
crt don't autodetect, assume monitor connected to
standard VGA connector
fp don't autodetect, assume flat panel display
connected to flat panel monitor interface
nativex inform driver about native x resolution of
flat panel monitor connected to special
interface (should be autodetected)
stretch stretch image to adapt low resolution modes to
higer resolutions of flat panel monitors
connected to special interface
center center image to adapt low resolution modes to
higer resolutions of flat panel monitors
connected to special interface
memsize use if autodetected memsize is wrong ...
should never be necessary
nopcirr disable PCI read retry
nopciwr disable PCI write retry
nopcirb disable PCI read bursts
nopciwb disable PCI write bursts
bpp bpp for specified modes
valid values: 8 || 16 || 24 || 32
ref refresh rate for specified mode
valid values: 50 <= ref <= 85
mode 640x480 or 800x600 or 1024x768 or 1280x1024
if not specified, the startup mode will be detected
and used, so you might also use the vga=??? parameter
described in vesafb.txt. If you do not specify a mode,
bpp and ref parameters are ignored.
verbosity 0 is the default, increase to at least 2 for every
bug report!
Development hints
=================
It's much faster do compile a module and to load the new version after
unloading the old module than to compile a new kernel and to reboot. So if you
try to work on cyblafb, it might be a good idea to use cyblafb as a module.
In real life, fast often means dangerous, and that's also the case here. If
you introduce a serious bug when cyblafb is compiled into the kernel, the
kernel will lock or oops with a high probability before the file system is
mounted, and the danger for your data is low. If you load a broken own version
of cyblafb on a running system, the danger for the integrity of the file
system is much higher as you might need a hard reset afterwards. Decide
yourself.
Module unloading, the vfb method
================================
If you want to unload/reload cyblafb using the virtual framebuffer, you need
to enable vfb support in the kernel first. After that, load the modules as
shown below:
modprobe vfb vfb_enable=1
modprobe fbcon
modprobe cyblafb
fbset -fb /dev/fb1 1280x1024-60 -vyres 2662
con2fb /dev/fb1 /dev/tty1
...
If you now made some changes to cyblafb and want to reload it, you might do it
as show below:
con2fb /dev/fb0 /dev/tty1
...
rmmod cyblafb
modprobe cyblafb
con2fb /dev/fb1 /dev/tty1
...
Of course, you might choose another mode, and most certainly you also want to
map some other /dev/tty* to the real framebuffer device. You might also choose
to compile fbcon as a kernel module or place it permanently in the kernel.
I do not know of any way to unload fbcon, and fbcon will prevent the
framebuffer device loaded first from unloading. [If there is a way, then
please add a description here!]
Module unloading, the vesafb method
===================================
Configure the kernel:
<*> Support for frame buffer devices
[*] VESA VGA graphics support
<M> Cyberblade/i1 support
Add e.g. "video=vesafb:ypan vga=0x307" to the kernel parameters. The ypan
parameter is important, choose any vga parameter you like as long as it is
a graphics mode.
After booting, load cyblafb without any mode and bpp parameter and assign
cyblafb to individual ttys using con2fb, e.g.:
modprobe cyblafb
con2fb /dev/fb1 /dev/tty1
Unloading cyblafb works without problems after you assign vesafb to all
ttys again, e.g.:
con2fb /dev/fb0 /dev/tty1
rmmod cyblafb

29
Documentation/fb/cyblafb/whatsnew
View file

@ -1,29 +0,0 @@
0.62
====
- the vesafb parameter has been removed as I decided to allow the
feature without any special parameter.
- Cyblafb does not use the vga style of panning any longer, now the
"right view" register in the graphics engine IO space is used. Without
that change it was impossible to use all available memory, and without
access to all available memory it is impossible to ywrap.
- The imageblit function now uses hardware acceleration for all font
widths. Hardware blitting across pixel column 2048 is broken in the
cyberblade/i1 graphics core, but we work around that hardware bug.
- modes with vxres != xres are supported now.
- ywrap scrolling is supported now and the default. This is a big
performance gain.
- default video modes use vyres > yres and vxres > xres to allow
almost optimal scrolling speed for normal and rotated screens
- some features mainly usefull for debugging the upper layers of the
framebuffer system have been added, have a look at the code
- fixed: Oops after unloading cyblafb when reading /proc/io*
- we work around some bugs of the higher framebuffer layers.

85
Documentation/fb/cyblafb/whycyblafb
View file

@ -1,85 +0,0 @@
I tried the following framebuffer drivers:
- TRIDENTFB is full of bugs. Acceleration is broken for Blade3D
graphics cores like the cyberblade/i1. It claims to support a great
number of devices, but documentation for most of these devices is
unfortunately not available. There is _no_ reason to use tridentfb
for cyberblade/i1 + CRT users. VESAFB is faster, and the one
advantage, mode switching, is broken in tridentfb.
- VESAFB is used by many distributions as a standard. Vesafb does
not support mode switching. VESAFB is a bit faster than the working
configurations of TRIDENTFB, but it is still too slow, even if you
use ypan.
- EPIAFB (you'll find it on sourceforge) supports the Cyberblade/i1
graphics core, but it still has serious bugs and developement seems
to have stopped. This is the one driver with TV-out support. If you
do need this feature, try epiafb.
None of these drivers was a real option for me.
I believe that is unreasonable to change code that announces to support 20
devices if I only have more or less sufficient documentation for exactly one
of these. The risk of breaking device foo while fixing device bar is too high.
So I decided to start CyBlaFB as a stripped down tridentfb.
All code specific to other Trident chips has been removed. After that there
were a lot of cosmetic changes to increase the readability of the code. All
register names were changed to those mnemonics used in the datasheet. Function
and macro names were changed if they hindered easy understanding of the code.
After that I debugged the code and implemented some new features. I'll try to
give a little summary of the main changes:
- calculation of vertical and horizontal timings was fixed
- video signal quality has been improved dramatically
- acceleration:
- fillrect and copyarea were fixed and reenabled
- color expanding imageblit was newly implemented, color
imageblit (only used to draw the penguine) still uses the
generic code.
- init of the acceleration engine was improved and moved to a
place where it really works ...
- sync function has a timeout now and tries to reset and
reinit the accel engine if necessary
- fewer slow copyarea calls when doing ypan scrolling by using
undocumented bit d21 of screen start address stored in
CR2B[5]. BIOS does use it also, so this should be safe.
- cyblafb rejects any attempt to set modes that would cause vclk
values above reasonable 230 MHz. 32bit modes use a clock
multiplicator of 2, so fbset does show the correct values for
pixclock but not for vclk in this case. The fbset limit is 115 MHz
for 32 bpp modes.
- cyblafb rejects modes known to be broken or unimplemented (all
interlaced modes, all doublescan modes for now)
- cyblafb now works independant of the video mode in effect at startup
time (tridentfb does not init all needed registers to reasonable
values)
- switching between video modes does work reliably now
- the first video mode now is the one selected on startup using the
vga=???? mechanism or any of
- 640x480, 800x600, 1024x768, 1280x1024
- 8, 16, 24 or 32 bpp
- refresh between 50 Hz and 85 Hz, 1 Hz steps (1280x1024-32
is limited to 63Hz)
- pci retry and pci burst mode are settable (try to disable if you
experience latency problems)
- built as a module cyblafb might be unloaded and reloaded using
the vfb module and con2vt or might be used together with vesafb

7
Documentation/fb/uvesafb.txt
View file

@ -59,7 +59,8 @@ Accepted options:
ypan Enable display panning using the VESA protected mode
interface. The visible screen is just a window of the
video memory, console scrolling is done by changing the
start of the window. Available on x86 only.
start of the window. This option is available on x86
only and is the default option on that architecture.
ywrap Same as ypan, but assumes your gfx board can wrap-around
the video memory (i.e. starts reading from top if it
@ -67,7 +68,7 @@ ywrap Same as ypan, but assumes your gfx board can wrap-around
Available on x86 only.
redraw Scroll by redrawing the affected part of the screen, this
is the safe (and slow) default.
is the default on non-x86.
(If you're using uvesafb as a module, the above three options are
used a parameter of the scroll option, e.g. scroll=ypan.)
@ -182,7 +183,7 @@ from the Video BIOS if you set pixclock to 0 in fb_var_screeninfo.
--
Michal Januszewski <spock@gentoo.org>
Last updated: 2007-06-16
Last updated: 2009-03-30
Documentation of the uvesafb options is loosely based on vesafb.txt.

73
Documentation/feature-removal-schedule.txt
View file

@ -255,6 +255,16 @@ Who: Jan Engelhardt <jengelh@computergmbh.de>
---------------------------
What: GPIO autorequest on gpio_direction_{input,output}() in gpiolib
When: February 2010
Why: All callers should use explicit gpio_request()/gpio_free().
The autorequest mechanism in gpiolib was provided mostly as a
migration aid for legacy GPIO interfaces (for SOC based GPIOs).
Those users have now largely migrated. Platforms implementing
the GPIO interfaces without using gpiolib will see no changes.
Who: David Brownell <dbrownell@users.sourceforge.net>
---------------------------
What: b43 support for firmware revision < 410
When: The schedule was July 2008, but it was decided that we are going to keep the
code as long as there are no major maintanance headaches.
@ -273,13 +283,6 @@ Who: Glauber Costa <gcosta@redhat.com>
---------------------------
What: remove HID compat support
When: 2.6.29
Why: needed only as a temporary solution until distros fix themselves up
Who: Jiri Slaby <jirislaby@gmail.com>
---------------------------
What: print_fn_descriptor_symbol()
When: October 2009
Why: The %pF vsprintf format provides the same functionality in a
@ -311,6 +314,18 @@ Who: Vlad Yasevich <vladislav.yasevich@hp.com>
---------------------------
What: Ability for non root users to shm_get hugetlb pages based on mlock
resource limits
When: 2.6.31
Why: Non root users need to be part of /proc/sys/vm/hugetlb_shm_group or
have CAP_IPC_LOCK to be able to allocate shm segments backed by
huge pages. The mlock based rlimit check to allow shm hugetlb is
inconsistent with mmap based allocations. Hence it is being
deprecated.
Who: Ravikiran Thirumalai <kiran@scalex86.org>
---------------------------
What: CONFIG_THERMAL_HWMON
When: January 2009
Why: This option was introduced just to allow older lm-sensors userspace
@ -339,7 +354,8 @@ Who: Krzysztof Piotr Oledzki <ole@ans.pl>
---------------------------
What: i2c_attach_client(), i2c_detach_client(), i2c_driver->detach_client()
What: i2c_attach_client(), i2c_detach_client(), i2c_driver->detach_client(),
i2c_adapter->client_register(), i2c_adapter->client_unregister
When: 2.6.30
Check: i2c_attach_client i2c_detach_client
Why: Deprecated by the new (standard) device driver binding model. Use
@ -380,3 +396,44 @@ Why: The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t)
have been kept around for migration reasons. After more than two years
it's time to remove them finally
Who: Thomas Gleixner <tglx@linutronix.de>
---------------------------
What: fakephp and associated sysfs files in /sys/bus/pci/slots/
When: 2011
Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to
represent a machine's physical PCI slots. The change in semantics
had userspace implications, as the hotplug core no longer allowed
drivers to create multiple sysfs files per physical slot (required
for multi-function devices, e.g.). fakephp was seen as a developer's
tool only, and its interface changed. Too late, we learned that
there were some users of the fakephp interface.
In 2.6.30, the original fakephp interface was restored. At the same
time, the PCI core gained the ability that fakephp provided, namely
function-level hot-remove and hot-add.
Since the PCI core now provides the same functionality, exposed in:
/sys/bus/pci/rescan
/sys/bus/pci/devices/.../remove
/sys/bus/pci/devices/.../rescan
there is no functional reason to maintain fakephp as well.
We will keep the existing module so that 'modprobe fakephp' will
present the old /sys/bus/pci/slots/... interface for compatibility,
but users are urged to migrate their applications to the API above.
After a reasonable transition period, we will remove the legacy
fakephp interface.
Who: Alex Chiang <achiang@hp.com>
---------------------------
What: i2c-voodoo3 driver
When: October 2009
Why: Superseded by tdfxfb. I2C/DDC support used to live in a separate
driver but this caused driver conflicts.
Who: Jean Delvare <khali@linux-fr.org>
Krzysztof Helt <krzysztof.h1@wp.pl>

2
Documentation/filesystems/00-INDEX
View file

@ -68,6 +68,8 @@ ncpfs.txt
- info on Novell Netware(tm) filesystem using NCP protocol.
nfsroot.txt
- short guide on setting up a diskless box with NFS root filesystem.
nilfs2.txt
- info and mount options for the NILFS2 filesystem.
ntfs.txt
- info and mount options for the NTFS filesystem (Windows NT).
ocfs2.txt

2
Documentation/filesystems/Locking
View file

@ -505,7 +505,7 @@ prototypes:
void (*open)(struct vm_area_struct*);
void (*close)(struct vm_area_struct*);
int (*fault)(struct vm_area_struct*, struct vm_fault *);
int (*page_mkwrite)(struct vm_area_struct *, struct page *);
int (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *);
int (*access)(struct vm_area_struct *, unsigned long, void*, int, int);
locking rules:

658
Documentation/filesystems/caching/backend-api.txt Normal file
View file

@ -0,0 +1,658 @@
==========================
FS-CACHE CACHE BACKEND API
==========================
The FS-Cache system provides an API by which actual caches can be supplied to
FS-Cache for it to then serve out to network filesystems and other interested
parties.
This API is declared in <linux/fscache-cache.h>.
====================================
INITIALISING AND REGISTERING A CACHE
====================================
To start off, a cache definition must be initialised and registered for each
cache the backend wants to make available. For instance, CacheFS does this in
the fill_super() operation on mounting.
The cache definition (struct fscache_cache) should be initialised by calling:
void fscache_init_cache(struct fscache_cache *cache,
struct fscache_cache_ops *ops,
const char *idfmt,
...);
Where:
(*) "cache" is a pointer to the cache definition;
(*) "ops" is a pointer to the table of operations that the backend supports on
this cache; and
(*) "idfmt" is a format and printf-style arguments for constructing a label
for the cache.
The cache should then be registered with FS-Cache by passing a pointer to the
previously initialised cache definition to:
int fscache_add_cache(struct fscache_cache *cache,
struct fscache_object *fsdef,
const char *tagname);
Two extra arguments should also be supplied:
(*) "fsdef" which should point to the object representation for the FS-Cache
master index in this cache. Netfs primary index entries will be created
here. FS-Cache keeps the caller's reference to the index object if
successful and will release it upon withdrawal of the cache.
(*) "tagname" which, if given, should be a text string naming this cache. If
this is NULL, the identifier will be used instead. For CacheFS, the
identifier is set to name the underlying block device and the tag can be
supplied by mount.
This function may return -ENOMEM if it ran out of memory or -EEXIST if the tag
is already in use. 0 will be returned on success.
=====================
UNREGISTERING A CACHE
=====================
A cache can be withdrawn from the system by calling this function with a
pointer to the cache definition:
void fscache_withdraw_cache(struct fscache_cache *cache);
In CacheFS's case, this is called by put_super().
========
SECURITY
========
The cache methods are executed one of two contexts:
(1) that of the userspace process that issued the netfs operation that caused
the cache method to be invoked, or
(2) that of one of the processes in the FS-Cache thread pool.
In either case, this may not be an appropriate context in which to access the
cache.
The calling process's fsuid, fsgid and SELinux security identities may need to
be masqueraded for the duration of the cache driver's access to the cache.
This is left to the cache to handle; FS-Cache makes no effort in this regard.
===================================
CONTROL AND STATISTICS PRESENTATION
===================================
The cache may present data to the outside world through FS-Cache's interfaces
in sysfs and procfs - the former for control and the latter for statistics.
A sysfs directory called /sys/fs/fscache/<cachetag>/ is created if CONFIG_SYSFS
is enabled. This is accessible through the kobject struct fscache_cache::kobj
and is for use by the cache as it sees fit.
========================
RELEVANT DATA STRUCTURES
========================
(*) Index/Data file FS-Cache representation cookie:
struct fscache_cookie {
struct fscache_object_def *def;
struct fscache_netfs *netfs;
void *netfs_data;
...
};
The fields that might be of use to the backend describe the object
definition, the netfs definition and the netfs's data for this cookie.
The object definition contain functions supplied by the netfs for loading
and matching index entries; these are required to provide some of the
cache operations.
(*) In-cache object representation:
struct fscache_object {
int debug_id;
enum {
FSCACHE_OBJECT_RECYCLING,
...
} state;
spinlock_t lock
struct fscache_cache *cache;
struct fscache_cookie *cookie;
...
};
Structures of this type should be allocated by the cache backend and
passed to FS-Cache when requested by the appropriate cache operation. In
the case of CacheFS, they're embedded in CacheFS's internal object
structures.
The debug_id is a simple integer that can be used in debugging messages
that refer to a particular object. In such a case it should be printed
using "OBJ%x" to be consistent with FS-Cache.
Each object contains a pointer to the cookie that represents the object it
is backing. An object should retired when put_object() is called if it is
in state FSCACHE_OBJECT_RECYCLING. The fscache_object struct should be
initialised by calling fscache_object_init(object).
(*) FS-Cache operation record:
struct fscache_operation {
atomic_t usage;
struct fscache_object *object;
unsigned long flags;
#define FSCACHE_OP_EXCLUSIVE
void (*processor)(struct fscache_operation *op);
void (*release)(struct fscache_operation *op);
...
};
FS-Cache has a pool of threads that it uses to give CPU time to the
various asynchronous operations that need to be done as part of driving
the cache. These are represented by the above structure. The processor
method is called to give the op CPU time, and the release method to get
rid of it when its usage count reaches 0.
An operation can be made exclusive upon an object by setting the
appropriate flag before enqueuing it with fscache_enqueue_operation(). If
an operation needs more processing time, it should be enqueued again.
(*) FS-Cache retrieval operation record:
struct fscache_retrieval {
struct fscache_operation op;
struct address_space *mapping;
struct list_head *to_do;
...
};
A structure of this type is allocated by FS-Cache to record retrieval and
allocation requests made by the netfs. This struct is then passed to the
backend to do the operation. The backend may get extra refs to it by
calling fscache_get_retrieval() and refs may be discarded by calling
fscache_put_retrieval().
A retrieval operation can be used by the backend to do retrieval work. To
do this, the retrieval->op.processor method pointer should be set
appropriately by the backend and fscache_enqueue_retrieval() called to
submit it to the thread pool. CacheFiles, for example, uses this to queue
page examination when it detects PG_lock being cleared.
The to_do field is an empty list available for the cache backend to use as
it sees fit.
(*) FS-Cache storage operation record:
struct fscache_storage {
struct fscache_operation op;
pgoff_t store_limit;
...
};
A structure of this type is allocated by FS-Cache to record outstanding
writes to be made. FS-Cache itself enqueues this operation and invokes
the write_page() method on the object at appropriate times to effect
storage.
================
CACHE OPERATIONS
================
The cache backend provides FS-Cache with a table of operations that can be
performed on the denizens of the cache. These are held in a structure of type:
struct fscache_cache_ops
(*) Name of cache provider [mandatory]:
const char *name
This isn't strictly an operation, but should be pointed at a string naming
the backend.
(*) Allocate a new object [mandatory]:
struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
struct fscache_cookie *cookie)
This method is used to allocate a cache object representation to back a
cookie in a particular cache. fscache_object_init() should be called on
the object to initialise it prior to returning.
This function may also be used to parse the index key to be used for
multiple lookup calls to turn it into a more convenient form. FS-Cache
will call the lookup_complete() method to allow the cache to release the
form once lookup is complete or aborted.
(*) Look up and create object [mandatory]:
void (*lookup_object)(struct fscache_object *object)
This method is used to look up an object, given that the object is already
allocated and attached to the cookie. This should instantiate that object
in the cache if it can.
The method should call fscache_object_lookup_negative() as soon as
possible if it determines the object doesn't exist in the cache. If the
object is found to exist and the netfs indicates that it is valid then
fscache_obtained_object() should be called once the object is in a
position to have data stored in it. Similarly, fscache_obtained_object()
should also be called once a non-present object has been created.
If a lookup error occurs, fscache_object_lookup_error() should be called
to abort the lookup of that object.
(*) Release lookup data [mandatory]:
void (*lookup_complete)(struct fscache_object *object)
This method is called to ask the cache to release any resources it was
using to perform a lookup.
(*) Increment object refcount [mandatory]:
struct fscache_object *(*grab_object)(struct fscache_object *object)
This method is called to increment the reference count on an object. It
may fail (for instance if the cache is being withdrawn) by returning NULL.
It should return the object pointer if successful.
(*) Lock/Unlock object [mandatory]:
void (*lock_object)(struct fscache_object *object)
void (*unlock_object)(struct fscache_object *object)
These methods are used to exclusively lock an object. It must be possible
to schedule with the lock held, so a spinlock isn't sufficient.
(*) Pin/Unpin object [optional]:
int (*pin_object)(struct fscache_object *object)
void (*unpin_object)(struct fscache_object *object)
These methods are used to pin an object into the cache. Once pinned an
object cannot be reclaimed to make space. Return -ENOSPC if there's not
enough space in the cache to permit this.
(*) Update object [mandatory]:
int (*update_object)(struct fscache_object *object)
This is called to update the index entry for the specified object. The
new information should be in object->cookie->netfs_data. This can be
obtained by calling object->cookie->def->get_aux()/get_attr().
(*) Discard object [mandatory]:
void (*drop_object)(struct fscache_object *object)
This method is called to indicate that an object has been unbound from its
cookie, and that the cache should release the object's resources and
retire it if it's in state FSCACHE_OBJECT_RECYCLING.
This method should not attempt to release any references held by the
caller. The caller will invoke the put_object() method as appropriate.
(*) Release object reference [mandatory]:
void (*put_object)(struct fscache_object *object)
This method is used to discard a reference to an object. The object may
be freed when all the references to it are released.
(*) Synchronise a cache [mandatory]:
void (*sync)(struct fscache_cache *cache)
This is called to ask the backend to synchronise a cache with its backing
device.
(*) Dissociate a cache [mandatory]:
void (*dissociate_pages)(struct fscache_cache *cache)
This is called to ask a cache to perform any page dissociations as part of
cache withdrawal.
(*) Notification that the attributes on a netfs file changed [mandatory]:
int (*attr_changed)(struct fscache_object *object);
This is called to indicate to the cache that certain attributes on a netfs
file have changed (for example the maximum size a file may reach). The
cache can read these from the netfs by calling the cookie's get_attr()
method.
The cache may use the file size information to reserve space on the cache.
It should also call fscache_set_store_limit() to indicate to FS-Cache the
highest byte it's willing to store for an object.
This method may return -ve if an error occurred or the cache object cannot
be expanded. In such a case, the object will be withdrawn from service.
This operation is run asynchronously from FS-Cache's thread pool, and
storage and retrieval operations from the netfs are excluded during the
execution of this operation.
(*) Reserve cache space for an object's data [optional]:
int (*reserve_space)(struct fscache_object *object, loff_t size);
This is called to request that cache space be reserved to hold the data
for an object and the metadata used to track it. Zero size should be
taken as request to cancel a reservation.
This should return 0 if successful, -ENOSPC if there isn't enough space
available, or -ENOMEM or -EIO on other errors.
The reservation may exceed the current size of the object, thus permitting
future expansion. If the amount of space consumed by an object would
exceed the reservation, it's permitted to refuse requests to allocate
pages, but not required. An object may be pruned down to its reservation
size if larger than that already.
(*) Request page be read from cache [mandatory]:
int (*read_or_alloc_page)(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
This is called to attempt to read a netfs page from the cache, or to
reserve a backing block if not. FS-Cache will have done as much checking
as it can before calling, but most of the work belongs to the backend.
If there's no page in the cache, then -ENODATA should be returned if the
backend managed to reserve a backing block; -ENOBUFS or -ENOMEM if it
didn't.
If there is suitable data in the cache, then a read operation should be
queued and 0 returned. When the read finishes, fscache_end_io() should be
called.
The fscache_mark_pages_cached() should be called for the page if any cache
metadata is retained. This will indicate to the netfs that the page needs
explicit uncaching. This operation takes a pagevec, thus allowing several
pages to be marked at once.
The retrieval record pointed to by op should be retained for each page
queued and released when I/O on the page has been formally ended.
fscache_get/put_retrieval() are available for this purpose.
The retrieval record may be used to get CPU time via the FS-Cache thread
pool. If this is desired, the op->op.processor should be set to point to
the appropriate processing routine, and fscache_enqueue_retrieval() should
be called at an appropriate point to request CPU time. For instance, the
retrieval routine could be enqueued upon the completion of a disk read.
The to_do field in the retrieval record is provided to aid in this.
If an I/O error occurs, fscache_io_error() should be called and -ENOBUFS
returned if possible or fscache_end_io() called with a suitable error
code..
(*) Request pages be read from cache [mandatory]:
int (*read_or_alloc_pages)(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
This is like the read_or_alloc_page() method, except it is handed a list
of pages instead of one page. Any pages on which a read operation is
started must be added to the page cache for the specified mapping and also
to the LRU. Such pages must also be removed from the pages list and
*nr_pages decremented per page.
If there was an error such as -ENOMEM, then that should be returned; else
if one or more pages couldn't be read or allocated, then -ENOBUFS should
be returned; else if one or more pages couldn't be read, then -ENODATA
should be returned. If all the pages are dispatched then 0 should be
returned.
(*) Request page be allocated in the cache [mandatory]:
int (*allocate_page)(struct fscache_retrieval *op,
struct page *page,
gfp_t gfp)
This is like the read_or_alloc_page() method, except that it shouldn't
read from the cache, even if there's data there that could be retrieved.
It should, however, set up any internal metadata required such that
the write_page() method can write to the cache.
If there's no backing block available, then -ENOBUFS should be returned
(or -ENOMEM if there were other problems). If a block is successfully
allocated, then the netfs page should be marked and 0 returned.
(*) Request pages be allocated in the cache [mandatory]:
int (*allocate_pages)(struct fscache_retrieval *op,
struct list_head *pages,
unsigned *nr_pages,
gfp_t gfp)
This is an multiple page version of the allocate_page() method. pages and
nr_pages should be treated as for the read_or_alloc_pages() method.
(*) Request page be written to cache [mandatory]:
int (*write_page)(struct fscache_storage *op,
struct page *page);
This is called to write from a page on which there was a previously
successful read_or_alloc_page() call or similar. FS-Cache filters out
pages that don't have mappings.
This method is called asynchronously from the FS-Cache thread pool. It is
not required to actually store anything, provided -ENODATA is then
returned to the next read of this page.
If an error occurred, then a negative error code should be returned,
otherwise zero should be returned. FS-Cache will take appropriate action
in response to an error, such as withdrawing this object.
If this method returns success then FS-Cache will inform the netfs
appropriately.
(*) Discard retained per-page metadata [mandatory]:
void (*uncache_page)(struct fscache_object *object, struct page *page)
This is called when a netfs page is being evicted from the pagecache. The
cache backend should tear down any internal representation or tracking it
maintains for this page.
==================
FS-CACHE UTILITIES
==================
FS-Cache provides some utilities that a cache backend may make use of:
(*) Note occurrence of an I/O error in a cache:
void fscache_io_error(struct fscache_cache *cache)
This tells FS-Cache that an I/O error occurred in the cache. After this
has been called, only resource dissociation operations (object and page
release) will be passed from the netfs to the cache backend for the
specified cache.
This does not actually withdraw the cache. That must be done separately.
(*) Invoke the retrieval I/O completion function:
void fscache_end_io(struct fscache_retrieval *op, struct page *page,
int error);
This is called to note the end of an attempt to retrieve a page. The
error value should be 0 if successful and an error otherwise.
(*) Set highest store limit:
void fscache_set_store_limit(struct fscache_object *object,
loff_t i_size);
This sets the limit FS-Cache imposes on the highest byte it's willing to
try and store for a netfs. Any page over this limit is automatically
rejected by fscache_read_alloc_page() and co with -ENOBUFS.
(*) Mark pages as being cached:
void fscache_mark_pages_cached(struct fscache_retrieval *op,
struct pagevec *pagevec);
This marks a set of pages as being cached. After this has been called,
the netfs must call fscache_uncache_page() to unmark the pages.
(*) Perform coherency check on an object:
enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
const void *data,
uint16_t datalen);
This asks the netfs to perform a coherency check on an object that has
just been looked up. The cookie attached to the object will determine the
netfs to use. data and datalen should specify where the auxiliary data
retrieved from the cache can be found.
One of three values will be returned:
(*) FSCACHE_CHECKAUX_OKAY
The coherency data indicates the object is valid as is.
(*) FSCACHE_CHECKAUX_NEEDS_UPDATE
The coherency data needs updating, but otherwise the object is
valid.
(*) FSCACHE_CHECKAUX_OBSOLETE
The coherency data indicates that the object is obsolete and should
be discarded.
(*) Initialise a freshly allocated object:
void fscache_object_init(struct fscache_object *object);
This initialises all the fields in an object representation.
(*) Indicate the destruction of an object:
void fscache_object_destroyed(struct fscache_cache *cache);
This must be called to inform FS-Cache that an object that belonged to a
cache has been destroyed and deallocated. This will allow continuation
of the cache withdrawal process when it is stopped pending destruction of
all the objects.
(*) Indicate negative lookup on an object:
void fscache_object_lookup_negative(struct fscache_object *object);
This is called to indicate to FS-Cache that a lookup process for an object
found a negative result.
This changes the state of an object to permit reads pending on lookup
completion to go off and start fetching data from the netfs server as it's
known at this point that there can't be any data in the cache.
This may be called multiple times on an object. Only the first call is
significant - all subsequent calls are ignored.
(*) Indicate an object has been obtained:
void fscache_obtained_object(struct fscache_object *object);
This is called to indicate to FS-Cache that a lookup process for an object
produced a positive result, or that an object was created. This should
only be called once for any particular object.
This changes the state of an object to indicate:
(1) if no call to fscache_object_lookup_negative() has been made on
this object, that there may be data available, and that reads can
now go and look for it; and
(2) that writes may now proceed against this object.
(*) Indicate that object lookup failed:
void fscache_object_lookup_error(struct fscache_object *object);
This marks an object as having encountered a fatal error (usually EIO)
and causes it to move into a state whereby it will be withdrawn as soon
as possible.
(*) Get and release references on a retrieval record:
void fscache_get_retrieval(struct fscache_retrieval *op);
void fscache_put_retrieval(struct fscache_retrieval *op);
These two functions are used to retain a retrieval record whilst doing
asynchronous data retrieval and block allocation.
(*) Enqueue a retrieval record for processing.
void fscache_enqueue_retrieval(struct fscache_retrieval *op);
This enqueues a retrieval record for processing by the FS-Cache thread
pool. One of the threads in the pool will invoke the retrieval record's
op->op.processor callback function. This function may be called from
within the callback function.
(*) List of object state names:
const char *fscache_object_states[];
For debugging purposes, this may be used to turn the state that an object
is in into a text string for display purposes.

501
Documentation/filesystems/caching/cachefiles.txt Normal file
View file

@ -0,0 +1,501 @@
===============================================
CacheFiles: CACHE ON ALREADY MOUNTED FILESYSTEM
===============================================
Contents:
(*) Overview.
(*) Requirements.
(*) Configuration.
(*) Starting the cache.
(*) Things to avoid.
(*) Cache culling.
(*) Cache structure.
(*) Security model and SELinux.
(*) A note on security.
(*) Statistical information.
(*) Debugging.
========
OVERVIEW
========
CacheFiles is a caching backend that's meant to use as a cache a directory on
an already mounted filesystem of a local type (such as Ext3).
CacheFiles uses a userspace daemon to do some of the cache management - such as
reaping stale nodes and culling. This is called cachefilesd and lives in
/sbin.
The filesystem and data integrity of the cache are only as good as those of the
filesystem providing the backing services. Note that CacheFiles does not
attempt to journal anything since the journalling interfaces of the various
filesystems are very specific in nature.
CacheFiles creates a misc character device - "/dev/cachefiles" - that is used
to communication with the daemon. Only one thing may have this open at once,
and whilst it is open, a cache is at least partially in existence. The daemon
opens this and sends commands down it to control the cache.
CacheFiles is currently limited to a single cache.
CacheFiles attempts to maintain at least a certain percentage of free space on
the filesystem, shrinking the cache by culling the objects it contains to make
space if necessary - see the "Cache Culling" section. This means it can be
placed on the same medium as a live set of data, and will expand to make use of
spare space and automatically contract when the set of data requires more
space.
============
REQUIREMENTS
============
The use of CacheFiles and its daemon requires the following features to be
available in the system and in the cache filesystem:
- dnotify.
- extended attributes (xattrs).
- openat() and friends.
- bmap() support on files in the filesystem (FIBMAP ioctl).
- The use of bmap() to detect a partial page at the end of the file.
It is strongly recommended that the "dir_index" option is enabled on Ext3
filesystems being used as a cache.
=============
CONFIGURATION
=============
The cache is configured by a script in /etc/cachefilesd.conf. These commands
set up cache ready for use. The following script commands are available:
(*) brun <N>%
(*) bcull <N>%
(*) bstop <N>%
(*) frun <N>%
(*) fcull <N>%
(*) fstop <N>%
Configure the culling limits. Optional. See the section on culling
The defaults are 7% (run), 5% (cull) and 1% (stop) respectively.
The commands beginning with a 'b' are file space (block) limits, those
beginning with an 'f' are file count limits.
(*) dir <path>
Specify the directory containing the root of the cache. Mandatory.
(*) tag <name>
Specify a tag to FS-Cache to use in distinguishing multiple caches.
Optional. The default is "CacheFiles".
(*) debug <mask>
Specify a numeric bitmask to control debugging in the kernel module.
Optional. The default is zero (all off). The following values can be
OR'd into the mask to collect various information:
1 Turn on trace of function entry (_enter() macros)
2 Turn on trace of function exit (_leave() macros)
4 Turn on trace of internal debug points (_debug())
This mask can also be set through sysfs, eg:
echo 5 >/sys/modules/cachefiles/parameters/debug
==================
STARTING THE CACHE
==================
The cache is started by running the daemon. The daemon opens the cache device,
configures the cache and tells it to begin caching. At that point the cache
binds to fscache and the cache becomes live.
The daemon is run as follows:
/sbin/cachefilesd [-d]* [-s] [-n] [-f <configfile>]
The flags are:
(*) -d
Increase the debugging level. This can be specified multiple times and
is cumulative with itself.
(*) -s
Send messages to stderr instead of syslog.
(*) -n
Don't daemonise and go into background.
(*) -f <configfile>
Use an alternative configuration file rather than the default one.
===============
THINGS TO AVOID
===============
Do not mount other things within the cache as this will cause problems. The
kernel module contains its own very cut-down path walking facility that ignores
mountpoints, but the daemon can't avoid them.
Do not create, rename or unlink files and directories in the cache whilst the
cache is active, as this may cause the state to become uncertain.
Renaming files in the cache might make objects appear to be other objects (the
filename is part of the lookup key).
Do not change or remove the extended attributes attached to cache files by the
cache as this will cause the cache state management to get confused.
Do not create files or directories in the cache, lest the cache get confused or
serve incorrect data.
Do not chmod files in the cache. The module creates things with minimal
permissions to prevent random users being able to access them directly.
=============
CACHE CULLING
=============
The cache may need culling occasionally to make space. This involves
discarding objects from the cache that have been used less recently than
anything else. Culling is based on the access time of data objects. Empty
directories are culled if not in use.
Cache culling is done on the basis of the percentage of blocks and the
percentage of files available in the underlying filesystem. There are six
"limits":
(*) brun
(*) frun
If the amount of free space and the number of available files in the cache
rises above both these limits, then culling is turned off.
(*) bcull
(*) fcull
If the amount of available space or the number of available files in the
cache falls below either of these limits, then culling is started.
(*) bstop
(*) fstop
If the amount of available space or the number of available files in the
cache falls below either of these limits, then no further allocation of
disk space or files is permitted until culling has raised things above
these limits again.
These must be configured thusly:
0 <= bstop < bcull < brun < 100
0 <= fstop < fcull < frun < 100
Note that these are percentages of available space and available files, and do
_not_ appear as 100 minus the percentage displayed by the "df" program.
The userspace daemon scans the cache to build up a table of cullable objects.
These are then culled in least recently used order. A new scan of the cache is
started as soon as space is made in the table. Objects will be skipped if
their atimes have changed or if the kernel module says it is still using them.
===============
CACHE STRUCTURE
===============
The CacheFiles module will create two directories in the directory it was
given:
(*) cache/
(*) graveyard/
The active cache objects all reside in the first directory. The CacheFiles
kernel module moves any retired or culled objects that it can't simply unlink
to the graveyard from which the daemon will actually delete them.
The daemon uses dnotify to monitor the graveyard directory, and will delete
anything that appears therein.
The module represents index objects as directories with the filename "I..." or
"J...". Note that the "cache/" directory is itself a special index.
Data objects are represented as files if they have no children, or directories
if they do. Their filenames all begin "D..." or "E...". If represented as a
directory, data objects will have a file in the directory called "data" that
actually holds the data.
Special objects are similar to data objects, except their filenames begin
"S..." or "T...".
If an object has children, then it will be represented as a directory.
Immediately in the representative directory are a collection of directories
named for hash values of the child object keys with an '@' prepended. Into
this directory, if possible, will be placed the representations of the child
objects:
INDEX INDEX INDEX DATA FILES
========= ========== ================================= ================
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...DB1ry
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...N22ry
cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...FP1ry
If the key is so long that it exceeds NAME_MAX with the decorations added on to
it, then it will be cut into pieces, the first few of which will be used to
make a nest of directories, and the last one of which will be the objects
inside the last directory. The names of the intermediate directories will have
'+' prepended:
J1223/@23/+xy...z/+kl...m/Epqr
Note that keys are raw data, and not only may they exceed NAME_MAX in size,
they may also contain things like '/' and NUL characters, and so they may not
be suitable for turning directly into a filename.
To handle this, CacheFiles will use a suitably printable filename directly and
"base-64" encode ones that aren't directly suitable. The two versions of
object filenames indicate the encoding:
OBJECT TYPE PRINTABLE ENCODED
=============== =============== ===============
Index "I..." "J..."
Data "D..." "E..."
Special "S..." "T..."
Intermediate directories are always "@" or "+" as appropriate.
Each object in the cache has an extended attribute label that holds the object
type ID (required to distinguish special objects) and the auxiliary data from
the netfs. The latter is used to detect stale objects in the cache and update
or retire them.
Note that CacheFiles will erase from the cache any file it doesn't recognise or
any file of an incorrect type (such as a FIFO file or a device file).
==========================
SECURITY MODEL AND SELINUX
==========================
CacheFiles is implemented to deal properly with the LSM security features of
the Linux kernel and the SELinux facility.
One of the problems that CacheFiles faces is that it is generally acting on
behalf of a process, and running in that process's context, and that includes a
security context that is not appropriate for accessing the cache - either
because the files in the cache are inaccessible to that process, or because if
the process creates a file in the cache, that file may be inaccessible to other
processes.
The way CacheFiles works is to temporarily change the security context (fsuid,
fsgid and actor security label) that the process acts as - without changing the
security context of the process when it the target of an operation performed by
some other process (so signalling and suchlike still work correctly).
When the CacheFiles module is asked to bind to its cache, it:
(1) Finds the security label attached to the root cache directory and uses
that as the security label with which it will create files. By default,
this is:
cachefiles_var_t
(2) Finds the security label of the process which issued the bind request
(presumed to be the cachefilesd daemon), which by default will be:
cachefilesd_t
and asks LSM to supply a security ID as which it should act given the
daemon's label. By default, this will be:
cachefiles_kernel_t
SELinux transitions the daemon's security ID to the module's security ID
based on a rule of this form in the policy.
type_transition <daemon's-ID> kernel_t : process <module's-ID>;
For instance:
type_transition cachefilesd_t kernel_t : process cachefiles_kernel_t;
The module's security ID gives it permission to create, move and remove files
and directories in the cache, to find and access directories and files in the
cache, to set and access extended attributes on cache objects, and to read and
write files in the cache.
The daemon's security ID gives it only a very restricted set of permissions: it
may scan directories, stat files and erase files and directories. It may
not read or write files in the cache, and so it is precluded from accessing the
data cached therein; nor is it permitted to create new files in the cache.
There are policy source files available in:
http://people.redhat.com/~dhowells/fscache/cachefilesd-0.8.tar.bz2
and later versions. In that tarball, see the files:
cachefilesd.te
cachefilesd.fc
cachefilesd.if
They are built and installed directly by the RPM.
If a non-RPM based system is being used, then copy the above files to their own
directory and run:
make -f /usr/share/selinux/devel/Makefile
semodule -i cachefilesd.pp
You will need checkpolicy and selinux-policy-devel installed prior to the
build.
By default, the cache is located in /var/fscache, but if it is desirable that
it should be elsewhere, than either the above policy files must be altered, or
an auxiliary policy must be installed to label the alternate location of the
cache.
For instructions on how to add an auxiliary policy to enable the cache to be
located elsewhere when SELinux is in enforcing mode, please see:
/usr/share/doc/cachefilesd-*/move-cache.txt
When the cachefilesd rpm is installed; alternatively, the document can be found
in the sources.
==================
A NOTE ON SECURITY
==================
CacheFiles makes use of the split security in the task_struct. It allocates
its own task_security structure, and redirects current->act_as to point to it
when it acts on behalf of another process, in that process's context.
The reason it does this is that it calls vfs_mkdir() and suchlike rather than
bypassing security and calling inode ops directly. Therefore the VFS and LSM
may deny the CacheFiles access to the cache data because under some
circumstances the caching code is running in the security context of whatever
process issued the original syscall on the netfs.
Furthermore, should CacheFiles create a file or directory, the security
parameters with that object is created (UID, GID, security label) would be
derived from that process that issued the system call, thus potentially
preventing other processes from accessing the cache - including CacheFiles's
cache management daemon (cachefilesd).
What is required is to temporarily override the security of the process that
issued the system call. We can't, however, just do an in-place change of the
security data as that affects the process as an object, not just as a subject.
This means it may lose signals or ptrace events for example, and affects what
the process looks like in /proc.
So CacheFiles makes use of a logical split in the security between the
objective security (task->sec) and the subjective security (task->act_as). The
objective security holds the intrinsic security properties of a process and is
never overridden. This is what appears in /proc, and is what is used when a
process is the target of an operation by some other process (SIGKILL for
example).
The subjective security holds the active security properties of a process, and
may be overridden. This is not seen externally, and is used whan a process
acts upon another object, for example SIGKILLing another process or opening a
file.
LSM hooks exist that allow SELinux (or Smack or whatever) to reject a request
for CacheFiles to run in a context of a specific security label, or to create
files and directories with another security label.
=======================
STATISTICAL INFORMATION
=======================
If FS-Cache is compiled with the following option enabled:
CONFIG_CACHEFILES_HISTOGRAM=y
then it will gather certain statistics and display them through a proc file.
(*) /proc/fs/cachefiles/histogram
cat /proc/fs/cachefiles/histogram
JIFS SECS LOOKUPS MKDIRS CREATES
===== ===== ========= ========= =========
This shows the breakdown of the number of times each amount of time
between 0 jiffies and HZ-1 jiffies a variety of tasks took to run. The
columns are as follows:
COLUMN TIME MEASUREMENT
======= =======================================================
LOOKUPS Length of time to perform a lookup on the backing fs
MKDIRS Length of time to perform a mkdir on the backing fs
CREATES Length of time to perform a create on the backing fs
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
If CONFIG_CACHEFILES_DEBUG is enabled, the CacheFiles facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/cachefiles/parameters/debug
This is a bitmask of debugging streams to enable:
BIT VALUE STREAM POINT
======= ======= =============================== =======================
0 1 General Function entry trace
1 2 Function exit trace
2 4 General
The appropriate set of values should be OR'd together and the result written to
the control file. For example:
echo $((1|4|8)) >/sys/module/cachefiles/parameters/debug
will turn on all function entry debugging.

333
Documentation/filesystems/caching/fscache.txt Normal file
View file

@ -0,0 +1,333 @@
==========================
General Filesystem Caching
==========================
========
OVERVIEW
========
This facility is a general purpose cache for network filesystems, though it
could be used for caching other things such as ISO9660 filesystems too.
FS-Cache mediates between cache backends (such as CacheFS) and network
filesystems:
+---------+
| | +--------------+
| NFS |--+ | |
| | | +-->| CacheFS |
+---------+ | +----------+ | | /dev/hda5 |
| | | | +--------------+
+---------+ +-->| | |
| | | |--+
| AFS |----->| FS-Cache |
| | | |--+
+---------+ +-->| | |
| | | | +--------------+
+---------+ | +----------+ | | |
| | | +-->| CacheFiles |
| ISOFS |--+ | /var/cache |
| | +--------------+
+---------+
Or to look at it another way, FS-Cache is a module that provides a caching
facility to a network filesystem such that the cache is transparent to the
user:
+---------+
| |
| Server |
| |
+---------+
| NETWORK
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
| +----------+
V | |
+---------+ | |
| | | |
| NFS |----->| FS-Cache |
| | | |--+
+---------+ | | | +--------------+ +--------------+
| | | | | | | |
V +----------+ +-->| CacheFiles |-->| Ext3 |
+---------+ | /var/cache | | /dev/sda6 |
| | +--------------+ +--------------+
| VFS | ^ ^
| | | |
+---------+ +--------------+ |
| KERNEL SPACE | |
~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~|~~~~
| USER SPACE | |
V | |
+---------+ +--------------+
| | | |
| Process | | cachefilesd |
| | | |
+---------+ +--------------+
FS-Cache does not follow the idea of completely loading every netfs file
opened in its entirety into a cache before permitting it to be accessed and
then serving the pages out of that cache rather than the netfs inode because:
(1) It must be practical to operate without a cache.
(2) The size of any accessible file must not be limited to the size of the
cache.
(3) The combined size of all opened files (this includes mapped libraries)
must not be limited to the size of the cache.
(4) The user should not be forced to download an entire file just to do a
one-off access of a small portion of it (such as might be done with the
"file" program).
It instead serves the cache out in PAGE_SIZE chunks as and when requested by
the netfs('s) using it.
FS-Cache provides the following facilities:
(1) More than one cache can be used at once. Caches can be selected
explicitly by use of tags.
(2) Caches can be added / removed at any time.
(3) The netfs is provided with an interface that allows either party to
withdraw caching facilities from a file (required for (2)).
(4) The interface to the netfs returns as few errors as possible, preferring
rather to let the netfs remain oblivious.
(5) Cookies are used to represent indices, files and other objects to the
netfs. The simplest cookie is just a NULL pointer - indicating nothing
cached there.
(6) The netfs is allowed to propose - dynamically - any index hierarchy it
desires, though it must be aware that the index search function is
recursive, stack space is limited, and indices can only be children of
indices.
(7) Data I/O is done direct to and from the netfs's pages. The netfs
indicates that page A is at index B of the data-file represented by cookie
C, and that it should be read or written. The cache backend may or may
not start I/O on that page, but if it does, a netfs callback will be
invoked to indicate completion. The I/O may be either synchronous or
asynchronous.
(8) Cookies can be "retired" upon release. At this point FS-Cache will mark
them as obsolete and the index hierarchy rooted at that point will get
recycled.
(9) The netfs provides a "match" function for index searches. In addition to
saying whether a match was made or not, this can also specify that an
entry should be updated or deleted.
(10) As much as possible is done asynchronously.
FS-Cache maintains a virtual indexing tree in which all indices, files, objects
and pages are kept. Bits of this tree may actually reside in one or more
caches.
FSDEF
|
+------------------------------------+
| |
NFS AFS
| |
+--------------------------+ +-----------+
| | | |
homedir mirror afs.org redhat.com
| | |
+------------+ +---------------+ +----------+
| | | | | |
00001 00002 00007 00125 vol00001 vol00002
| | | | |
+---+---+ +-----+ +---+ +------+------+ +-----+----+
| | | | | | | | | | | | |
PG0 PG1 PG2 PG0 XATTR PG0 PG1 DIRENT DIRENT DIRENT R/W R/O Bak
| |
PG0 +-------+
| |
00001 00003
|
+---+---+
| | |
PG0 PG1 PG2
In the example above, you can see two netfs's being backed: NFS and AFS. These
have different index hierarchies:
(*) The NFS primary index contains per-server indices. Each server index is
indexed by NFS file handles to get data file objects. Each data file
objects can have an array of pages, but may also have further child
objects, such as extended attributes and directory entries. Extended
attribute objects themselves have page-array contents.
(*) The AFS primary index contains per-cell indices. Each cell index contains
per-logical-volume indices. Each of volume index contains up to three
indices for the read-write, read-only and backup mirrors of those volumes.
Each of these contains vnode data file objects, each of which contains an
array of pages.
The very top index is the FS-Cache master index in which individual netfs's
have entries.
Any index object may reside in more than one cache, provided it only has index
children. Any index with non-index object children will be assumed to only
reside in one cache.
The netfs API to FS-Cache can be found in:
Documentation/filesystems/caching/netfs-api.txt
The cache backend API to FS-Cache can be found in:
Documentation/filesystems/caching/backend-api.txt
A description of the internal representations and object state machine can be
found in:
Documentation/filesystems/caching/object.txt
=======================
STATISTICAL INFORMATION
=======================
If FS-Cache is compiled with the following options enabled:
CONFIG_FSCACHE_STATS=y
CONFIG_FSCACHE_HISTOGRAM=y
then it will gather certain statistics and display them through a number of
proc files.
(*) /proc/fs/fscache/stats
This shows counts of a number of events that can happen in FS-Cache:
CLASS EVENT MEANING
======= ======= =======================================================
Cookies idx=N Number of index cookies allocated
dat=N Number of data storage cookies allocated
spc=N Number of special cookies allocated
Objects alc=N Number of objects allocated
nal=N Number of object allocation failures
avl=N Number of objects that reached the available state
ded=N Number of objects that reached the dead state
ChkAux non=N Number of objects that didn't have a coherency check
ok=N Number of objects that passed a coherency check
upd=N Number of objects that needed a coherency data update
obs=N Number of objects that were declared obsolete
Pages mrk=N Number of pages marked as being cached
unc=N Number of uncache page requests seen
Acquire n=N Number of acquire cookie requests seen
nul=N Number of acq reqs given a NULL parent
noc=N Number of acq reqs rejected due to no cache available
ok=N Number of acq reqs succeeded
nbf=N Number of acq reqs rejected due to error
oom=N Number of acq reqs failed on ENOMEM
Lookups n=N Number of lookup calls made on cache backends
neg=N Number of negative lookups made
pos=N Number of positive lookups made
crt=N Number of objects created by lookup
Updates n=N Number of update cookie requests seen
nul=N Number of upd reqs given a NULL parent
run=N Number of upd reqs granted CPU time
Relinqs n=N Number of relinquish cookie requests seen
nul=N Number of rlq reqs given a NULL parent
wcr=N Number of rlq reqs waited on completion of creation
AttrChg n=N Number of attribute changed requests seen
ok=N Number of attr changed requests queued
nbf=N Number of attr changed rejected -ENOBUFS
oom=N Number of attr changed failed -ENOMEM
run=N Number of attr changed ops given CPU time
Allocs n=N Number of allocation requests seen
ok=N Number of successful alloc reqs
wt=N Number of alloc reqs that waited on lookup completion
nbf=N Number of alloc reqs rejected -ENOBUFS
ops=N Number of alloc reqs submitted
owt=N Number of alloc reqs waited for CPU time
Retrvls n=N Number of retrieval (read) requests seen
ok=N Number of successful retr reqs
wt=N Number of retr reqs that waited on lookup completion
nod=N Number of retr reqs returned -ENODATA
nbf=N Number of retr reqs rejected -ENOBUFS
int=N Number of retr reqs aborted -ERESTARTSYS
oom=N Number of retr reqs failed -ENOMEM
ops=N Number of retr reqs submitted
owt=N Number of retr reqs waited for CPU time
Stores n=N Number of storage (write) requests seen
ok=N Number of successful store reqs
agn=N Number of store reqs on a page already pending storage
nbf=N Number of store reqs rejected -ENOBUFS
oom=N Number of store reqs failed -ENOMEM
ops=N Number of store reqs submitted
run=N Number of store reqs granted CPU time
Ops pend=N Number of times async ops added to pending queues
run=N Number of times async ops given CPU time
enq=N Number of times async ops queued for processing
dfr=N Number of async ops queued for deferred release
rel=N Number of async ops released
gc=N Number of deferred-release async ops garbage collected
(*) /proc/fs/fscache/histogram
cat /proc/fs/fscache/histogram
JIFS SECS OBJ INST OP RUNS OBJ RUNS RETRV DLY RETRIEVLS
===== ===== ========= ========= ========= ========= =========
This shows the breakdown of the number of times each amount of time
between 0 jiffies and HZ-1 jiffies a variety of tasks took to run. The
columns are as follows:
COLUMN TIME MEASUREMENT
======= =======================================================
OBJ INST Length of time to instantiate an object
OP RUNS Length of time a call to process an operation took
OBJ RUNS Length of time a call to process an object event took
RETRV DLY Time between an requesting a read and lookup completing
RETRIEVLS Time between beginning and end of a retrieval
Each row shows the number of events that took a particular range of times.
Each step is 1 jiffy in size. The JIFS column indicates the particular
jiffy range covered, and the SECS field the equivalent number of seconds.
=========
DEBUGGING
=========
If CONFIG_FSCACHE_DEBUG is enabled, the FS-Cache facility can have runtime
debugging enabled by adjusting the value in:
/sys/module/fscache/parameters/debug
This is a bitmask of debugging streams to enable:
BIT VALUE STREAM POINT
======= ======= =============================== =======================
0 1 Cache management Function entry trace
1 2 Function exit trace
2 4 General
3 8 Cookie management Function entry trace
4 16 Function exit trace
5 32 General
6 64 Page handling Function entry trace
7 128 Function exit trace
8 256 General
9 512 Operation management Function entry trace
10 1024 Function exit trace
11 2048 General
The appropriate set of values should be OR'd together and the result written to
the control file. For example:
echo $((1|8|64)) >/sys/module/fscache/parameters/debug
will turn on all function entry debugging.

778
Documentation/filesystems/caching/netfs-api.txt Normal file
View file

@ -0,0 +1,778 @@
===============================
FS-CACHE NETWORK FILESYSTEM API
===============================
There's an API by which a network filesystem can make use of the FS-Cache
facilities. This is based around a number of principles:
(1) Caches can store a number of different object types. There are two main
object types: indices and files. The first is a special type used by
FS-Cache to make finding objects faster and to make retiring of groups of
objects easier.
(2) Every index, file or other object is represented by a cookie. This cookie
may or may not have anything associated with it, but the netfs doesn't
need to care.
(3) Barring the top-level index (one entry per cached netfs), the index
hierarchy for each netfs is structured according the whim of the netfs.
This API is declared in <linux/fscache.h>.
This document contains the following sections:
(1) Network filesystem definition
(2) Index definition
(3) Object definition
(4) Network filesystem (un)registration
(5) Cache tag lookup
(6) Index registration
(7) Data file registration
(8) Miscellaneous object registration
(9) Setting the data file size
(10) Page alloc/read/write
(11) Page uncaching
(12) Index and data file update
(13) Miscellaneous cookie operations
(14) Cookie unregistration
(15) Index and data file invalidation
(16) FS-Cache specific page flags.
=============================
NETWORK FILESYSTEM DEFINITION
=============================
FS-Cache needs a description of the network filesystem. This is specified
using a record of the following structure:
struct fscache_netfs {
uint32_t version;
const char *name;
struct fscache_cookie *primary_index;
...
};
This first two fields should be filled in before registration, and the third
will be filled in by the registration function; any other fields should just be
ignored and are for internal use only.
The fields are:
(1) The name of the netfs (used as the key in the toplevel index).
(2) The version of the netfs (if the name matches but the version doesn't, the
entire in-cache hierarchy for this netfs will be scrapped and begun
afresh).
(3) The cookie representing the primary index will be allocated according to
another parameter passed into the registration function.
For example, kAFS (linux/fs/afs/) uses the following definitions to describe
itself:
struct fscache_netfs afs_cache_netfs = {
.version = 0,
.name = "afs",
};
================
INDEX DEFINITION
================
Indices are used for two purposes:
(1) To aid the finding of a file based on a series of keys (such as AFS's
"cell", "volume ID", "vnode ID").
(2) To make it easier to discard a subset of all the files cached based around
a particular key - for instance to mirror the removal of an AFS volume.
However, since it's unlikely that any two netfs's are going to want to define
their index hierarchies in quite the same way, FS-Cache tries to impose as few
restraints as possible on how an index is structured and where it is placed in
the tree. The netfs can even mix indices and data files at the same level, but
it's not recommended.
Each index entry consists of a key of indeterminate length plus some auxilliary
data, also of indeterminate length.
There are some limits on indices:
(1) Any index containing non-index objects should be restricted to a single
cache. Any such objects created within an index will be created in the
first cache only. The cache in which an index is created can be
controlled by cache tags (see below).
(2) The entry data must be atomically journallable, so it is limited to about
400 bytes at present. At least 400 bytes will be available.
(3) The depth of the index tree should be judged with care as the search
function is recursive. Too many layers will run the kernel out of stack.
=================
OBJECT DEFINITION
=================
To define an object, a structure of the following type should be filled out:
struct fscache_cookie_def
{
uint8_t name[16];
uint8_t type;
struct fscache_cache_tag *(*select_cache)(
const void *parent_netfs_data,
const void *cookie_netfs_data);
uint16_t (*get_key)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
void (*get_attr)(const void *cookie_netfs_data,
uint64_t *size);
uint16_t (*get_aux)(const void *cookie_netfs_data,
void *buffer,
uint16_t bufmax);
enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
const void *data,
uint16_t datalen);
void (*get_context)(void *cookie_netfs_data, void *context);
void (*put_context)(void *cookie_netfs_data, void *context);
void (*mark_pages_cached)(void *cookie_netfs_data,
struct address_space *mapping,
struct pagevec *cached_pvec);
void (*now_uncached)(void *cookie_netfs_data);
};
This has the following fields:
(1) The type of the object [mandatory].
This is one of the following values:
(*) FSCACHE_COOKIE_TYPE_INDEX
This defines an index, which is a special FS-Cache type.
(*) FSCACHE_COOKIE_TYPE_DATAFILE
This defines an ordinary data file.
(*) Any other value between 2 and 255
This defines an extraordinary object such as an XATTR.
(2) The name of the object type (NUL terminated unless all 16 chars are used)
[optional].
(3) A function to select the cache in which to store an index [optional].
This function is invoked when an index needs to be instantiated in a cache
during the instantiation of a non-index object. Only the immediate index
parent for the non-index object will be queried. Any indices above that
in the hierarchy may be stored in multiple caches. This function does not
need to be supplied for any non-index object or any index that will only
have index children.
If this function is not supplied or if it returns NULL then the first
cache in the parent's list will be chosed, or failing that, the first
cache in the master list.
(4) A function to retrieve an object's key from the netfs [mandatory].
This function will be called with the netfs data that was passed to the
cookie acquisition function and the maximum length of key data that it may
provide. It should write the required key data into the given buffer and
return the quantity it wrote.
(5) A function to retrieve attribute data from the netfs [optional].
This function will be called with the netfs data that was passed to the
cookie acquisition function. It should return the size of the file if
this is a data file. The size may be used to govern how much cache must
be reserved for this file in the cache.
If the function is absent, a file size of 0 is assumed.
(6) A function to retrieve auxilliary data from the netfs [optional].
This function will be called with the netfs data that was passed to the
cookie acquisition function and the maximum length of auxilliary data that
it may provide. It should write the auxilliary data into the given buffer
and return the quantity it wrote.
If this function is absent, the auxilliary data length will be set to 0.
The length of the auxilliary data buffer may be dependent on the key
length. A netfs mustn't rely on being able to provide more than 400 bytes
for both.
(7) A function to check the auxilliary data [optional].
This function will be called to check that a match found in the cache for
this object is valid. For instance with AFS it could check the auxilliary
data against the data version number returned by the server to determine
whether the index entry in a cache is still valid.
If this function is absent, it will be assumed that matching objects in a
cache are always valid.
If present, the function should return one of the following values:
(*) FSCACHE_CHECKAUX_OKAY - the entry is okay as is
(*) FSCACHE_CHECKAUX_NEEDS_UPDATE - the entry requires update
(*) FSCACHE_CHECKAUX_OBSOLETE - the entry should be deleted
This function can also be used to extract data from the auxilliary data in
the cache and copy it into the netfs's structures.
(8) A pair of functions to manage contexts for the completion callback
[optional].
The cache read/write functions are passed a context which is then passed
to the I/O completion callback function. To ensure this context remains
valid until after the I/O completion is called, two functions may be
provided: one to get an extra reference on the context, and one to drop a
reference to it.
If the context is not used or is a type of object that won't go out of
scope, then these functions are not required. These functions are not
required for indices as indices may not contain data. These functions may
be called in interrupt context and so may not sleep.
(9) A function to mark a page as retaining cache metadata [optional].
This is called by the cache to indicate that it is retaining in-memory
information for this page and that the netfs should uncache the page when
it has finished. This does not indicate whether there's data on the disk
or not. Note that several pages at once may be presented for marking.
The PG_fscache bit is set on the pages before this function would be
called, so the function need not be provided if this is sufficient.
This function is not required for indices as they're not permitted data.
(10) A function to unmark all the pages retaining cache metadata [mandatory].
This is called by FS-Cache to indicate that a backing store is being
unbound from a cookie and that all the marks on the pages should be
cleared to prevent confusion. Note that the cache will have torn down all
its tracking information so that the pages don't need to be explicitly
uncached.
This function is not required for indices as they're not permitted data.
===================================
NETWORK FILESYSTEM (UN)REGISTRATION
===================================
The first step is to declare the network filesystem to the cache. This also
involves specifying the layout of the primary index (for AFS, this would be the
"cell" level).
The registration function is:
int fscache_register_netfs(struct fscache_netfs *netfs);
It just takes a pointer to the netfs definition. It returns 0 or an error as
appropriate.
For kAFS, registration is done as follows:
ret = fscache_register_netfs(&afs_cache_netfs);
The last step is, of course, unregistration:
void fscache_unregister_netfs(struct fscache_netfs *netfs);
================
CACHE TAG LOOKUP
================
FS-Cache permits the use of more than one cache. To permit particular index
subtrees to be bound to particular caches, the second step is to look up cache
representation tags. This step is optional; it can be left entirely up to
FS-Cache as to which cache should be used. The problem with doing that is that
FS-Cache will always pick the first cache that was registered.
To get the representation for a named tag:
struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name);
This takes a text string as the name and returns a representation of a tag. It
will never return an error. It may return a dummy tag, however, if it runs out
of memory; this will inhibit caching with this tag.
Any representation so obtained must be released by passing it to this function:
void fscache_release_cache_tag(struct fscache_cache_tag *tag);
The tag will be retrieved by FS-Cache when it calls the object definition
operation select_cache().
==================
INDEX REGISTRATION
==================
The third step is to inform FS-Cache about part of an index hierarchy that can
be used to locate files. This is done by requesting a cookie for each index in
the path to the file:
struct fscache_cookie *
fscache_acquire_cookie(struct fscache_cookie *parent,
const struct fscache_object_def *def,
void *netfs_data);
This function creates an index entry in the index represented by parent,
filling in the index entry by calling the operations pointed to by def.
Note that this function never returns an error - all errors are handled
internally. It may, however, return NULL to indicate no cookie. It is quite
acceptable to pass this token back to this function as the parent to another
acquisition (or even to the relinquish cookie, read page and write page
functions - see below).
Note also that no indices are actually created in a cache until a non-index
object needs to be created somewhere down the hierarchy. Furthermore, an index
may be created in several different caches independently at different times.
This is all handled transparently, and the netfs doesn't see any of it.
For example, with AFS, a cell would be added to the primary index. This index
entry would have a dependent inode containing a volume location index for the
volume mappings within this cell:
cell->cache =
fscache_acquire_cookie(afs_cache_netfs.primary_index,
&afs_cell_cache_index_def,
cell);
Then when a volume location was accessed, it would be entered into the cell's
index and an inode would be allocated that acts as a volume type and hash chain
combination:
vlocation->cache =
fscache_acquire_cookie(cell->cache,
&afs_vlocation_cache_index_def,
vlocation);
And then a particular flavour of volume (R/O for example) could be added to
that index, creating another index for vnodes (AFS inode equivalents):
volume->cache =
fscache_acquire_cookie(vlocation->cache,
&afs_volume_cache_index_def,
volume);
======================
DATA FILE REGISTRATION
======================
The fourth step is to request a data file be created in the cache. This is
identical to index cookie acquisition. The only difference is that the type in
the object definition should be something other than index type.
vnode->cache =
fscache_acquire_cookie(volume->cache,
&afs_vnode_cache_object_def,
vnode);
=================================
MISCELLANEOUS OBJECT REGISTRATION
=================================
An optional step is to request an object of miscellaneous type be created in
the cache. This is almost identical to index cookie acquisition. The only
difference is that the type in the object definition should be something other
than index type. Whilst the parent object could be an index, it's more likely
it would be some other type of object such as a data file.
xattr->cache =
fscache_acquire_cookie(vnode->cache,
&afs_xattr_cache_object_def,
xattr);
Miscellaneous objects might be used to store extended attributes or directory
entries for example.
==========================
SETTING THE DATA FILE SIZE
==========================
The fifth step is to set the physical attributes of the file, such as its size.
This doesn't automatically reserve any space in the cache, but permits the
cache to adjust its metadata for data tracking appropriately:
int fscache_attr_changed(struct fscache_cookie *cookie);
The cache will return -ENOBUFS if there is no backing cache or if there is no
space to allocate any extra metadata required in the cache. The attributes
will be accessed with the get_attr() cookie definition operation.
Note that attempts to read or write data pages in the cache over this size may
be rebuffed with -ENOBUFS.
This operation schedules an attribute adjustment to happen asynchronously at
some point in the future, and as such, it may happen after the function returns
to the caller. The attribute adjustment excludes read and write operations.
=====================
PAGE READ/ALLOC/WRITE
=====================
And the sixth step is to store and retrieve pages in the cache. There are
three functions that are used to do this.
Note:
(1) A page should not be re-read or re-allocated without uncaching it first.
(2) A read or allocated page must be uncached when the netfs page is released
from the pagecache.
(3) A page should only be written to the cache if previous read or allocated.
This permits the cache to maintain its page tracking in proper order.
PAGE READ
---------
Firstly, the netfs should ask FS-Cache to examine the caches and read the
contents cached for a particular page of a particular file if present, or else
allocate space to store the contents if not:
typedef
void (*fscache_rw_complete_t)(struct page *page,
void *context,
int error);
int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
struct page *page,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp);
The cookie argument must specify a cookie for an object that isn't an index,
the page specified will have the data loaded into it (and is also used to
specify the page number), and the gfp argument is used to control how any
memory allocations made are satisfied.
If the cookie indicates the inode is not cached:
(1) The function will return -ENOBUFS.
Else if there's a copy of the page resident in the cache:
(1) The mark_pages_cached() cookie operation will be called on that page.
(2) The function will submit a request to read the data from the cache's
backing device directly into the page specified.
(3) The function will return 0.
(4) When the read is complete, end_io_func() will be invoked with:
(*) The netfs data supplied when the cookie was created.
(*) The page descriptor.
(*) The context argument passed to the above function. This will be
maintained with the get_context/put_context functions mentioned above.
(*) An argument that's 0 on success or negative for an error code.
If an error occurs, it should be assumed that the page contains no usable
data.
end_io_func() will be called in process context if the read is results in
an error, but it might be called in interrupt context if the read is
successful.
Otherwise, if there's not a copy available in cache, but the cache may be able
to store the page:
(1) The mark_pages_cached() cookie operation will be called on that page.
(2) A block may be reserved in the cache and attached to the object at the
appropriate place.
(3) The function will return -ENODATA.
This function may also return -ENOMEM or -EINTR, in which case it won't have
read any data from the cache.
PAGE ALLOCATE
-------------
Alternatively, if there's not expected to be any data in the cache for a page
because the file has been extended, a block can simply be allocated instead:
int fscache_alloc_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp);
This is similar to the fscache_read_or_alloc_page() function, except that it
never reads from the cache. It will return 0 if a block has been allocated,
rather than -ENODATA as the other would. One or the other must be performed
before writing to the cache.
The mark_pages_cached() cookie operation will be called on the page if
successful.
PAGE WRITE
----------
Secondly, if the netfs changes the contents of the page (either due to an
initial download or if a user performs a write), then the page should be
written back to the cache:
int fscache_write_page(struct fscache_cookie *cookie,
struct page *page,
gfp_t gfp);
The cookie argument must specify a data file cookie, the page specified should
contain the data to be written (and is also used to specify the page number),
and the gfp argument is used to control how any memory allocations made are
satisfied.
The page must have first been read or allocated successfully and must not have
been uncached before writing is performed.
If the cookie indicates the inode is not cached then:
(1) The function will return -ENOBUFS.
Else if space can be allocated in the cache to hold this page:
(1) PG_fscache_write will be set on the page.
(2) The function will submit a request to write the data to cache's backing
device directly from the page specified.
(3) The function will return 0.
(4) When the write is complete PG_fscache_write is cleared on the page and
anyone waiting for that bit will be woken up.
Else if there's no space available in the cache, -ENOBUFS will be returned. It
is also possible for the PG_fscache_write bit to be cleared when no write took
place if unforeseen circumstances arose (such as a disk error).
Writing takes place asynchronously.
MULTIPLE PAGE READ
------------------
A facility is provided to read several pages at once, as requested by the
readpages() address space operation:
int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
struct address_space *mapping,
struct list_head *pages,
int *nr_pages,
fscache_rw_complete_t end_io_func,
void *context,
gfp_t gfp);
This works in a similar way to fscache_read_or_alloc_page(), except:
(1) Any page it can retrieve data for is removed from pages and nr_pages and
dispatched for reading to the disk. Reads of adjacent pages on disk may
be merged for greater efficiency.
(2) The mark_pages_cached() cookie operation will be called on several pages
at once if they're being read or allocated.
(3) If there was an general error, then that error will be returned.
Else if some pages couldn't be allocated or read, then -ENOBUFS will be
returned.
Else if some pages couldn't be read but were allocated, then -ENODATA will
be returned.
Otherwise, if all pages had reads dispatched, then 0 will be returned, the
list will be empty and *nr_pages will be 0.
(4) end_io_func will be called once for each page being read as the reads
complete. It will be called in process context if error != 0, but it may
be called in interrupt context if there is no error.
Note that a return of -ENODATA, -ENOBUFS or any other error does not preclude
some of the pages being read and some being allocated. Those pages will have
been marked appropriately and will need uncaching.
==============
PAGE UNCACHING
==============
To uncache a page, this function should be called:
void fscache_uncache_page(struct fscache_cookie *cookie,
struct page *page);
This function permits the cache to release any in-memory representation it
might be holding for this netfs page. This function must be called once for
each page on which the read or write page functions above have been called to
make sure the cache's in-memory tracking information gets torn down.
Note that pages can't be explicitly deleted from the a data file. The whole
data file must be retired (see the relinquish cookie function below).
Furthermore, note that this does not cancel the asynchronous read or write
operation started by the read/alloc and write functions, so the page
invalidation and release functions must use:
bool fscache_check_page_write(struct fscache_cookie *cookie,
struct page *page);
to see if a page is being written to the cache, and:
void fscache_wait_on_page_write(struct fscache_cookie *cookie,
struct page *page);
to wait for it to finish if it is.
==========================
INDEX AND DATA FILE UPDATE
==========================
To request an update of the index data for an index or other object, the
following function should be called:
void fscache_update_cookie(struct fscache_cookie *cookie);
This function will refer back to the netfs_data pointer stored in the cookie by
the acquisition function to obtain the data to write into each revised index
entry. The update method in the parent index definition will be called to
transfer the data.
Note that partial updates may happen automatically at other times, such as when
data blocks are added to a data file object.
===============================
MISCELLANEOUS COOKIE OPERATIONS
===============================
There are a number of operations that can be used to control cookies:
(*) Cookie pinning:
int fscache_pin_cookie(struct fscache_cookie *cookie);
void fscache_unpin_cookie(struct fscache_cookie *cookie);
These operations permit data cookies to be pinned into the cache and to
have the pinning removed. They are not permitted on index cookies.
The pinning function will return 0 if successful, -ENOBUFS in the cookie
isn't backed by a cache, -EOPNOTSUPP if the cache doesn't support pinning,
-ENOSPC if there isn't enough space to honour the operation, -ENOMEM or
-EIO if there's any other problem.
(*) Data space reservation:
int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size);
This permits a netfs to request cache space be reserved to store up to the
given amount of a file. It is permitted to ask for more than the current
size of the file to allow for future file expansion.
If size is given as zero then the reservation will be cancelled.
The function will return 0 if successful, -ENOBUFS in the cookie isn't
backed by a cache, -EOPNOTSUPP if the cache doesn't support reservations,
-ENOSPC if there isn't enough space to honour the operation, -ENOMEM or
-EIO if there's any other problem.
Note that this doesn't pin an object in a cache; it can still be culled to
make space if it's not in use.
=====================
COOKIE UNREGISTRATION
=====================
To get rid of a cookie, this function should be called.
void fscache_relinquish_cookie(struct fscache_cookie *cookie,
int retire);
If retire is non-zero, then the object will be marked for recycling, and all
copies of it will be removed from all active caches in which it is present.
Not only that but all child objects will also be retired.
If retire is zero, then the object may be available again when next the
acquisition function is called. Retirement here will overrule the pinning on a
cookie.
One very important note - relinquish must NOT be called for a cookie unless all
the cookies for "child" indices, objects and pages have been relinquished
first.
================================
INDEX AND DATA FILE INVALIDATION
================================
There is no direct way to invalidate an index subtree or a data file. To do
this, the caller should relinquish and retire the cookie they have, and then
acquire a new one.
===========================
FS-CACHE SPECIFIC PAGE FLAG
===========================
FS-Cache makes use of a page flag, PG_private_2, for its own purpose. This is
given the alternative name PG_fscache.
PG_fscache is used to indicate that the page is known by the cache, and that
the cache must be informed if the page is going to go away. It's an indication
to the netfs that the cache has an interest in this page, where an interest may
be a pointer to it, resources allocated or reserved for it, or I/O in progress
upon it.
The netfs can use this information in methods such as releasepage() to
determine whether it needs to uncache a page or update it.
Furthermore, if this bit is set, releasepage() and invalidatepage() operations
will be called on a page to get rid of it, even if PG_private is not set. This
allows caching to attempted on a page before read_cache_pages() to be called
after fscache_read_or_alloc_pages() as the former will try and release pages it
was given under certain circumstances.
This bit does not overlap with such as PG_private. This means that FS-Cache
can be used with a filesystem that uses the block buffering code.
There are a number of operations defined on this flag:
int PageFsCache(struct page *page);
void SetPageFsCache(struct page *page)
void ClearPageFsCache(struct page *page)
int TestSetPageFsCache(struct page *page)
int TestClearPageFsCache(struct page *page)
These functions are bit test, bit set, bit clear, bit test and set and bit
test and clear operations on PG_fscache.

313
Documentation/filesystems/caching/object.txt Normal file
View file

@ -0,0 +1,313 @@
====================================================
IN-KERNEL CACHE OBJECT REPRESENTATION AND MANAGEMENT
====================================================
By: David Howells <dhowells@redhat.com>
Contents:
(*) Representation
(*) Object management state machine.
- Provision of cpu time.
- Locking simplification.
(*) The set of states.
(*) The set of events.
==============
REPRESENTATION
==============
FS-Cache maintains an in-kernel representation of each object that a netfs is
currently interested in. Such objects are represented by the fscache_cookie
struct and are referred to as cookies.
FS-Cache also maintains a separate in-kernel representation of the objects that
a cache backend is currently actively caching. Such objects are represented by
the fscache_object struct. The cache backends allocate these upon request, and
are expected to embed them in their own representations. These are referred to
as objects.
There is a 1:N relationship between cookies and objects. A cookie may be
represented by multiple objects - an index may exist in more than one cache -
or even by no objects (it may not be cached).
Furthermore, both cookies and objects are hierarchical. The two hierarchies
correspond, but the cookies tree is a superset of the union of the object trees
of multiple caches:
NETFS INDEX TREE : CACHE 1 : CACHE 2
: :
: +-----------+ :
+----------->| IObject | :
+-----------+ | : +-----------+ :
| ICookie |-------+ : | :
+-----------+ | : | : +-----------+
| +------------------------------>| IObject |
| : | : +-----------+
| : V : |
| : +-----------+ : |
V +----------->| IObject | : |
+-----------+ | : +-----------+ : |
| ICookie |-------+ : | : V
+-----------+ | : | : +-----------+
| +------------------------------>| IObject |
+-----+-----+ : | : +-----------+
| | : | : |
V | : V : |
+-----------+ | : +-----------+ : |
| ICookie |------------------------->| IObject | : |
+-----------+ | : +-----------+ : |
| V : | : V
| +-----------+ : | : +-----------+
| | ICookie |-------------------------------->| IObject |
| +-----------+ : | : +-----------+
V | : V : |
+-----------+ | : +-----------+ : |
| DCookie |------------------------->| DObject | : |
+-----------+ | : +-----------+ : |
| : : |
+-------+-------+ : : |
| | : : |
V V : : V
+-----------+ +-----------+ : : +-----------+
| DCookie | | DCookie |------------------------>| DObject |
+-----------+ +-----------+ : : +-----------+
: :
In the above illustration, ICookie and IObject represent indices and DCookie
and DObject represent data storage objects. Indices may have representation in
multiple caches, but currently, non-index objects may not. Objects of any type
may also be entirely unrepresented.
As far as the netfs API goes, the netfs is only actually permitted to see
pointers to the cookies. The cookies themselves and any objects attached to
those cookies are hidden from it.
===============================
OBJECT MANAGEMENT STATE MACHINE
===============================
Within FS-Cache, each active object is managed by its own individual state
machine. The state for an object is kept in the fscache_object struct, in
object->state. A cookie may point to a set of objects that are in different
states.
Each state has an action associated with it that is invoked when the machine
wakes up in that state. There are four logical sets of states:
(1) Preparation: states that wait for the parent objects to become ready. The
representations are hierarchical, and it is expected that an object must
be created or accessed with respect to its parent object.
(2) Initialisation: states that perform lookups in the cache and validate
what's found and that create on disk any missing metadata.
(3) Normal running: states that allow netfs operations on objects to proceed
and that update the state of objects.
(4) Termination: states that detach objects from their netfs cookies, that
delete objects from disk, that handle disk and system errors and that free
up in-memory resources.
In most cases, transitioning between states is in response to signalled events.
When a state has finished processing, it will usually set the mask of events in
which it is interested (object->event_mask) and relinquish the worker thread.
Then when an event is raised (by calling fscache_raise_event()), if the event
is not masked, the object will be queued for processing (by calling
fscache_enqueue_object()).
PROVISION OF CPU TIME
---------------------
The work to be done by the various states is given CPU time by the threads of
the slow work facility (see Documentation/slow-work.txt). This is used in
preference to the workqueue facility because:
(1) Threads may be completely occupied for very long periods of time by a
particular work item. These state actions may be doing sequences of
synchronous, journalled disk accesses (lookup, mkdir, create, setxattr,
getxattr, truncate, unlink, rmdir, rename).
(2) Threads may do little actual work, but may rather spend a lot of time
sleeping on I/O. This means that single-threaded and 1-per-CPU-threaded
workqueues don't necessarily have the right numbers of threads.
LOCKING SIMPLIFICATION
----------------------
Because only one worker thread may be operating on any particular object's
state machine at once, this simplifies the locking, particularly with respect
to disconnecting the netfs's representation of a cache object (fscache_cookie)
from the cache backend's representation (fscache_object) - which may be
requested from either end.
=================
THE SET OF STATES
=================
The object state machine has a set of states that it can be in. There are
preparation states in which the object sets itself up and waits for its parent
object to transit to a state that allows access to its children:
(1) State FSCACHE_OBJECT_INIT.
Initialise the object and wait for the parent object to become active. In
the cache, it is expected that it will not be possible to look an object
up from the parent object, until that parent object itself has been looked
up.
There are initialisation states in which the object sets itself up and accesses
disk for the object metadata:
(2) State FSCACHE_OBJECT_LOOKING_UP.
Look up the object on disk, using the parent as a starting point.
FS-Cache expects the cache backend to probe the cache to see whether this
object is represented there, and if it is, to see if it's valid (coherency
management).
The cache should call fscache_object_lookup_negative() to indicate lookup
failure for whatever reason, and should call fscache_obtained_object() to
indicate success.
At the completion of lookup, FS-Cache will let the netfs go ahead with
read operations, no matter whether the file is yet cached. If not yet
cached, read operations will be immediately rejected with ENODATA until
the first known page is uncached - as to that point there can be no data
to be read out of the cache for that file that isn't currently also held
in the pagecache.
(3) State FSCACHE_OBJECT_CREATING.
Create an object on disk, using the parent as a starting point. This
happens if the lookup failed to find the object, or if the object's
coherency data indicated what's on disk is out of date. In this state,
FS-Cache expects the cache to create
The cache should call fscache_obtained_object() if creation completes
successfully, fscache_object_lookup_negative() otherwise.
At the completion of creation, FS-Cache will start processing write
operations the netfs has queued for an object. If creation failed, the
write ops will be transparently discarded, and nothing recorded in the
cache.
There are some normal running states in which the object spends its time
servicing netfs requests:
(4) State FSCACHE_OBJECT_AVAILABLE.
A transient state in which pending operations are started, child objects
are permitted to advance from FSCACHE_OBJECT_INIT state, and temporary
lookup data is freed.
(5) State FSCACHE_OBJECT_ACTIVE.
The normal running state. In this state, requests the netfs makes will be
passed on to the cache.
(6) State FSCACHE_OBJECT_UPDATING.
The state machine comes here to update the object in the cache from the
netfs's records. This involves updating the auxiliary data that is used
to maintain coherency.
And there are terminal states in which an object cleans itself up, deallocates
memory and potentially deletes stuff from disk:
(7) State FSCACHE_OBJECT_LC_DYING.
The object comes here if it is dying because of a lookup or creation
error. This would be due to a disk error or system error of some sort.
Temporary data is cleaned up, and the parent is released.
(8) State FSCACHE_OBJECT_DYING.
The object comes here if it is dying due to an error, because its parent
cookie has been relinquished by the netfs or because the cache is being
withdrawn.
Any child objects waiting on this one are given CPU time so that they too
can destroy themselves. This object waits for all its children to go away
before advancing to the next state.
(9) State FSCACHE_OBJECT_ABORT_INIT.
The object comes to this state if it was waiting on its parent in
FSCACHE_OBJECT_INIT, but its parent died. The object will destroy itself
so that the parent may proceed from the FSCACHE_OBJECT_DYING state.
(10) State FSCACHE_OBJECT_RELEASING.
(11) State FSCACHE_OBJECT_RECYCLING.
The object comes to one of these two states when dying once it is rid of
all its children, if it is dying because the netfs relinquished its
cookie. In the first state, the cached data is expected to persist, and
in the second it will be deleted.
(12) State FSCACHE_OBJECT_WITHDRAWING.
The object transits to this state if the cache decides it wants to
withdraw the object from service, perhaps to make space, but also due to
error or just because the whole cache is being withdrawn.
(13) State FSCACHE_OBJECT_DEAD.
The object transits to this state when the in-memory object record is
ready to be deleted. The object processor shouldn't ever see an object in
this state.
THE SET OF EVENTS
-----------------
There are a number of events that can be raised to an object state machine:
(*) FSCACHE_OBJECT_EV_UPDATE
The netfs requested that an object be updated. The state machine will ask
the cache backend to update the object, and the cache backend will ask the
netfs for details of the change through its cookie definition ops.
(*) FSCACHE_OBJECT_EV_CLEARED
This is signalled in two circumstances:
(a) when an object's last child object is dropped and
(b) when the last operation outstanding on an object is completed.
This is used to proceed from the dying state.
(*) FSCACHE_OBJECT_EV_ERROR
This is signalled when an I/O error occurs during the processing of some
object.
(*) FSCACHE_OBJECT_EV_RELEASE
(*) FSCACHE_OBJECT_EV_RETIRE
These are signalled when the netfs relinquishes a cookie it was using.
The event selected depends on whether the netfs asks for the backing
object to be retired (deleted) or retained.
(*) FSCACHE_OBJECT_EV_WITHDRAW
This is signalled when the cache backend wants to withdraw an object.
This means that the object will have to be detached from the netfs's
cookie.
Because the withdrawing releasing/retiring events are all handled by the object
state machine, it doesn't matter if there's a collision with both ends trying
to sever the connection at the same time. The state machine can just pick
which one it wants to honour, and that effects the other.

213
Documentation/filesystems/caching/operations.txt Normal file
View file

@ -0,0 +1,213 @@
================================
ASYNCHRONOUS OPERATIONS HANDLING
================================
By: David Howells <dhowells@redhat.com>
Contents:
(*) Overview.
(*) Operation record initialisation.
(*) Parameters.
(*) Procedure.
(*) Asynchronous callback.
========
OVERVIEW
========
FS-Cache has an asynchronous operations handling facility that it uses for its
data storage and retrieval routines. Its operations are represented by
fscache_operation structs, though these are usually embedded into some other
structure.
This facility is available to and expected to be be used by the cache backends,
and FS-Cache will create operations and pass them off to the appropriate cache
backend for completion.
To make use of this facility, <linux/fscache-cache.h> should be #included.
===============================
OPERATION RECORD INITIALISATION
===============================
An operation is recorded in an fscache_operation struct:
struct fscache_operation {
union {
struct work_struct fast_work;
struct slow_work slow_work;
};
unsigned long flags;
fscache_operation_processor_t processor;
...
};
Someone wanting to issue an operation should allocate something with this
struct embedded in it. They should initialise it by calling:
void fscache_operation_init(struct fscache_operation *op,
fscache_operation_release_t release);
with the operation to be initialised and the release function to use.
The op->flags parameter should be set to indicate the CPU time provision and
the exclusivity (see the Parameters section).
The op->fast_work, op->slow_work and op->processor flags should be set as
appropriate for the CPU time provision (see the Parameters section).
FSCACHE_OP_WAITING may be set in op->flags prior to each submission of the
operation and waited for afterwards.
==========
PARAMETERS
==========
There are a number of parameters that can be set in the operation record's flag
parameter. There are three options for the provision of CPU time in these
operations:
(1) The operation may be done synchronously (FSCACHE_OP_MYTHREAD). A thread
may decide it wants to handle an operation itself without deferring it to
another thread.
This is, for example, used in read operations for calling readpages() on
the backing filesystem in CacheFiles. Although readpages() does an
asynchronous data fetch, the determination of whether pages exist is done
synchronously - and the netfs does not proceed until this has been
determined.
If this option is to be used, FSCACHE_OP_WAITING must be set in op->flags
before submitting the operation, and the operating thread must wait for it
to be cleared before proceeding:
wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
fscache_wait_bit, TASK_UNINTERRUPTIBLE);
(2) The operation may be fast asynchronous (FSCACHE_OP_FAST), in which case it
will be given to keventd to process. Such an operation is not permitted
to sleep on I/O.
This is, for example, used by CacheFiles to copy data from a backing fs
page to a netfs page after the backing fs has read the page in.
If this option is used, op->fast_work and op->processor must be
initialised before submitting the operation:
INIT_WORK(&op->fast_work, do_some_work);
(3) The operation may be slow asynchronous (FSCACHE_OP_SLOW), in which case it
will be given to the slow work facility to process. Such an operation is
permitted to sleep on I/O.
This is, for example, used by FS-Cache to handle background writes of
pages that have just been fetched from a remote server.
If this option is used, op->slow_work and op->processor must be
initialised before submitting the operation:
fscache_operation_init_slow(op, processor)
Furthermore, operations may be one of two types:
(1) Exclusive (FSCACHE_OP_EXCLUSIVE). Operations of this type may not run in
conjunction with any other operation on the object being operated upon.
An example of this is the attribute change operation, in which the file
being written to may need truncation.
(2) Shareable. Operations of this type may be running simultaneously. It's
up to the operation implementation to prevent interference between other
operations running at the same time.
=========
PROCEDURE
=========
Operations are used through the following procedure:
(1) The submitting thread must allocate the operation and initialise it
itself. Normally this would be part of a more specific structure with the
generic op embedded within.
(2) The submitting thread must then submit the operation for processing using
one of the following two functions:
int fscache_submit_op(struct fscache_object *object,
struct fscache_operation *op);
int fscache_submit_exclusive_op(struct fscache_object *object,
struct fscache_operation *op);
The first function should be used to submit non-exclusive ops and the
second to submit exclusive ones. The caller must still set the
FSCACHE_OP_EXCLUSIVE flag.
If successful, both functions will assign the operation to the specified
object and return 0. -ENOBUFS will be returned if the object specified is
permanently unavailable.
The operation manager will defer operations on an object that is still
undergoing lookup or creation. The operation will also be deferred if an
operation of conflicting exclusivity is in progress on the object.
If the operation is asynchronous, the manager will retain a reference to
it, so the caller should put their reference to it by passing it to:
void fscache_put_operation(struct fscache_operation *op);
(3) If the submitting thread wants to do the work itself, and has marked the
operation with FSCACHE_OP_MYTHREAD, then it should monitor
FSCACHE_OP_WAITING as described above and check the state of the object if
necessary (the object might have died whilst the thread was waiting).
When it has finished doing its processing, it should call
fscache_put_operation() on it.
(4) The operation holds an effective lock upon the object, preventing other
exclusive ops conflicting until it is released. The operation can be
enqueued for further immediate asynchronous processing by adjusting the
CPU time provisioning option if necessary, eg:
op->flags &= ~FSCACHE_OP_TYPE;
op->flags |= ~FSCACHE_OP_FAST;
and calling:
void fscache_enqueue_operation(struct fscache_operation *op)
This can be used to allow other things to have use of the worker thread
pools.
=====================
ASYNCHRONOUS CALLBACK
=====================
When used in asynchronous mode, the worker thread pool will invoke the
processor method with a pointer to the operation. This should then get at the
container struct by using container_of():
static void fscache_write_op(struct fscache_operation *_op)
{
struct fscache_storage *op =
container_of(_op, struct fscache_storage, op);
...
}
The caller holds a reference on the operation, and will invoke
fscache_put_operation() when the processor function returns. The processor
function is at liberty to call fscache_enqueue_operation() or to take extra
references.

176
Documentation/filesystems/exofs.txt Normal file
View file

@ -0,0 +1,176 @@
===============================================================================
WHAT IS EXOFS?
===============================================================================
exofs is a file system that uses an OSD and exports the API of a normal Linux
file system. Users access exofs like any other local file system, and exofs
will in turn issue commands to the local OSD initiator.
OSD is a new T10 command set that views storage devices not as a large/flat
array of sectors but as a container of objects, each having a length, quota,
time attributes and more. Each object is addressed by a 64bit ID, and is
contained in a 64bit ID partition. Each object has associated attributes
attached to it, which are integral part of the object and provide metadata about
the object. The standard defines some common obligatory attributes, but user
attributes can be added as needed.
===============================================================================
ENVIRONMENT
===============================================================================
To use this file system, you need to have an object store to run it on. You
may download a target from:
http://open-osd.org
See Documentation/scsi/osd.txt for how to setup a working osd environment.
===============================================================================
USAGE
===============================================================================
1. Download and compile exofs and open-osd initiator:
You need an external Kernel source tree or kernel headers from your
distribution. (anything based on 2.6.26 or later).
a. download open-osd including exofs source using:
[parent-directory]$ git clone git://git.open-osd.org/open-osd.git
b. Build the library module like this:
[parent-directory]$ make -C KSRC=$(KER_DIR) open-osd
This will build both the open-osd initiator as well as the exofs kernel
module. Use whatever parameters you compiled your Kernel with and
$(KER_DIR) above pointing to the Kernel you compile against. See the file
open-osd/top-level-Makefile for an example.
2. Get the OSD initiator and target set up properly, and login to the target.
See Documentation/scsi/osd.txt for farther instructions. Also see ./do-osd
for example script that does all these steps.
3. Insmod the exofs.ko module:
[exofs]$ insmod exofs.ko
4. Make sure the directory where you want to mount exists. If not, create it.
(For example, mkdir /mnt/exofs)
5. At first run you will need to invoke the mkfs.exofs application
As an example, this will create the file system on:
/dev/osd0 partition ID 65536
mkfs.exofs --pid=65536 --format /dev/osd0
The --format is optional if not specified no OSD_FORMAT will be
preformed and a clean file system will be created in the specified pid,
in the available space of the target. (Use --format=size_in_meg to limit
the total LUN space available)
If pid already exist it will be deleted and a new one will be created in it's
place. Be careful.
An exofs lives inside a single OSD partition. You can create multiple exofs
filesystems on the same device using multiple pids.
(run mkfs.exofs without any parameters for usage help message)
6. Mount the file system.
For example, to mount /dev/osd0, partition ID 0x10000 on /mnt/exofs:
mount -t exofs -o pid=65536 /dev/osd0 /mnt/exofs/
7. For reference (See do-exofs example script):
do-exofs start - an example of how to perform the above steps.
do-exofs stop - an example of how to unmount the file system.
do-exofs format - an example of how to format and mkfs a new exofs.
8. Extra compilation flags (uncomment in fs/exofs/Kbuild):
CONFIG_EXOFS_DEBUG - for debug messages and extra checks.
===============================================================================
exofs mount options
===============================================================================
Similar to any mount command:
mount -t exofs -o exofs_options /dev/osdX mount_exofs_directory
Where:
-t exofs: specifies the exofs file system
/dev/osdX: X is a decimal number. /dev/osdX was created after a successful
login into an OSD target.
mount_exofs_directory: The directory to mount the file system on
exofs specific options: Options are separated by commas (,)
pid=<integer> - The partition number to mount/create as
container of the filesystem.
This option is mandatory
to=<integer> - Timeout in ticks for a single command
default is (60 * HZ) [for debugging only]
===============================================================================
DESIGN
===============================================================================
* The file system control block (AKA on-disk superblock) resides in an object
with a special ID (defined in common.h).
Information included in the file system control block is used to fill the
in-memory superblock structure at mount time. This object is created before
the file system is used by mkexofs.c It contains information such as:
- The file system's magic number
- The next inode number to be allocated
* Each file resides in its own object and contains the data (and it will be
possible to extend the file over multiple objects, though this has not been
implemented yet).
* A directory is treated as a file, and essentially contains a list of <file
name, inode #> pairs for files that are found in that directory. The object
IDs correspond to the files' inode numbers and will be allocated according to
a bitmap (stored in a separate object). Now they are allocated using a
counter.
* Each file's control block (AKA on-disk inode) is stored in its object's
attributes. This applies to both regular files and other types (directories,
device files, symlinks, etc.).
* Credentials are generated per object (inode and superblock) when they is
created in memory (read off disk or created). The credential works for all
operations and is used as long as the object remains in memory.
* Async OSD operations are used whenever possible, but the target may execute
them out of order. The operations that concern us are create, delete,
readpage, writepage, update_inode, and truncate. The following pairs of
operations should execute in the order written, and we need to prevent them
from executing in reverse order:
- The following are handled with the OBJ_CREATED and OBJ_2BCREATED
flags. OBJ_CREATED is set when we know the object exists on the OSD -
in create's callback function, and when we successfully do a read_inode.
OBJ_2BCREATED is set in the beginning of the create function, so we
know that we should wait.
- create/delete: delete should wait until the object is created
on the OSD.
- create/readpage: readpage should be able to return a page
full of zeroes in this case. If there was a write already
en-route (i.e. create, writepage, readpage) then the page
would be locked, and so it would really be the same as
create/writepage.
- create/writepage: if writepage is called for a sync write, it
should wait until the object is created on the OSD.
Otherwise, it should just return.
- create/truncate: truncate should wait until the object is
created on the OSD.
- create/update_inode: update_inode should wait until the
object is created on the OSD.
- Handled by VFS locks:
- readpage/delete: shouldn't happen because of page lock.
- writepage/delete: shouldn't happen because of page lock.
- readpage/writepage: shouldn't happen because of page lock.
===============================================================================
LICENSE/COPYRIGHT
===============================================================================
The exofs file system is based on ext2 v0.5b (distributed with the Linux kernel
version 2.6.10). All files include the original copyrights, and the license
is GPL version 2 (only version 2, as is true for the Linux kernel). The
Linux kernel can be downloaded from www.kernel.org.

14
Documentation/filesystems/ext3.txt
View file

@ -14,6 +14,11 @@ Options
When mounting an ext3 filesystem, the following option are accepted:
(*) == default
ro Mount filesystem read only. Note that ext3 will replay
the journal (and thus write to the partition) even when
mounted "read only". Mount options "ro,noload" can be
used to prevent writes to the filesystem.
journal=update Update the ext3 file system's journal to the current
format.
@ -27,7 +32,9 @@ journal_dev=devnum When the external journal device's major/minor numbers
identified through its new major/minor numbers encoded
in devnum.
noload Don't load the journal on mounting.
noload Don't load the journal on mounting. Note that this forces
mount of inconsistent filesystem, which can lead to
various problems.
data=journal All data are committed into the journal prior to being
written into the main file system.
@ -92,9 +99,12 @@ nocheck
debug Extra debugging information is sent to syslog.
errors=remount-ro(*) Remount the filesystem read-only on an error.
errors=remount-ro Remount the filesystem read-only on an error.
errors=continue Keep going on a filesystem error.
errors=panic Panic and halt the machine if an error occurs.
(These mount options override the errors behavior
specified in the superblock, which can be
configured using tune2fs.)
data_err=ignore(*) Just print an error message if an error occurs
in a file data buffer in ordered mode.

30
Documentation/filesystems/ext4.txt
View file

@ -85,7 +85,7 @@ Note: More extensive information for getting started with ext4 can be
* extent format more robust in face of on-disk corruption due to magics,
* internal redundancy in tree
* improved file allocation (multi-block alloc)
* fix 32000 subdirectory limit
* lift 32000 subdirectory limit imposed by i_links_count[1]
* nsec timestamps for mtime, atime, ctime, create time
* inode version field on disk (NFSv4, Lustre)
* reduced e2fsck time via uninit_bg feature
@ -100,6 +100,9 @@ Note: More extensive information for getting started with ext4 can be
* efficent new ordered mode in JBD2 and ext4(avoid using buffer head to force
the ordering)
[1] Filesystems with a block size of 1k may see a limit imposed by the
directory hash tree having a maximum depth of two.
2.2 Candidate features for future inclusion
* Online defrag (patches available but not well tested)
@ -180,8 +183,8 @@ commit=nrsec (*) Ext4 can be told to sync all its data and metadata
performance.
barrier=<0|1(*)> This enables/disables the use of write barriers in
the jbd code. barrier=0 disables, barrier=1 enables.
This also requires an IO stack which can support
barrier(*) the jbd code. barrier=0 disables, barrier=1 enables.
nobarrier This also requires an IO stack which can support
barriers, and if jbd gets an error on a barrier
write, it will disable again with a warning.
Write barriers enforce proper on-disk ordering
@ -189,6 +192,9 @@ barrier=<0|1(*)> This enables/disables the use of write barriers in
safe to use, at some performance penalty. If
your disks are battery-backed in one way or another,
disabling barriers may safely improve performance.
The mount options "barrier" and "nobarrier" can
also be used to enable or disable barriers, for
consistency with other ext4 mount options.
inode_readahead=n This tuning parameter controls the maximum
number of inode table blocks that ext4's inode
@ -310,6 +316,24 @@ journal_ioprio=prio The I/O priority (from 0 to 7, where 0 is the
a slightly higher priority than the default I/O
priority.
auto_da_alloc(*) Many broken applications don't use fsync() when
noauto_da_alloc replacing existing files via patterns such as
fd = open("foo.new")/write(fd,..)/close(fd)/
rename("foo.new", "foo"), or worse yet,
fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
If auto_da_alloc is enabled, ext4 will detect
the replace-via-rename and replace-via-truncate
patterns and force that any delayed allocation
blocks are allocated such that at the next
journal commit, in the default data=ordered
mode, the data blocks of the new file are forced
to disk before the rename() operation is
commited. This provides roughly the same level
of guarantees as ext3, and avoids the
"zero-length" problem that can happen when a
system crashes before the delayed allocation
blocks are forced to disk.
Data Mode
=========
There are 3 different data modes:

159
Documentation/filesystems/knfsd-stats.txt Normal file
View file

@ -0,0 +1,159 @@
Kernel NFS Server Statistics
============================
This document describes the format and semantics of the statistics
which the kernel NFS server makes available to userspace. These
statistics are available in several text form pseudo files, each of
which is described separately below.
In most cases you don't need to know these formats, as the nfsstat(8)
program from the nfs-utils distribution provides a helpful command-line
interface for extracting and printing them.
All the files described here are formatted as a sequence of text lines,
separated by newline '\n' characters. Lines beginning with a hash
'#' character are comments intended for humans and should be ignored
by parsing routines. All other lines contain a sequence of fields
separated by whitespace.
/proc/fs/nfsd/pool_stats
------------------------
This file is available in kernels from 2.6.30 onwards, if the
/proc/fs/nfsd filesystem is mounted (it almost always should be).
The first line is a comment which describes the fields present in
all the other lines. The other lines present the following data as
a sequence of unsigned decimal numeric fields. One line is shown
for each NFS thread pool.
All counters are 64 bits wide and wrap naturally. There is no way
to zero these counters, instead applications should do their own
rate conversion.
pool
The id number of the NFS thread pool to which this line applies.
This number does not change.
Thread pool ids are a contiguous set of small integers starting
at zero. The maximum value depends on the thread pool mode, but
currently cannot be larger than the number of CPUs in the system.
Note that in the default case there will be a single thread pool
which contains all the nfsd threads and all the CPUs in the system,
and thus this file will have a single line with a pool id of "0".
packets-arrived
Counts how many NFS packets have arrived. More precisely, this
is the number of times that the network stack has notified the
sunrpc server layer that new data may be available on a transport
(e.g. an NFS or UDP socket or an NFS/RDMA endpoint).
Depending on the NFS workload patterns and various network stack
effects (such as Large Receive Offload) which can combine packets
on the wire, this may be either more or less than the number
of NFS calls received (which statistic is available elsewhere).
However this is a more accurate and less workload-dependent measure
of how much CPU load is being placed on the sunrpc server layer
due to NFS network traffic.
sockets-enqueued
Counts how many times an NFS transport is enqueued to wait for
an nfsd thread to service it, i.e. no nfsd thread was considered
available.
The circumstance this statistic tracks indicates that there was NFS
network-facing work to be done but it couldn't be done immediately,
thus introducing a small delay in servicing NFS calls. The ideal
rate of change for this counter is zero; significantly non-zero
values may indicate a performance limitation.
This can happen either because there are too few nfsd threads in the
thread pool for the NFS workload (the workload is thread-limited),
or because the NFS workload needs more CPU time than is available in
the thread pool (the workload is CPU-limited). In the former case,
configuring more nfsd threads will probably improve the performance
of the NFS workload. In the latter case, the sunrpc server layer is
already choosing not to wake idle nfsd threads because there are too
many nfsd threads which want to run but cannot, so configuring more
nfsd threads will make no difference whatsoever. The overloads-avoided
statistic (see below) can be used to distinguish these cases.
threads-woken
Counts how many times an idle nfsd thread is woken to try to
receive some data from an NFS transport.
This statistic tracks the circumstance where incoming
network-facing NFS work is being handled quickly, which is a good
thing. The ideal rate of change for this counter will be close
to but less than the rate of change of the packets-arrived counter.
overloads-avoided
Counts how many times the sunrpc server layer chose not to wake an
nfsd thread, despite the presence of idle nfsd threads, because
too many nfsd threads had been recently woken but could not get
enough CPU time to actually run.
This statistic counts a circumstance where the sunrpc layer
heuristically avoids overloading the CPU scheduler with too many
runnable nfsd threads. The ideal rate of change for this counter
is zero. Significant non-zero values indicate that the workload
is CPU limited. Usually this is associated with heavy CPU usage
on all the CPUs in the nfsd thread pool.
If a sustained large overloads-avoided rate is detected on a pool,
the top(1) utility should be used to check for the following
pattern of CPU usage on all the CPUs associated with the given
nfsd thread pool.
- %us ~= 0 (as you're *NOT* running applications on your NFS server)
- %wa ~= 0
- %id ~= 0
- %sy + %hi + %si ~= 100
If this pattern is seen, configuring more nfsd threads will *not*
improve the performance of the workload. If this patten is not
seen, then something more subtle is wrong.
threads-timedout
Counts how many times an nfsd thread triggered an idle timeout,
i.e. was not woken to handle any incoming network packets for
some time.
This statistic counts a circumstance where there are more nfsd
threads configured than can be used by the NFS workload. This is
a clue that the number of nfsd threads can be reduced without
affecting performance. Unfortunately, it's only a clue and not
a strong indication, for a couple of reasons:
- Currently the rate at which the counter is incremented is quite
slow; the idle timeout is 60 minutes. Unless the NFS workload
remains constant for hours at a time, this counter is unlikely
to be providing information that is still useful.
- It is usually a wise policy to provide some slack,
i.e. configure a few more nfsds than are currently needed,
to allow for future spikes in load.
Note that incoming packets on NFS transports will be dealt with in
one of three ways. An nfsd thread can be woken (threads-woken counts
this case), or the transport can be enqueued for later attention
(sockets-enqueued counts this case), or the packet can be temporarily
deferred because the transport is currently being used by an nfsd
thread. This last case is not very interesting and is not explicitly
counted, but can be inferred from the other counters thus:
packets-deferred = packets-arrived - ( sockets-enqueued + threads-woken )
More
----
Descriptions of the other statistics file should go here.
Greg Banks <gnb@sgi.com>
26 Mar 2009

161
Documentation/filesystems/nfs41-server.txt Normal file
View file

@ -0,0 +1,161 @@
NFSv4.1 Server Implementation
Server support for minorversion 1 can be controlled using the
/proc/fs/nfsd/versions control file. The string output returned
by reading this file will contain either "+4.1" or "-4.1"
correspondingly.
Currently, server support for minorversion 1 is disabled by default.
It can be enabled at run time by writing the string "+4.1" to
the /proc/fs/nfsd/versions control file. Note that to write this
control file, the nfsd service must be taken down. Use your user-mode
nfs-utils to set this up; see rpc.nfsd(8)
The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
on the latest NFSv4.1 Internet Draft:
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29
From the many new features in NFSv4.1 the current implementation
focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
"exactly once" semantics and better control and throttling of the
resources allocated for each client.
Other NFSv4.1 features, Parallel NFS operations in particular,
are still under development out of tree.
See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
for more information.
The table below, taken from the NFSv4.1 document, lists
the operations that are mandatory to implement (REQ), optional
(OPT), and NFSv4.0 operations that are required not to implement (MNI)
in minor version 1. The first column indicates the operations that
are not supported yet by the linux server implementation.
The OPTIONAL features identified and their abbreviations are as follows:
pNFS Parallel NFS
FDELG File Delegations
DDELG Directory Delegations
The following abbreviations indicate the linux server implementation status.
I Implemented NFSv4.1 operations.
NS Not Supported.
NS* unimplemented optional feature.
P pNFS features implemented out of tree.
PNS pNFS features that are not supported yet (out of tree).
Operations
+----------------------+------------+--------------+----------------+
| Operation | REQ, REC, | Feature | Definition |
| | OPT, or | (REQ, REC, | |
| | MNI | or OPT) | |
+----------------------+------------+--------------+----------------+
| ACCESS | REQ | | Section 18.1 |
NS | BACKCHANNEL_CTL | REQ | | Section 18.33 |
NS | BIND_CONN_TO_SESSION | REQ | | Section 18.34 |
| CLOSE | REQ | | Section 18.2 |
| COMMIT | REQ | | Section 18.3 |
| CREATE | REQ | | Section 18.4 |
I | CREATE_SESSION | REQ | | Section 18.36 |
NS*| DELEGPURGE | OPT | FDELG (REQ) | Section 18.5 |
| DELEGRETURN | OPT | FDELG, | Section 18.6 |
| | | DDELG, pNFS | |
| | | (REQ) | |
NS | DESTROY_CLIENTID | REQ | | Section 18.50 |
I | DESTROY_SESSION | REQ | | Section 18.37 |
I | EXCHANGE_ID | REQ | | Section 18.35 |
NS | FREE_STATEID | REQ | | Section 18.38 |
| GETATTR | REQ | | Section 18.7 |
P | GETDEVICEINFO | OPT | pNFS (REQ) | Section 18.40 |
P | GETDEVICELIST | OPT | pNFS (OPT) | Section 18.41 |
| GETFH | REQ | | Section 18.8 |
NS*| GET_DIR_DELEGATION | OPT | DDELG (REQ) | Section 18.39 |
P | LAYOUTCOMMIT | OPT | pNFS (REQ) | Section 18.42 |
P | LAYOUTGET | OPT | pNFS (REQ) | Section 18.43 |
P | LAYOUTRETURN | OPT | pNFS (REQ) | Section 18.44 |
| LINK | OPT | | Section 18.9 |
| LOCK | REQ | | Section 18.10 |
| LOCKT | REQ | | Section 18.11 |
| LOCKU | REQ | | Section 18.12 |
| LOOKUP | REQ | | Section 18.13 |
| LOOKUPP | REQ | | Section 18.14 |
| NVERIFY | REQ | | Section 18.15 |
| OPEN | REQ | | Section 18.16 |
NS*| OPENATTR | OPT | | Section 18.17 |
| OPEN_CONFIRM | MNI | | N/A |
| OPEN_DOWNGRADE | REQ | | Section 18.18 |
| PUTFH | REQ | | Section 18.19 |
| PUTPUBFH | REQ | | Section 18.20 |
| PUTROOTFH | REQ | | Section 18.21 |
| READ | REQ | | Section 18.22 |
| READDIR | REQ | | Section 18.23 |
| READLINK | OPT | | Section 18.24 |
NS | RECLAIM_COMPLETE | REQ | | Section 18.51 |
| RELEASE_LOCKOWNER | MNI | | N/A |
| REMOVE | REQ | | Section 18.25 |
| RENAME | REQ | | Section 18.26 |
| RENEW | MNI | | N/A |
| RESTOREFH | REQ | | Section 18.27 |
| SAVEFH | REQ | | Section 18.28 |
| SECINFO | REQ | | Section 18.29 |
NS | SECINFO_NO_NAME | REC | pNFS files | Section 18.45, |
| | | layout (REQ) | Section 13.12 |
I | SEQUENCE | REQ | | Section 18.46 |
| SETATTR | REQ | | Section 18.30 |
| SETCLIENTID | MNI | | N/A |
| SETCLIENTID_CONFIRM | MNI | | N/A |
NS | SET_SSV | REQ | | Section 18.47 |
NS | TEST_STATEID | REQ | | Section 18.48 |
| VERIFY | REQ | | Section 18.31 |
NS*| WANT_DELEGATION | OPT | FDELG (OPT) | Section 18.49 |
| WRITE | REQ | | Section 18.32 |
Callback Operations
+-------------------------+-----------+-------------+---------------+
| Operation | REQ, REC, | Feature | Definition |
| | OPT, or | (REQ, REC, | |
| | MNI | or OPT) | |
+-------------------------+-----------+-------------+---------------+
| CB_GETATTR | OPT | FDELG (REQ) | Section 20.1 |
P | CB_LAYOUTRECALL | OPT | pNFS (REQ) | Section 20.3 |
NS*| CB_NOTIFY | OPT | DDELG (REQ) | Section 20.4 |
P | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | Section 20.12 |
NS*| CB_NOTIFY_LOCK | OPT | | Section 20.11 |
NS*| CB_PUSH_DELEG | OPT | FDELG (OPT) | Section 20.5 |
| CB_RECALL | OPT | FDELG, | Section 20.2 |
| | | DDELG, pNFS | |
| | | (REQ) | |
NS*| CB_RECALL_ANY | OPT | FDELG, | Section 20.6 |
| | | DDELG, pNFS | |
| | | (REQ) | |
NS | CB_RECALL_SLOT | REQ | | Section 20.8 |
NS*| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS | Section 20.7 |
| | | (REQ) | |
I | CB_SEQUENCE | OPT | FDELG, | Section 20.9 |
| | | DDELG, pNFS | |
| | | (REQ) | |
NS*| CB_WANTS_CANCELLED | OPT | FDELG, | Section 20.10 |
| | | DDELG, pNFS | |
| | | (REQ) | |
+-------------------------+-----------+-------------+---------------+
Implementation notes:
EXCHANGE_ID:
* only SP4_NONE state protection supported
* implementation ids are ignored
CREATE_SESSION:
* backchannel attributes are ignored
* backchannel security parameters are ignored
SEQUENCE:
* no support for dynamic slot table renegotiation (optional)
nfsv4.1 COMPOUND rules:
The following cases aren't supported yet:
* Enforcing of NFS4ERR_NOT_ONLY_OP for: BIND_CONN_TO_SESSION, CREATE_SESSION,
DESTROY_CLIENTID, DESTROY_SESSION, EXCHANGE_ID.
* DESTROY_SESSION MUST be the final operation in the COMPOUND request.

200
Documentation/filesystems/nilfs2.txt Normal file
View file

@ -0,0 +1,200 @@
NILFS2
------
NILFS2 is a log-structured file system (LFS) supporting continuous
snapshotting. In addition to versioning capability of the entire file
system, users can even restore files mistakenly overwritten or
destroyed just a few seconds ago. Since NILFS2 can keep consistency
like conventional LFS, it achieves quick recovery after system
crashes.
NILFS2 creates a number of checkpoints every few seconds or per
synchronous write basis (unless there is no change). Users can select
significant versions among continuously created checkpoints, and can
change them into snapshots which will be preserved until they are
changed back to checkpoints.
There is no limit on the number of snapshots until the volume gets
full. Each snapshot is mountable as a read-only file system
concurrently with its writable mount, and this feature is convenient
for online backup.
The userland tools are included in nilfs-utils package, which is
available from the following download page. At least "mkfs.nilfs2",
"mount.nilfs2", "umount.nilfs2", and "nilfs_cleanerd" (so called
cleaner or garbage collector) are required. Details on the tools are
described in the man pages included in the package.
Project web page: http://www.nilfs.org/en/
Download page: http://www.nilfs.org/en/download.html
Git tree web page: http://www.nilfs.org/git/
NILFS mailing lists: http://www.nilfs.org/mailman/listinfo/users
Caveats
=======
Features which NILFS2 does not support yet:
- atime
- extended attributes
- POSIX ACLs
- quotas
- writable snapshots
- remote backup (CDP)
- data integrity
- defragmentation
Mount options
=============
NILFS2 supports the following mount options:
(*) == default
barrier=on(*) This enables/disables barriers. barrier=off disables
it, barrier=on enables it.
errors=continue(*) Keep going on a filesystem error.
errors=remount-ro Remount the filesystem read-only on an error.
errors=panic Panic and halt the machine if an error occurs.
cp=n Specify the checkpoint-number of the snapshot to be
mounted. Checkpoints and snapshots are listed by lscp
user command. Only the checkpoints marked as snapshot
are mountable with this option. Snapshot is read-only,
so a read-only mount option must be specified together.
order=relaxed(*) Apply relaxed order semantics that allows modified data
blocks to be written to disk without making a
checkpoint if no metadata update is going. This mode
is equivalent to the ordered data mode of the ext3
filesystem except for the updates on data blocks still
conserve atomicity. This will improve synchronous
write performance for overwriting.
order=strict Apply strict in-order semantics that preserves sequence
of all file operations including overwriting of data
blocks. That means, it is guaranteed that no
overtaking of events occurs in the recovered file
system after a crash.
NILFS2 usage
============
To use nilfs2 as a local file system, simply:
# mkfs -t nilfs2 /dev/block_device
# mount -t nilfs2 /dev/block_device /dir
This will also invoke the cleaner through the mount helper program
(mount.nilfs2).
Checkpoints and snapshots are managed by the following commands.
Their manpages are included in the nilfs-utils package above.
lscp list checkpoints or snapshots.
mkcp make a checkpoint or a snapshot.
chcp change an existing checkpoint to a snapshot or vice versa.
rmcp invalidate specified checkpoint(s).
To mount a snapshot,
# mount -t nilfs2 -r -o cp=<cno> /dev/block_device /snap_dir
where <cno> is the checkpoint number of the snapshot.
To unmount the NILFS2 mount point or snapshot, simply:
# umount /dir
Then, the cleaner daemon is automatically shut down by the umount
helper program (umount.nilfs2).
Disk format
===========
A nilfs2 volume is equally divided into a number of segments except
for the super block (SB) and segment #0. A segment is the container
of logs. Each log is composed of summary information blocks, payload
blocks, and an optional super root block (SR):
______________________________________________________
| |SB| | Segment | Segment | Segment | ... | Segment | |
|_|__|_|____0____|____1____|____2____|_____|____N____|_|
0 +1K +4K +8M +16M +24M +(8MB x N)
. . (Typical offsets for 4KB-block)
. .
.______________________.
| log | log |... | log |
|__1__|__2__|____|__m__|
. .
. .
. .
.______________________________.
| Summary | Payload blocks |SR|
|_blocks__|_________________|__|
The payload blocks are organized per file, and each file consists of
data blocks and B-tree node blocks:
|<--- File-A --->|<--- File-B --->|
_______________________________________________________________
| Data blocks | B-tree blocks | Data blocks | B-tree blocks | ...
_|_____________|_______________|_____________|_______________|_
Since only the modified blocks are written in the log, it may have
files without data blocks or B-tree node blocks.
The organization of the blocks is recorded in the summary information
blocks, which contains a header structure (nilfs_segment_summary), per
file structures (nilfs_finfo), and per block structures (nilfs_binfo):
_________________________________________________________________________
| Summary | finfo | binfo | ... | binfo | finfo | binfo | ... | binfo |...
|_blocks__|___A___|_(A,1)_|_____|(A,Na)_|___B___|_(B,1)_|_____|(B,Nb)_|___
The logs include regular files, directory files, symbolic link files
and several meta data files. The mata data files are the files used
to maintain file system meta data. The current version of NILFS2 uses
the following meta data files:
1) Inode file (ifile) -- Stores on-disk inodes
2) Checkpoint file (cpfile) -- Stores checkpoints
3) Segment usage file (sufile) -- Stores allocation state of segments
4) Data address translation file -- Maps virtual block numbers to usual
(DAT) block numbers. This file serves to
make on-disk blocks relocatable.
The following figure shows a typical organization of the logs:
_________________________________________________________________________
| Summary | regular file | file | ... | ifile | cpfile | sufile | DAT |SR|
|_blocks__|_or_directory_|_______|_____|_______|________|________|_____|__|
To stride over segment boundaries, this sequence of files may be split
into multiple logs. The sequence of logs that should be treated as
logically one log, is delimited with flags marked in the segment
summary. The recovery code of nilfs2 looks this boundary information
to ensure atomicity of updates.
The super root block is inserted for every checkpoints. It includes
three special inodes, inodes for the DAT, cpfile, and sufile. Inodes
of regular files, directories, symlinks and other special files, are
included in the ifile. The inode of ifile itself is included in the
corresponding checkpoint entry in the cpfile. Thus, the hierarchy
among NILFS2 files can be depicted as follows:
Super block (SB)
|
v
Super root block (the latest cno=xx)
|-- DAT
|-- sufile
`-- cpfile
|-- ifile (cno=c1)
|-- ifile (cno=c2) ---- file (ino=i1)
: : |-- file (ino=i2)
`-- ifile (cno=xx) |-- file (ino=i3)
: :
`-- file (ino=yy)
( regular file, directory, or symlink )
For detail on the format of each file, please see include/linux/nilfs2_fs.h.

70
Documentation/filesystems/pohmelfs/design_notes.txt Normal file
View file

@ -0,0 +1,70 @@
POHMELFS: Parallel Optimized Host Message Exchange Layered File System.
Evgeniy Polyakov <zbr@ioremap.net>
Homepage: http://www.ioremap.net/projects/pohmelfs
POHMELFS first began as a network filesystem with coherent local data and
metadata caches but is now evolving into a parallel distributed filesystem.
Main features of this FS include:
* Locally coherent cache for data and metadata with (potentially) byte-range locks.
Since all Linux filesystems lock the whole inode during writing, algorithm
is very simple and does not use byte-ranges, although they are sent in
locking messages.
* Completely async processing of all events except creation of hard and symbolic
links, and rename events.
Object creation and data reading and writing are processed asynchronously.
* Flexible object architecture optimized for network processing.
Ability to create long paths to objects and remove arbitrarily huge
directories with a single network command.
(like removing the whole kernel tree via a single network command).
* Very high performance.
* Fast and scalable multithreaded userspace server. Being in userspace it works
with any underlying filesystem and still is much faster than async in-kernel NFS one.
* Client is able to switch between different servers (if one goes down, client
automatically reconnects to second and so on).
* Transactions support. Full failover for all operations.
Resending transactions to different servers on timeout or error.
* Read request (data read, directory listing, lookup requests) balancing between multiple servers.
* Write requests are replicated to multiple servers and completed only when all of them are acked.
* Ability to add and/or remove servers from the working set at run-time.
* Strong authentification and possible data encryption in network channel.
* Extended attributes support.
POHMELFS is based on transactions, which are potentially long-standing objects that live
in the client's memory. Each transaction contains all the information needed to process a given
command (or set of commands, which is frequently used during data writing: single transactions
can contain creation and data writing commands). Transactions are committed by all the servers
to which they are sent and, in case of failures, are eventually resent or dropped with an error.
For example, reading will return an error if no servers are available.
POHMELFS uses a asynchronous approach to data processing. Courtesy of transactions, it is
possible to detach replies from requests and, if the command requires data to be received, the
caller sleeps waiting for it. Thus, it is possible to issue multiple read commands to different
servers and async threads will pick up replies in parallel, find appropriate transactions in the
system and put the data where it belongs (like the page or inode cache).
The main feature of POHMELFS is writeback data and the metadata cache.
Only a few non-performance critical operations use the write-through cache and
are synchronous: hard and symbolic link creation, and object rename. Creation,
removal of objects and data writing are asynchronous and are sent to
the server during system writeback. Only one writer at a time is allowed for any
given inode, which is guarded by an appropriate locking protocol.
Because of this feature, POHMELFS is extremely fast at metadata intensive
workloads and can fully utilize the bandwidth to the servers when doing bulk
data transfers.
POHMELFS clients operate with a working set of servers and are capable of balancing read-only
operations (like lookups or directory listings) between them.
Administrators can add or remove servers from the set at run-time via special commands (described
in Documentation/pohmelfs/info.txt file). Writes are replicated to all servers.
POHMELFS is capable of full data channel encryption and/or strong crypto hashing.
One can select any kernel supported cipher, encryption mode, hash type and operation mode
(hmac or digest). It is also possible to use both or neither (default). Crypto configuration
is checked during mount time and, if the server does not support it, appropriate capabilities
will be disabled or mount will fail (if 'crypto_fail_unsupported' mount option is specified).
Crypto performance heavily depends on the number of crypto threads, which asynchronously perform
crypto operations and send the resulting data to server or submit it up the stack. This number
can be controlled via a mount option.

86
Documentation/filesystems/pohmelfs/info.txt Normal file
View file

@ -0,0 +1,86 @@
POHMELFS usage information.
Mount options:
idx=%u
Each mountpoint is associated with a special index via this option.
Administrator can add or remove servers from the given index, so all mounts,
which were attached to it, are updated.
Default it is 0.
trans_scan_timeout=%u
This timeout, expressed in milliseconds, specifies time to scan transaction
trees looking for stale requests, which have to be resent, or if number of
retries exceed specified limit, dropped with error.
Default is 5 seconds.
drop_scan_timeout=%u
Internal timeout, expressed in milliseconds, which specifies how frequently
inodes marked to be dropped are freed. It also specifies how frequently
the system checks that servers have to be added or removed from current working set.
Default is 1 second.
wait_on_page_timeout=%u
Number of milliseconds to wait for reply from remote server for data reading command.
If this timeout is exceeded, reading returns an error.
Default is 5 seconds.
trans_retries=%u
This is the number of times that a transaction will be resent to a server that did
not answer for the last @trans_scan_timeout milliseconds.
When the number of resends exceeds this limit, the transaction is completed with error.
Default is 5 resends.
crypto_thread_num=%u
Number of crypto processing threads. Threads are used both for RX and TX traffic.
Default is 2, or no threads if crypto operations are not supported.
trans_max_pages=%u
Maximum number of pages in a single transaction. This parameter also controls
the number of pages, allocated for crypto processing (each crypto thread has
pool of pages, the number of which is equal to 'trans_max_pages'.
Default is 100 pages.
crypto_fail_unsupported
If specified, mount will fail if the server does not support requested crypto operations.
By default mount will disable non-matching crypto operations.
mcache_timeout=%u
Maximum number of milliseconds to wait for the mcache objects to be processed.
Mcache includes locks (given lock should be granted by server), attributes (they should be
fully received in the given timeframe).
Default is 5 seconds.
Usage examples.
Add (or remove if it already exists) server server1.net:1025 into the working set with index $idx
with appropriate hash algorithm and key file and cipher algorithm, mode and key file:
$cfg -a server1.net -p 1025 -i $idx -K $hash_key -k $cipher_key
Mount filesystem with given index $idx to /mnt mountpoint.
Client will connect to all servers specified in the working set via previous command:
mount -t pohmel -o idx=$idx q /mnt
One can add or remove servers from working set after mounting too.
Server installation.
Creating a server, which listens at port 1025 and 0.0.0.0 address.
Working root directory (note, that server chroots there, so you have to have appropriate permissions)
is set to /mnt, server will negotiate hash/cipher with client, in case client requested it, there
are appropriate key files.
Number of working threads is set to 10.
# ./fserver -a 0.0.0.0 -p 1025 -r /mnt -w 10 -K hash_key -k cipher_key
-A 6 - listen on ipv6 address. Default: Disabled.
-r root - path to root directory. Default: /tmp.
-a addr - listen address. Default: 0.0.0.0.
-p port - listen port. Default: 1025.
-w workers - number of workers per connected client. Default: 1.
-K file - hash key size. Default: none.
-k file - cipher key size. Default: none.
-h - this help.
Number of worker threads specifies how many workers will be created for each client.
Bulk single-client transafers usually are better handled with smaller number (like 1-3).

227
Documentation/filesystems/pohmelfs/network_protocol.txt Normal file
View file

@ -0,0 +1,227 @@
POHMELFS network protocol.
Basic structure used in network communication is following command:
struct netfs_cmd
{
__u16 cmd; /* Command number */
__u16 csize; /* Attached crypto information size */
__u16 cpad; /* Attached padding size */
__u16 ext; /* External flags */
__u32 size; /* Size of the attached data */
__u32 trans; /* Transaction id */
__u64 id; /* Object ID to operate on. Used for feedback.*/
__u64 start; /* Start of the object. */
__u64 iv; /* IV sequence */
__u8 data[0];
};
Commands can be embedded into transaction command (which in turn has own command),
so one can extend protocol as needed without breaking backward compatibility as long
as old commands are supported. All string lengths include tail 0 byte.
All commans are transfered over the network in big-endian. CPU endianess is used at the end peers.
@cmd - command number, which specifies command to be processed. Following
commands are used currently:
NETFS_READDIR = 1, /* Read directory for given inode number */
NETFS_READ_PAGE, /* Read data page from the server */
NETFS_WRITE_PAGE, /* Write data page to the server */
NETFS_CREATE, /* Create directory entry */
NETFS_REMOVE, /* Remove directory entry */
NETFS_LOOKUP, /* Lookup single object */
NETFS_LINK, /* Create a link */
NETFS_TRANS, /* Transaction */
NETFS_OPEN, /* Open intent */
NETFS_INODE_INFO, /* Metadata cache coherency synchronization message */
NETFS_PAGE_CACHE, /* Page cache invalidation message */
NETFS_READ_PAGES, /* Read multiple contiguous pages in one go */
NETFS_RENAME, /* Rename object */
NETFS_CAPABILITIES, /* Capabilities of the client, for example supported crypto */
NETFS_LOCK, /* Distributed lock message */
NETFS_XATTR_SET, /* Set extended attribute */
NETFS_XATTR_GET, /* Get extended attribute */
@ext - external flags. Used by different commands to specify some extra arguments
like partial size of the embedded objects or creation flags.
@size - size of the attached data. For NETFS_READ_PAGE and NETFS_READ_PAGES no data is attached,
but size of the requested data is incorporated here. It does not include size of the command
header (struct netfs_cmd) itself.
@id - id of the object this command operates on. Each command can use it for own purpose.
@start - start of the object this command operates on. Each command can use it for own purpose.
@csize, @cpad - size and padding size of the (attached if needed) crypto information.
Command specifications.
@NETFS_READDIR
This command is used to sync content of the remote dir to the client.
@ext - length of the path to object.
@size - the same.
@id - local inode number of the directory to read.
@start - zero.
@NETFS_READ_PAGE
This command is used to read data from remote server.
Data size does not exceed local page cache size.
@id - inode number.
@start - first byte offset.
@size - number of bytes to read plus length of the path to object.
@ext - object path length.
@NETFS_CREATE
Used to create object.
It does not require that all directories on top of the object were
already created, it will create them automatically. Each object has
associated @netfs_path_entry data structure, which contains creation
mode (permissions and type) and length of the name as long as name itself.
@start - 0
@size - size of the all data structures needed to create a path
@id - local inode number
@ext - 0
@NETFS_REMOVE
Used to remove object.
@ext - length of the path to object.
@size - the same.
@id - local inode number.
@start - zero.
@NETFS_LOOKUP
Lookup information about object on server.
@ext - length of the path to object.
@size - the same.
@id - local inode number of the directory to look object in.
@start - local inode number of the object to look at.
@NETFS_LINK
Create hard of symlink.
Command is sent as "object_path|target_path".
@size - size of the above string.
@id - parent local inode number.
@start - 1 for symlink, 0 for hardlink.
@ext - size of the "object_path" above.
@NETFS_TRANS
Transaction header.
@size - incorporates all embedded command sizes including theirs header sizes.
@start - transaction generation number - unique id used to find transaction.
@ext - transaction flags. Unused at the moment.
@id - 0.
@NETFS_OPEN
Open intent for given transaction.
@id - local inode number.
@start - 0.
@size - path length to the object.
@ext - open flags (O_RDWR and so on).
@NETFS_INODE_INFO
Metadata update command.
It is sent to servers when attributes of the object are changed and received
when data or metadata were updated. It operates with the following structure:
struct netfs_inode_info
{
unsigned int mode;
unsigned int nlink;
unsigned int uid;
unsigned int gid;
unsigned int blocksize;
unsigned int padding;
__u64 ino;
__u64 blocks;
__u64 rdev;
__u64 size;
__u64 version;
};
It effectively mirrors stat(2) returned data.
@ext - path length to the object.
@size - the same plus size of the netfs_inode_info structure.
@id - local inode number.
@start - 0.
@NETFS_PAGE_CACHE
Command is only received by clients. It contains information about
page to be marked as not up-to-date.
@id - client's inode number.
@start - last byte of the page to be invalidated. If it is not equal to
current inode size, it will be vmtruncated().
@size - 0
@ext - 0
@NETFS_READ_PAGES
Used to read multiple contiguous pages in one go.
@start - first byte of the contiguous region to read.
@size - contains of two fields: lower 8 bits are used to represent page cache shift
used by client, another 3 bytes are used to get number of pages.
@id - local inode number.
@ext - path length to the object.
@NETFS_RENAME
Used to rename object.
Attached data is formed into following string: "old_path|new_path".
@id - local inode number.
@start - parent inode number.
@size - length of the above string.
@ext - length of the old path part.
@NETFS_CAPABILITIES
Used to exchange crypto capabilities with server.
If crypto capabilities are not supported by server, then client will disable it
or fail (if 'crypto_fail_unsupported' mount options was specified).
@id - superblock index. Used to specify crypto information for group of servers.
@size - size of the attached capabilities structure.
@start - 0.
@size - 0.
@scsize - 0.
@NETFS_LOCK
Used to send lock request/release messages. Although it sends byte range request
and is capable of flushing pages based on that, it is not used, since all Linux
filesystems lock the whole inode.
@id - lock generation number.
@start - start of the locked range.
@size - size of the locked range.
@ext - lock type: read/write. Not used actually. 15'th bit is used to determine,
if it is lock request (1) or release (0).
@NETFS_XATTR_SET
@NETFS_XATTR_GET
Used to set/get extended attributes for given inode.
@id - attribute generation number or xattr setting type
@start - size of the attribute (request or attached)
@size - name length, path len and data size for given attribute
@ext - path length for given object

1122
Documentation/filesystems/proc.txt
View file

File diff suppressed because it is too large Load diff

10
Documentation/filesystems/sysfs-pci.txt
View file

@ -12,6 +12,7 @@ that support it. For example, a given bus might look like this:
| |-- enable
| |-- irq
| |-- local_cpus
| |-- remove
| |-- resource
| |-- resource0
| |-- resource1
@ -36,6 +37,7 @@ files, each with their own function.
enable Whether the device is enabled (ascii, rw)
irq IRQ number (ascii, ro)
local_cpus nearby CPU mask (cpumask, ro)
remove remove device from kernel's list (ascii, wo)
resource PCI resource host addresses (ascii, ro)
resource0..N PCI resource N, if present (binary, mmap)
resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap)
@ -46,6 +48,7 @@ files, each with their own function.
ro - read only file
rw - file is readable and writable
wo - write only file
mmap - file is mmapable
ascii - file contains ascii text
binary - file contains binary data
@ -73,6 +76,13 @@ that the device must be enabled for a rom read to return data succesfully.
In the event a driver is not bound to the device, it can be enabled using the
'enable' file, documented above.
The 'remove' file is used to remove the PCI device, by writing a non-zero
integer to the file. This does not involve any kind of hot-plug functionality,
e.g. powering off the device. The device is removed from the kernel's list of
PCI devices, the sysfs directory for it is removed, and the device will be
removed from any drivers attached to it. Removal of PCI root buses is
disallowed.
Accessing legacy resources through sysfs
----------------------------------------

2
Documentation/filesystems/udf.txt
View file

@ -24,6 +24,8 @@ The following mount options are supported:
gid= Set the default group.
umask= Set the default umask.
mode= Set the default file permissions.
dmode= Set the default directory permissions.
uid= Set the default user.
bs= Set the block size.
unhide Show otherwise hidden files.

23
Documentation/gpio.txt
View file

@ -123,7 +123,10 @@ platform-specific implementation issue.
Using GPIOs
-----------
One of the first things to do with a GPIO, often in board setup code when
The first thing a system should do with a GPIO is allocate it, using
the gpio_request() call; see later.
One of the next things to do with a GPIO, often in board setup code when
setting up a platform_device using the GPIO, is mark its direction:
/* set as input or output, returning 0 or negative errno */
@ -141,8 +144,8 @@ This helps avoid signal glitching during system startup.
For compatibility with legacy interfaces to GPIOs, setting the direction
of a GPIO implicitly requests that GPIO (see below) if it has not been
requested already. That compatibility may be removed in the future;
explicitly requesting GPIOs is strongly preferred.
requested already. That compatibility is being removed from the optional
gpiolib framework.
Setting the direction can fail if the GPIO number is invalid, or when
that particular GPIO can't be used in that mode. It's generally a bad
@ -195,7 +198,7 @@ This requires sleeping, which can't be done from inside IRQ handlers.
Platforms that support this type of GPIO distinguish them from other GPIOs
by returning nonzero from this call (which requires a valid GPIO number,
either explicitly or implicitly requested):
which should have been previously allocated with gpio_request):
int gpio_cansleep(unsigned gpio);
@ -212,10 +215,9 @@ for GPIOs that can't be accessed from IRQ handlers, these calls act the
same as the spinlock-safe calls.
Claiming and Releasing GPIOs (OPTIONAL)
---------------------------------------
Claiming and Releasing GPIOs
----------------------------
To help catch system configuration errors, two calls are defined.
However, many platforms don't currently support this mechanism.
/* request GPIO, returning 0 or negative errno.
* non-null labels may be useful for diagnostics.
@ -244,13 +246,6 @@ Some platforms may also use knowledge about what GPIOs are active for
power management, such as by powering down unused chip sectors and, more
easily, gating off unused clocks.
These two calls are optional because not not all current Linux platforms
offer such functionality in their GPIO support; a valid implementation
could return success for all gpio_request() calls. Unlike the other calls,
the state they represent doesn't normally match anything from a hardware
register; it's just a software bitmap which clearly is not necessary for
correct operation of hardware or (bug free) drivers.
Note that requesting a GPIO does NOT cause it to be configured in any
way; it just marks that GPIO as in use. Separate code must handle any
pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown).

51
Documentation/hwmon/ds1621
View file

@ -49,12 +49,9 @@ of up to +/- 0.5 degrees even when compared against precise temperature
readings. Be sure to have a high vs. low temperature limit gap of al least
1.0 degree Celsius to avoid Tout "bouncing", though!
As for alarms, you can read the alarm status of the DS1621 via the 'alarms'
/sys file interface. The result consists mainly of bit 6 and 5 of the
configuration register of the chip; bit 6 (0x40 or 64) is the high alarm
bit and bit 5 (0x20 or 32) the low one. These bits are set when the high or
low limits are met or exceeded and are reset by the module as soon as the
respective temperature ranges are left.
The alarm bits are set when the high or low limits are met or exceeded and
are reset by the module as soon as the respective temperature ranges are
left.
The alarm registers are in no way suitable to find out about the actual
status of Tout. They will only tell you about its history, whether or not
@ -64,45 +61,3 @@ with neither of the alarms set.
Temperature conversion of the DS1621 takes up to 1000ms; internal access to
non-volatile registers may last for 10ms or below.
High Accuracy Temperature Reading
---------------------------------
As said before, the temperature issued via the 9-bit i2c-bus data is
somewhat arbitrary. Internally, the temperature conversion is of a
different kind that is explained (not so...) well in the DS1621 data sheet.
To cut the long story short: Inside the DS1621 there are two oscillators,
both of them biassed by a temperature coefficient.
Higher resolution of the temperature reading can be achieved using the
internal projection, which means taking account of REG_COUNT and REG_SLOPE
(the driver manages them):
Taken from Dallas Semiconductors App Note 068: 'Increasing Temperature
Resolution on the DS1620' and App Note 105: 'High Resolution Temperature
Measurement with Dallas Direct-to-Digital Temperature Sensors'
- Read the 9-bit temperature and strip the LSB (Truncate the .5 degs)
- The resulting value is TEMP_READ.
- Then, read REG_COUNT.
- And then, REG_SLOPE.
TEMP = TEMP_READ - 0.25 + ((REG_SLOPE - REG_COUNT) / REG_SLOPE)
Note that this is what the DONE bit in the DS1621 configuration register is
good for: Internally, one temperature conversion takes up to 1000ms. Before
that conversion is complete you will not be able to read valid things out
of REG_COUNT and REG_SLOPE. The DONE bit, as you may have guessed by now,
tells you whether the conversion is complete ("done", in plain English) and
thus, whether the values you read are good or not.
The DS1621 has two modes of operation: "Continuous" conversion, which can
be understood as the default stand-alone mode where the chip gets the
temperature and controls external devices via its Tout pin or tells other
i2c's about it if they care. The other mode is called "1SHOT", that means
that it only figures out about the temperature when it is explicitly told
to do so; this can be seen as power saving mode.
Now if you want to read REG_COUNT and REG_SLOPE, you have to either stop
the continuous conversions until the contents of these registers are valid,
or, in 1SHOT mode, you have to have one conversion made.

36
Documentation/hwmon/g760a Normal file
View file

@ -0,0 +1,36 @@
Kernel driver g760a
===================
Supported chips:
* Global Mixed-mode Technology Inc. G760A
Prefix: 'g760a'
Datasheet: Publicly available at the GMT website
http://www.gmt.com.tw/datasheet/g760a.pdf
Author: Herbert Valerio Riedel <hvr@gnu.org>
Description
-----------
The GMT G760A Fan Speed PWM Controller is connected directly to a fan
and performs closed-loop control of the fan speed.
The fan speed is programmed by setting the period via 'pwm1' of two
consecutive speed pulses. The period is defined in terms of clock
cycle counts of an assumed 32kHz clock source.
Setting a period of 0 stops the fan; setting the period to 255 sets
fan to maximum speed.
The measured fan rotation speed returned via 'fan1_input' is derived
from the measured speed pulse period by assuming again a 32kHz clock
source and a 2 pulse-per-revolution fan.
The 'alarms' file provides access to the two alarm bits provided by
the G760A chip's status register: Bit 0 is set when the actual fan
speed differs more than 20% with respect to the programmed fan speed;
bit 1 is set when fan speed is below 1920 RPM.
The g760a driver will not update its values more frequently than every
other second; reading them more often will do no harm, but will return
'old' values.

20
Documentation/hwmon/lis3lv02d
View file

@ -1,11 +1,11 @@
Kernel driver lis3lv02d
==================
=======================
Supported chips:
* STMicroelectronics LIS3LV02DL and LIS3LV02DQ
Author:
Authors:
Yan Burman <burman.yan@gmail.com>
Eric Piel <eric.piel@tremplin-utc.net>
@ -15,7 +15,7 @@ Description
This driver provides support for the accelerometer found in various HP
laptops sporting the feature officially called "HP Mobile Data
Protection System 3D" or "HP 3D DriveGuard". It detect automatically
Protection System 3D" or "HP 3D DriveGuard". It detects automatically
laptops with this sensor. Known models (for now the HP 2133, nc6420,
nc2510, nc8510, nc84x0, nw9440 and nx9420) will have their axis
automatically oriented on standard way (eg: you can directly play
@ -27,7 +27,7 @@ position - 3D position that the accelerometer reports. Format: "(x,y,z)"
calibrate - read: values (x, y, z) that are used as the base for input
class device operation.
write: forces the base to be recalibrated with the current
position.
position.
rate - reports the sampling rate of the accelerometer device in HZ
This driver also provides an absolute input class device, allowing
@ -48,7 +48,7 @@ For better compatibility between the various laptops. The values reported by
the accelerometer are converted into a "standard" organisation of the axes
(aka "can play neverball out of the box"):
* When the laptop is horizontal the position reported is about 0 for X and Y
and a positive value for Z
and a positive value for Z
* If the left side is elevated, X increases (becomes positive)
* If the front side (where the touchpad is) is elevated, Y decreases
(becomes negative)
@ -59,3 +59,13 @@ email to the authors to add it to the database. When reporting a new
laptop, please include the output of "dmidecode" plus the value of
/sys/devices/platform/lis3lv02d/position in these four cases.
Q&A
---
Q: How do I safely simulate freefall? I have an HP "portable
workstation" which has about 3.5kg and a plastic case, so letting it
fall to the ground is out of question...
A: The sensor is pretty sensitive, so your hands can do it. Lift it
into free space, follow the fall with your hands for like 10
centimeters. That should be enough to trigger the detection.

50
Documentation/hwmon/ltc4215 Normal file
View file

@ -0,0 +1,50 @@
Kernel driver ltc4215
=====================
Supported chips:
* Linear Technology LTC4215
Prefix: 'ltc4215'
Addresses scanned: 0x44
Datasheet:
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
Author: Ira W. Snyder <iws@ovro.caltech.edu>
Description
-----------
The LTC4215 controller allows a board to be safely inserted and removed
from a live backplane.
Usage Notes
-----------
This driver does not probe for LTC4215 devices, due to the fact that some
of the possible addresses are unfriendly to probing. You will need to use
the "force" parameter to tell the driver where to find the device.
Example: the following will load the driver for an LTC4215 at address 0x44
on I2C bus #0:
$ modprobe ltc4215 force=0,0x44
Sysfs entries
-------------
The LTC4215 has built-in limits for overvoltage, undervoltage, and
undercurrent warnings. This makes it very likely that the reference
circuit will be used.
in1_input input voltage
in2_input output voltage
in1_min_alarm input undervoltage alarm
in1_max_alarm input overvoltage alarm
curr1_input current
curr1_max_alarm overcurrent alarm
power1_input power usage
power1_alarm power bad alarm

0
Documentation/i2c/chips/pcf8591 → Documentation/hwmon/pcf8591
View file

22
Documentation/hwmon/sysfs-interface
View file

@ -365,6 +365,7 @@ energy[1-*]_input Cumulative energy use
Unit: microJoule
RO
**********
* Alarms *
**********
@ -453,6 +454,27 @@ beep_mask Bitmask for beep.
RW
***********************
* Intrusion detection *
***********************
intrusion[0-*]_alarm
Chassis intrusion detection
0: OK
1: intrusion detected
RW
Contrary to regular alarm flags which clear themselves
automatically when read, this one sticks until cleared by
the user. This is done by writing 0 to the file. Writing
other values is unsupported.
intrusion[0-*]_beep
Chassis intrusion beep
0: disable
1: enable
RW
sysfs attribute writes interpretation
-------------------------------------

29
Documentation/hwmon/w83627ehf
View file

@ -2,30 +2,40 @@ Kernel driver w83627ehf
=======================
Supported chips:
* Winbond W83627EHF/EHG/DHG (ISA access ONLY)
* Winbond W83627EHF/EHG (ISA access ONLY)
Prefix: 'w83627ehf'
Addresses scanned: ISA address retrieved from Super I/O registers
Datasheet:
http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83627EHF_%20W83627EHGb.pdf
DHG datasheet confidential.
http://www.nuvoton.com.tw/NR/rdonlyres/A6A258F0-F0C9-4F97-81C0-C4D29E7E943E/0/W83627EHF.pdf
* Winbond W83627DHG
Prefix: 'w83627dhg'
Addresses scanned: ISA address retrieved from Super I/O registers
Datasheet:
http://www.nuvoton.com.tw/NR/rdonlyres/7885623D-A487-4CF9-A47F-30C5F73D6FE6/0/W83627DHG.pdf
* Winbond W83667HG
Prefix: 'w83667hg'
Addresses scanned: ISA address retrieved from Super I/O registers
Datasheet: not available
Authors:
Jean Delvare <khali@linux-fr.org>
Yuan Mu (Winbond)
Rudolf Marek <r.marek@assembler.cz>
David Hubbard <david.c.hubbard@gmail.com>
Gong Jun <JGong@nuvoton.com>
Description
-----------
This driver implements support for the Winbond W83627EHF, W83627EHG, and
W83627DHG super I/O chips. We will refer to them collectively as Winbond chips.
This driver implements support for the Winbond W83627EHF, W83627EHG,
W83627DHG and W83667HG super I/O chips. We will refer to them collectively
as Winbond chips.
The chips implement three temperature sensors, five fan rotation
speed sensors, ten analog voltage sensors (only nine for the 627DHG), one
VID (6 pins for the 627EHF/EHG, 8 pins for the 627DHG), alarms with beep
warnings (control unimplemented), and some automatic fan regulation
strategies (plus manual fan control mode).
VID (6 pins for the 627EHF/EHG, 8 pins for the 627DHG and 667HG), alarms
with beep warnings (control unimplemented), and some automatic fan
regulation strategies (plus manual fan control mode).
Temperatures are measured in degrees Celsius and measurement resolution is 1
degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
@ -54,7 +64,8 @@ follows:
temp1 -> pwm1
temp2 -> pwm2
temp3 -> pwm3
prog -> pwm4 (the programmable setting is not supported by the driver)
prog -> pwm4 (not on 667HG; the programmable setting is not supported by
the driver)
/sys files
----------

2
Documentation/ia64/kvm.txt
View file

@ -42,7 +42,7 @@ Note: For step 2, please make sure that host page size == TARGET_PAGE_SIZE of qe
hg clone http://xenbits.xensource.com/ext/efi-vfirmware.hg
you can get the firmware's binary in the directory of efi-vfirmware.hg/binaries.
(3) Rename the firware you owned to Flash.fd, and copy it to /usr/local/share/qemu
(3) Rename the firmware you owned to Flash.fd, and copy it to /usr/local/share/qemu
4. Boot up Linux or Windows guests:
4.1 Create or install a image for guest boot. If you have xen experience, it should be easy.

45
Documentation/infiniband/ipoib.txt
View file

@ -24,6 +24,49 @@ Partitions and P_Keys
The P_Key for any interface is given by the "pkey" file, and the
main interface for a subinterface is in "parent."
Datagram vs Connected modes
The IPoIB driver supports two modes of operation: datagram and
connected. The mode is set and read through an interface's
/sys/class/net/<intf name>/mode file.
In datagram mode, the IB UD (Unreliable Datagram) transport is used
and so the interface MTU has is equal to the IB L2 MTU minus the
IPoIB encapsulation header (4 bytes). For example, in a typical IB
fabric with a 2K MTU, the IPoIB MTU will be 2048 - 4 = 2044 bytes.
In connected mode, the IB RC (Reliable Connected) transport is used.
Connected mode is to takes advantage of the connected nature of the
IB transport and allows an MTU up to the maximal IP packet size of
64K, which reduces the number of IP packets needed for handling
large UDP datagrams, TCP segments, etc and increases the performance
for large messages.
In connected mode, the interface's UD QP is still used for multicast
and communication with peers that don't support connected mode. In
this case, RX emulation of ICMP PMTU packets is used to cause the
networking stack to use the smaller UD MTU for these neighbours.
Stateless offloads
If the IB HW supports IPoIB stateless offloads, IPoIB advertises
TCP/IP checksum and/or Large Send (LSO) offloading capability to the
network stack.
Large Receive (LRO) offloading is also implemented and may be turned
on/off using ethtool calls. Currently LRO is supported only for
checksum offload capable devices.
Stateless offloads are supported only in datagram mode.
Interrupt moderation
If the underlying IB device supports CQ event moderation, one can
use ethtool to set interrupt mitigation parameters and thus reduce
the overhead incurred by handling interrupts. The main code path of
IPoIB doesn't use events for TX completion signaling so only RX
moderation is supported.
Debugging Information
By compiling the IPoIB driver with CONFIG_INFINIBAND_IPOIB_DEBUG set
@ -55,3 +98,5 @@ References
http://ietf.org/rfc/rfc4391.txt
IP over InfiniBand (IPoIB) Architecture (RFC 4392)
http://ietf.org/rfc/rfc4392.txt
IP over InfiniBand: Connected Mode (RFC 4755)
http://ietf.org/rfc/rfc4755.txt

101
Documentation/input/rotary-encoder.txt Normal file
View file

@ -0,0 +1,101 @@
rotary-encoder - a generic driver for GPIO connected devices
Daniel Mack <daniel@caiaq.de>, Feb 2009
0. Function
-----------
Rotary encoders are devices which are connected to the CPU or other
peripherals with two wires. The outputs are phase-shifted by 90 degrees
and by triggering on falling and rising edges, the turn direction can
be determined.
The phase diagram of these two outputs look like this:
_____ _____ _____
| | | | | |
Channel A ____| |_____| |_____| |____
: : : : : : : : : : : :
__ _____ _____ _____
| | | | | | |
Channel B |_____| |_____| |_____| |__
: : : : : : : : : : : :
Event a b c d a b c d a b c d
|<-------->|
one step
For more information, please see
http://en.wikipedia.org/wiki/Rotary_encoder
1. Events / state machine
-------------------------
a) Rising edge on channel A, channel B in low state
This state is used to recognize a clockwise turn
b) Rising edge on channel B, channel A in high state
When entering this state, the encoder is put into 'armed' state,
meaning that there it has seen half the way of a one-step transition.
c) Falling edge on channel A, channel B in high state
This state is used to recognize a counter-clockwise turn
d) Falling edge on channel B, channel A in low state
Parking position. If the encoder enters this state, a full transition
should have happend, unless it flipped back on half the way. The
'armed' state tells us about that.
2. Platform requirements
------------------------
As there is no hardware dependent call in this driver, the platform it is
used with must support gpiolib. Another requirement is that IRQs must be
able to fire on both edges.
3. Board integration
--------------------
To use this driver in your system, register a platform_device with the
name 'rotary-encoder' and associate the IRQs and some specific platform
data with it.
struct rotary_encoder_platform_data is declared in
include/linux/rotary-encoder.h and needs to be filled with the number of
steps the encoder has and can carry information about externally inverted
signals (because of used invertig buffer or other reasons).
Because GPIO to IRQ mapping is platform specific, this information must
be given in seperately to the driver. See the example below.
---------<snip>---------
/* board support file example */
#include <linux/input.h>
#include <linux/rotary_encoder.h>
#define GPIO_ROTARY_A 1
#define GPIO_ROTARY_B 2
static struct rotary_encoder_platform_data my_rotary_encoder_info = {
.steps = 24,
.axis = ABS_X,
.gpio_a = GPIO_ROTARY_A,
.gpio_b = GPIO_ROTARY_B,
.inverted_a = 0,
.inverted_b = 0,
};
static struct platform_device rotary_encoder_device = {
.name = "rotary-encoder",
.id = 0,
.dev = {
.platform_data = &my_rotary_encoder_info,
}
};

52
Documentation/isdn/README.gigaset
View file

@ -61,24 +61,28 @@ GigaSet 307x Device Driver
---------------------
2.1. Modules
-------
To get the device working, you have to load the proper kernel module. You
can do this using
modprobe modulename
where modulename is ser_gigaset (M101), usb_gigaset (M105), or
bas_gigaset (direct USB connection to the base).
For the devices to work, the proper kernel modules have to be loaded.
This normally happens automatically when the system detects the USB
device (base, M105) or when the line discipline is attached (M101). It
can also be triggered manually using the modprobe(8) command, for example
for troubleshooting or to pass module parameters.
The module ser_gigaset provides a serial line discipline N_GIGASET_M101
which drives the device through the regular serial line driver. To use it,
run the Gigaset M101 daemon "gigasetm101d" (also available from
http://sourceforge.net/projects/gigaset307x/) with the device file of the
RS232 port to the M101 as an argument, for example:
gigasetm101d /dev/ttyS1
This will open the device file, set its line discipline to N_GIGASET_M101,
and then sleep in the background, keeping the device open so that the
line discipline remains active. To deactivate it, kill the daemon, for
example with
killall gigasetm101d
before disconnecting the device.
which drives the device through the regular serial line driver. It must
be attached to the serial line to which the M101 is connected with the
ldattach(8) command (requires util-linux-ng release 2.14 or later), for
example:
ldattach GIGASET_M101 /dev/ttyS1
This will open the device file, attach the line discipline to it, and
then sleep in the background, keeping the device open so that the line
discipline remains active. To deactivate it, kill the daemon, for example
with
killall ldattach
before disconnecting the device. To have this happen automatically at
system startup/shutdown on an LSB compatible system, create and activate
an appropriate LSB startup script /etc/init.d/gigaset. (The init name
'gigaset' is officially assigned to this project by LANANA.)
Alternatively, just add the 'ldattach' command line to /etc/rc.local.
2.2. Device nodes for user space programs
------------------------------------
@ -194,10 +198,11 @@ GigaSet 307x Device Driver
operation (for wireless access to the base), but are needed for access
to the M105's own configuration mode (registration to the base, baudrate
and line format settings, device status queries) via the gigacontr
utility. Their use is disabled in the driver by default for safety
reasons but can be enabled by setting the kernel configuration option
"Support for undocumented USB requests" (GIGASET_UNDOCREQ) to "Y" and
recompiling.
utility. Their use is controlled by the kernel configuration option
"Support for undocumented USB requests" (CONFIG_GIGASET_UNDOCREQ). If you
encounter error code -ENOTTY when trying to use some features of the
M105, try setting that option to "y" via 'make {x,menu}config' and
recompiling the driver.
3. Troubleshooting
@ -228,6 +233,13 @@ GigaSet 307x Device Driver
Solution:
Select Unimodem mode for all DECT data adapters. (see section 2.4.)
Problem:
You want to configure your USB DECT data adapter (M105) but gigacontr
reports an error: "/dev/ttyGU0: Inappropriate ioctl for device".
Solution:
Recompile the usb_gigaset driver with the kernel configuration option
CONFIG_GIGASET_UNDOCREQ set to 'y'. (see section 2.6.)
3.2. Telling the driver to provide more information
----------------------------------------------
Building the driver with the "Gigaset debugging" kernel configuration

83
Documentation/kbuild/makefiles.txt
View file

@ -40,10 +40,16 @@ This document describes the Linux kernel Makefiles.
--- 6.7 Custom kbuild commands
--- 6.8 Preprocessing linker scripts
=== 7 Kbuild Variables
=== 8 Makefile language
=== 9 Credits
=== 10 TODO
=== 7 Kbuild syntax for exported headers
--- 7.1 header-y
--- 7.2 objhdr-y
--- 7.3 destination-y
--- 7.4 unifdef-y (deprecated)
=== 8 Kbuild Variables
=== 9 Makefile language
=== 10 Credits
=== 11 TODO
=== 1 Overview
@ -1143,8 +1149,69 @@ When kbuild executes, the following steps are followed (roughly):
The kbuild infrastructure for *lds file are used in several
architecture-specific files.
=== 7 Kbuild syntax for exported headers
=== 7 Kbuild Variables
The kernel include a set of headers that is exported to userspace.
Many headers can be exported as-is but other headers requires a
minimal pre-processing before they are ready for user-space.
The pre-processing does:
- drop kernel specific annotations
- drop include of compiler.h
- drop all sections that is kernel internat (guarded by ifdef __KERNEL__)
Each relevant directory contain a file name "Kbuild" which specify the
headers to be exported.
See subsequent chapter for the syntax of the Kbuild file.
--- 7.1 header-y
header-y specify header files to be exported.
Example:
#include/linux/Kbuild
header-y += usb/
header-y += aio_abi.h
The convention is to list one file per line and
preferably in alphabetic order.
header-y also specify which subdirectories to visit.
A subdirectory is identified by a trailing '/' which
can be seen in the example above for the usb subdirectory.
Subdirectories are visited before their parent directories.
--- 7.2 objhdr-y
objhdr-y specifies generated files to be exported.
Generated files are special as they need to be looked
up in another directory when doing 'make O=...' builds.
Example:
#include/linux/Kbuild
objhdr-y += version.h
--- 7.3 destination-y
When an architecture have a set of exported headers that needs to be
exported to a different directory destination-y is used.
destination-y specify the destination directory for all exported
headers in the file where it is present.
Example:
#arch/xtensa/platforms/s6105/include/platform/Kbuild
destination-y := include/linux
In the example above all exported headers in the Kbuild file
will be located in the directory "include/linux" when exported.
--- 7.4 unifdef-y (deprecated)
unifdef-y is deprecated. A direct replacement is header-y.
=== 8 Kbuild Variables
The top Makefile exports the following variables:
@ -1206,7 +1273,7 @@ The top Makefile exports the following variables:
INSTALL_MOD_STRIP will used as the option(s) to the strip command.
=== 8 Makefile language
=== 9 Makefile language
The kernel Makefiles are designed to be run with GNU Make. The Makefiles
use only the documented features of GNU Make, but they do use many
@ -1225,14 +1292,14 @@ time the left-hand side is used.
There are some cases where "=" is appropriate. Usually, though, ":="
is the right choice.
=== 9 Credits
=== 10 Credits
Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
Updates by Sam Ravnborg <sam@ravnborg.org>
Language QA by Jan Engelhardt <jengelh@gmx.de>
=== 10 TODO
=== 11 TODO
- Describe how kbuild supports shipped files with _shipped.
- Generating offset header files.

527
Documentation/kernel-parameters.txt
View file

@ -50,6 +50,7 @@ parameter is applicable:
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
KMEMTRACE kmemtrace is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
LOOP Loopback device support is enabled.
@ -152,60 +153,6 @@ and is between 256 and 4096 characters. It is defined in the file
1,0: use 1st APIC table
default: 0
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
old_ordering, s4_nonvs }
See Documentation/power/video.txt for information on
s3_bios and s3_mode.
s3_beep is for debugging; it makes the PC's speaker beep
as soon as the kernel's real-mode entry point is called.
s4_nohwsig prevents ACPI hardware signature from being
used during resume from hibernation.
old_ordering causes the ACPI 1.0 ordering of the _PTS
control method, with respect to putting devices into
low power states, to be enforced (the ACPI 2.0 ordering
of _PTS is used by default).
s4_nonvs prevents the kernel from saving/restoring the
ACPI NVS memory during hibernation.
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Format: { level | edge | high | low }
acpi_irq_balance [HW,ACPI]
ACPI will balance active IRQs
default in APIC mode
acpi_irq_nobalance [HW,ACPI]
ACPI will not move active IRQs (default)
default in PIC mode
acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
use by PCI
Format: <irq>,<irq>...
acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Format: <irq>,<irq>...
acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
Format: To spoof as Windows 98: ="Microsoft Windows"
acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
acpi_osi="string1" # add string1 -- only one string
acpi_osi="!string2" # remove built-in string2
acpi_osi= # disable all strings
acpi_serialize [HW,ACPI] force serialization of AML methods
acpi_skip_timer_override [HW,ACPI]
Recognize and ignore IRQ0/pin2 Interrupt Override.
For broken nForce2 BIOS resulting in XT-PIC timer.
acpi_use_timer_override [HW,ACPI]
Use timer override. For some broken Nvidia NF5 boards
that require a timer override, but don't have
HPET
acpi_backlight= [HW,ACPI]
acpi_backlight=vendor
acpi_backlight=video
@ -213,11 +160,6 @@ and is between 256 and 4096 characters. It is defined in the file
(e.g. thinkpad_acpi, sony_acpi, etc.) instead
of the ACPI video.ko driver.
acpi_display_output= [HW,ACPI]
acpi_display_output=vendor
acpi_display_output=video
See above.
acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
Format: <int>
@ -246,6 +188,41 @@ and is between 256 and 4096 characters. It is defined in the file
unusable. The "log_buf_len" parameter may be useful
if you need to capture more output.
acpi_display_output= [HW,ACPI]
acpi_display_output=vendor
acpi_display_output=video
See above.
acpi_irq_balance [HW,ACPI]
ACPI will balance active IRQs
default in APIC mode
acpi_irq_nobalance [HW,ACPI]
ACPI will not move active IRQs (default)
default in PIC mode
acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Format: <irq>,<irq>...
acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
use by PCI
Format: <irq>,<irq>...
acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
Format: To spoof as Windows 98: ="Microsoft Windows"
acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
acpi_osi="string1" # add string1 -- only one string
acpi_osi="!string2" # remove built-in string2
acpi_osi= # disable all strings
acpi_pm_good [X86-32,X86-64]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value
and always returns good values.
acpi.power_nocheck= [HW,ACPI]
Format: 1/0 enable/disable the check of power state.
On some bogus BIOS the _PSC object/_STA object of
@ -254,26 +231,21 @@ and is between 256 and 4096 characters. It is defined in the file
power state again in power transition.
1 : disable the power state check
acpi_pm_good [X86-32,X86-64]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value
and always returns good values.
agp= [AGP]
{ off | try_unsupported }
off: disable AGP support
try_unsupported: try to drive unsupported chipsets
(may crash computer or cause data corruption)
enable_timer_pin_1 [i386,x86-64]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
(in particular on some ATI chipsets).
The kernel tries to set a reasonable default.
disable_timer_pin_1 [i386,x86-64]
Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs.
acpi_enforce_resources= [ACPI]
{ strict | lax | no }
Check for resource conflicts between native drivers
and ACPI OperationRegions (SystemIO and SystemMemory
only). IO ports and memory declared in ACPI might be
used by the ACPI subsystem in arbitrary AML code and
can interfere with legacy drivers.
strict (default): access to resources claimed by ACPI
is denied; legacy drivers trying to access reserved
resources will fail to bind to device using them.
lax: access to resources claimed by ACPI is allowed;
legacy drivers trying to access reserved resources
will bind successfully but a warning message is logged.
no: ACPI OperationRegions are not marked as reserved,
no further checks are performed.
ad1848= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<type>
@ -288,6 +260,12 @@ and is between 256 and 4096 characters. It is defined in the file
Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
See also header of sound/oss/aedsp16.c.
agp= [AGP]
{ off | try_unsupported }
off: disable AGP support
try_unsupported: try to drive unsupported chipsets
(may crash computer or cause data corruption)
aha152x= [HW,SCSI]
See Documentation/scsi/aha152x.txt.
@ -415,12 +393,6 @@ and is between 256 and 4096 characters. It is defined in the file
possible to determine what the correct size should be.
This option provides an override for these situations.
security= [SECURITY] Choose a security module to enable at boot.
If this boot parameter is not specified, only the first
security module asking for security registration will be
loaded. An invalid security module name will be treated
as if no module has been chosen.
capability.disable=
[SECURITY] Disable capabilities. This would normally
be used only if an alternative security model is to be
@ -492,24 +464,6 @@ and is between 256 and 4096 characters. It is defined in the file
Range: 0 - 8192
Default: 64
dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
this option disables the debugging code at boot.
dma_debug_entries=<number>
This option allows to tune the number of preallocated
entries for DMA-API debugging code. One entry is
required per DMA-API allocation. Use this if the
DMA-API debugging code disables itself because the
architectural default is too low.
hpet= [X86-32,HPET] option to control HPET usage
Format: { enable (default) | disable | force |
verbose }
disable: disable HPET and use PIT instead
force: allow force enabled of undocumented chips (ICH4,
VIA, nVidia)
verbose: show contents of HPET registers during setup
com20020= [HW,NET] ARCnet - COM20020 chipset
Format:
<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
@ -553,23 +507,6 @@ and is between 256 and 4096 characters. It is defined in the file
console=brl,ttyS0
For now, only VisioBraille is supported.
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
The options are the same as for ttyS, above.
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
hibernate operations. Once disabled, debugging
messages can reach various consoles while the rest
of the system is being put to sleep (ie, while
debugging driver suspend/resume hooks). This may
not work reliably with all consoles, but is known
to work with serial and VGA consoles.
coredump_filter=
[KNL] Change the default value for
/proc/<pid>/coredump_filter.
@ -617,36 +554,22 @@ and is between 256 and 4096 characters. It is defined in the file
debug_objects [KNL] Enable object debugging
no_debug_objects
[KNL] Disable object debugging
debugpat [X86] Enable PAT debugging
decnet.addr= [HW,NET]
Format: <area>[,<node>]
See also Documentation/networking/decnet.txt.
vt.default_blu= [VT]
Format: <blue0>,<blue1>,<blue2>,...,<blue15>
Change the default blue palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_grn= [VT]
Format: <green0>,<green1>,<green2>,...,<green15>
Change the default green palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_red= [VT]
Format: <red0>,<red1>,<red2>,...,<red15>
Change the default red palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_utf8=
[VT]
Format=<0|1>
Set system-wide default UTF-8 mode for all tty's.
Default is 1, i.e. UTF-8 mode is enabled for all
newly opened terminals.
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
@ -659,27 +582,9 @@ and is between 256 and 4096 characters. It is defined in the file
Documentation/serial/digiepca.txt.
disable_mtrr_cleanup [X86]
enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB
entry later. This parameter enables/disables that.
mtrr_chunk_size=nn[KMG] [X86]
used for mtrr cleanup. It is largest continous chunk
that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86]
Used for mtrr cleanup. It is granularity of mtrr block.
Default is 1.
Large value could prevent small alignment from
using up MTRRs.
mtrr_spare_reg_nr=n [X86]
Format: <integer>
Range: 0,7 : spare reg number
Default : 1
Used for mtrr cleanup. It is spare mtrr entries number.
Set to 2 or more if your graphical card needs more.
entry later. This parameter disables that.
disable_mtrr_trim [X86, Intel and AMD only]
By default the kernel will trim any uncacheable
@ -687,12 +592,38 @@ and is between 256 and 4096 characters. It is defined in the file
MTRR settings. This parameter disables that behavior,
possibly causing your machine to run very slowly.
disable_timer_pin_1 [i386,x86-64]
Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs.
dmasound= [HW,OSS] Sound subsystem buffers
dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
this option disables the debugging code at boot.
dma_debug_entries=<number>
This option allows to tune the number of preallocated
entries for DMA-API debugging code. One entry is
required per DMA-API allocation. Use this if the
DMA-API debugging code disables itself because the
architectural default is too low.
dscc4.setup= [NET]
dtc3181e= [HW,SCSI]
dynamic_printk Enables pr_debug()/dev_dbg() calls if
CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
These can also be switched on/off via
<debugfs>/dynamic_printk/modules
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
The options are the same as for ttyS, above.
earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]
@ -734,6 +665,17 @@ and is between 256 and 4096 characters. It is defined in the file
pass this option to capture kernel.
See Documentation/kdump/kdump.txt for details.
enable_mtrr_cleanup [X86]
The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB
entry later. This parameter enables that.
enable_timer_pin_1 [i386,x86-64]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
(in particular on some ATI chipsets).
The kernel tries to set a reasonable default.
enforcing [SELINUX] Set initial enforcing status.
Format: {"0" | "1"}
See security/selinux/Kconfig help text.
@ -821,6 +763,16 @@ and is between 256 and 4096 characters. It is defined in the file
hisax= [HW,ISDN]
See Documentation/isdn/README.HiSax.
hlt [BUGS=ARM,SH]
hpet= [X86-32,HPET] option to control HPET usage
Format: { enable (default) | disable | force |
verbose }
disable: disable HPET and use PIT instead
force: allow force enabled of undocumented chips (ICH4,
VIA, nVidia)
verbose: show contents of HPET registers during setup
hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
On x86-64 and powerpc, this option can be specified
@ -830,15 +782,6 @@ and is between 256 and 4096 characters. It is defined in the file
(when the CPU supports the "pdpe1gb" cpuinfo flag)
Note that 1GB pages can only be allocated at boot time
using hugepages= and not freed afterwards.
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
hlt [BUGS=ARM,SH]
hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
terminal devices. Valid values: 0..8
@ -899,6 +842,9 @@ and is between 256 and 4096 characters. It is defined in the file
idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
See Documentation/ide/ide.txt.
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
Claim all unknown PCI IDE storage controllers.
idle= [X86]
Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly
@ -914,9 +860,6 @@ and is between 256 and 4096 characters. It is defined in the file
In such case C2/C3 won't be used again.
idle=nomwait: Disable mwait for CPU C-states
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
Claim all unknown PCI IDE storage controllers.
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
@ -950,25 +893,6 @@ and is between 256 and 4096 characters. It is defined in the file
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
inttest= [IA64]
iomem= Disable strict checking of access to MMIO memory
strict regions from userspace.
relaxed
iommu= [x86]
off
force
noforce
biomerge
panic
nopanic
merge
nomerge
forcesac
soft
intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
on
Enable intel iommu driver.
@ -992,6 +916,28 @@ and is between 256 and 4096 characters. It is defined in the file
result in a hardware IOTLB flush operation as opposed
to batching them for performance.
inttest= [IA64]
iomem= Disable strict checking of access to MMIO memory
strict regions from userspace.
relaxed
iommu= [x86]
off
force
noforce
biomerge
panic
nopanic
merge
nomerge
forcesac
soft
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
io_delay= [X86-32,X86-64] I/O delay method
0x80
Standard port 0x80 based delay
@ -1002,10 +948,6 @@ and is between 256 and 4096 characters. It is defined in the file
none
No delay
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
ip= [IP_PNP]
See Documentation/filesystems/nfsroot.txt.
@ -1016,12 +958,6 @@ and is between 256 and 4096 characters. It is defined in the file
ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
See header of drivers/scsi/ips.c.
ports= [IP_VS_FTP] IPVS ftp helper module
Default is 21.
Up to 8 (IP_VS_APP_MAX_PORTS) ports
may be specified.
Format: <port>,<port>....
irqfixup [HW]
When an interrupt is not handled search all handlers
for it. Intended to get systems with badly broken
@ -1062,6 +998,8 @@ and is between 256 and 4096 characters. It is defined in the file
js= [HW,JOY] Analog joystick
See Documentation/input/joystick.txt.
keepinitrd [HW,ARM]
kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
specifies the amount of memory usable by the kernel
for non-movable allocations. The requested amount is
@ -1078,20 +1016,14 @@ and is between 256 and 4096 characters. It is defined in the file
use the HighMem zone if it exists, and the Normal
zone if it does not.
movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
is similar to kernelcore except it specifies the
amount of memory used for migratable allocations.
If both kernelcore and movablecore is specified,
then kernelcore will be at *least* the specified
value but may be more. If movablecore on its own
is specified, the administrator must be careful
that the amount of memory usable for all allocations
is not too small.
kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
Controls whether kmemtrace is enabled
at boot-time.
keepinitrd [HW,ARM]
kstack=N [X86-32,X86-64] Print N words from the kernel stack
in oops dumps.
kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
subbufs kmemtrace's relay channel has. Set this
higher than default (KMEMTRACE_N_SUBBUFS in code) if
you experience buffer overruns.
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
@ -1102,6 +1034,9 @@ and is between 256 and 4096 characters. It is defined in the file
Configure the RouterBoard 532 series on-chip
Ethernet adapter MAC address.
kstack=N [X86-32,X86-64] Print N words from the kernel stack
in oops dumps.
l2cr= [PPC]
l3cr= [PPC]
@ -1247,9 +1182,8 @@ and is between 256 and 4096 characters. It is defined in the file
(machvec) in a generic kernel.
Example: machvec=hpzx1_swiotlb
max_loop= [LOOP] Maximum number of loopback devices that can
be mounted
Format: <1-256>
max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
than or equal to this physical address is ignored.
maxcpus= [SMP] Maximum number of processors that an SMP kernel
should make use of. maxcpus=n : n >= 0 limits the
@ -1257,8 +1191,9 @@ and is between 256 and 4096 characters. It is defined in the file
it is equivalent to "nosmp", which also disables
the IO APIC.
max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
or equal to this physical address is ignored.
max_loop= [LOOP] Maximum number of loopback devices that can
be mounted
Format: <1-256>
max_luns= [SCSI] Maximum number of LUNs to probe.
Should be between 1 and 2^32-1.
@ -1385,6 +1320,16 @@ and is between 256 and 4096 characters. It is defined in the file
mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
reporting absolute coordinates, such as tablets
movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
is similar to kernelcore except it specifies the
amount of memory used for migratable allocations.
If both kernelcore and movablecore is specified,
then kernelcore will be at *least* the specified
value but may be more. If movablecore on its own
is specified, the administrator must be careful
that the amount of memory usable for all allocations
is not too small.
mpu401= [HW,OSS]
Format: <io>,<irq>
@ -1406,6 +1351,23 @@ and is between 256 and 4096 characters. It is defined in the file
[HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n')
mtrr_chunk_size=nn[KMG] [X86]
used for mtrr cleanup. It is largest continous chunk
that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86]
Used for mtrr cleanup. It is granularity of mtrr block.
Default is 1.
Large value could prevent small alignment from
using up MTRRs.
mtrr_spare_reg_nr=n [X86]
Format: <integer>
Range: 0,7 : spare reg number
Default : 1
Used for mtrr cleanup. It is spare mtrr entries number.
Set to 2 or more if your graphical card needs more.
n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
NCR_D700= [HW,SCSI]
@ -1466,11 +1428,13 @@ and is between 256 and 4096 characters. It is defined in the file
0 - turn nmi_watchdog off
1 - use the IO-APIC timer for the NMI watchdog
2 - use the local APIC for the NMI watchdog using
a performance counter. Note: This will use one performance
counter and the local APIC's performance vector.
When panic is specified panic when an NMI watchdog timeout occurs.
This is useful when you use a panic=... timeout and need the box
quickly up again.
a performance counter. Note: This will use one
performance counter and the local APIC's performance
vector.
When panic is specified, panic when an NMI watchdog
timeout occurs.
This is useful when you use a panic=... timeout and
need the box quickly up again.
Instead of 1 and 2 it is possible to use the following
symbolic names: lapic and ioapic
Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
@ -1479,6 +1443,16 @@ and is between 256 and 4096 characters. It is defined in the file
emulation library even if a 387 maths coprocessor
is present.
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
hibernate operations. Once disabled, debugging
messages can reach various consoles while the rest
of the system is being put to sleep (ie, while
debugging driver suspend/resume hooks). This may
not work reliably with all consoles, but is known
to work with serial and VGA consoles.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
caches in the slab allocator. Saves per-node memory,
but will impact performance.
@ -1493,6 +1467,8 @@ and is between 256 and 4096 characters. It is defined in the file
nocache [ARM]
noclflush [BUGS=X86] Don't use the CLFLUSH instruction
nodelayacct [KNL] Disable per-task delay accounting
nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
@ -1521,9 +1497,9 @@ and is between 256 and 4096 characters. It is defined in the file
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
noclflush [BUGS=X86] Don't use the CLFLUSH instruction
nohlt [BUGS=ARM,SH]
nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
no-hlt [BUGS=X86-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
@ -1544,6 +1520,8 @@ and is between 256 and 4096 characters. It is defined in the file
Valid arguments: on, off
Default: on
noiotrap [SH] Disables trapped I/O port accesses.
noirqdebug [X86-32] Disables the code which attempts to detect and
disable unhandled interrupt sources.
@ -1563,12 +1541,6 @@ and is between 256 and 4096 characters. It is defined in the file
nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
nox2apic [X86-64,APIC] Do not enable x2APIC mode.
x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
default x2apic cluster mode on platforms
supporting x2apic.
noltlbs [PPC] Do not use large page/tlb entries for kernel
lowmem mapping on PPC40x.
@ -1579,6 +1551,9 @@ and is between 256 and 4096 characters. It is defined in the file
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
@ -1603,7 +1578,7 @@ and is between 256 and 4096 characters. It is defined in the file
nosoftlockup [KNL] Disable the soft-lockup detector.
noswapaccount [KNL] Disable accounting of swap in memory resource
controller. (See Documentation/controllers/memory.txt)
controller. (See Documentation/cgroups/memory.txt)
nosync [HW,M68K] Disables sync negotiation for all devices.
@ -1617,13 +1592,13 @@ and is between 256 and 4096 characters. It is defined in the file
purges which is reported from either PAL_VM_SUMMARY or
SAL PALO.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
one of ['zone', 'node', 'default'] can be specified
This can be set from sysctl after boot.
See Documentation/sysctl/vm.txt for details.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
See Documentation/debugging-via-ohci1394.txt for more
info.
@ -1695,6 +1670,8 @@ and is between 256 and 4096 characters. It is defined in the file
See also Documentation/blockdev/paride.txt.
pci=option[,option...] [PCI] various PCI subsystem options:
earlydump [X86] dump PCI config space before the kernel
changes anything
off [X86] don't probe for the PCI bus
bios [X86-32] force use of PCI BIOS, don't access
the hardware directly. Use this if your machine
@ -1794,6 +1771,15 @@ and is between 256 and 4096 characters. It is defined in the file
cbmemsize=nn[KMG] The fixed amount of bus space which is
reserved for the CardBus bridge's memory
window. The default value is 64 megabytes.
resource_alignment=
Format:
[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
Specifies alignment and device to reassign
aligned memory resources.
If <order of align> is not specified,
PAGE_SIZE is used as alignment.
PCI-PCI bridge can be specified, if resource
windows need to be expanded.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
@ -1861,6 +1847,14 @@ and is between 256 and 4096 characters. It is defined in the file
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)
processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
max_cstate=9 overrides any DMI blacklist limit.
processor.nocst [HW,ACPI]
Ignore the _CST method to determine C-states,
instead using the legacy FADT method
profile= [KNL] Enable kernel profiling via /proc/profile
Format: [schedule,]<number>
Param: "schedule" - profile schedule points.
@ -1870,14 +1864,6 @@ and is between 256 and 4096 characters. It is defined in the file
Requires CONFIG_SCHEDSTATS
Param: "kvm" - profile VM exits.
processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
max_cstate=9 overrides any DMI blacklist limit.
processor.nocst [HW,ACPI]
Ignore the _CST method to determine C-states,
instead using the legacy FADT method
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading.
See Documentation/blockdev/ramdisk.txt.
@ -1942,7 +1928,7 @@ and is between 256 and 4096 characters. It is defined in the file
relax_domain_level=
[KNL, SMP] Set scheduler's default relax_domain_level.
See Documentation/cpusets.txt.
See Documentation/cgroups/cpusets.txt.
reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
@ -2031,7 +2017,13 @@ and is between 256 and 4096 characters. It is defined in the file
allowing boot to proceed. none ignores them, expecting
user space to do the scan.
selinux [SELINUX] Disable or enable SELinux at boot time.
security= [SECURITY] Choose a security module to enable at boot.
If this boot parameter is not specified, only the first
security module asking for security registration will be
loaded. An invalid security module name will be treated
as if no module has been chosen.
selinux= [SELINUX] Disable or enable SELinux at boot time.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
0 -- disable.
@ -2351,6 +2343,8 @@ and is between 256 and 4096 characters. It is defined in the file
tp720= [HW,PS2]
trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
trix= [HW,OSS] MediaTrix AudioTrix Pro
Format:
<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
@ -2453,9 +2447,6 @@ and is between 256 and 4096 characters. It is defined in the file
medium is write-protected).
Example: quirks=0419:aaf5:rl,0421:0433:rc
add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
kernel's map of available physical RAM.
vdso= [X86-32,SH,x86-64]
vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)
@ -2494,6 +2485,31 @@ and is between 256 and 4096 characters. It is defined in the file
vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command>
vt.default_blu= [VT]
Format: <blue0>,<blue1>,<blue2>,...,<blue15>
Change the default blue palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_grn= [VT]
Format: <green0>,<green1>,<green2>,...,<green15>
Change the default green palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_red= [VT]
Format: <red0>,<red1>,<red2>,...,<red15>
Change the default red palette of the console.
This is a 16-member array composed of values
ranging from 0-255.
vt.default_utf8=
[VT]
Format=<0|1>
Set system-wide default UTF-8 mode for all tty's.
Default is 1, i.e. UTF-8 mode is enabled for all
newly opened terminals.
waveartist= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
@ -2506,6 +2522,10 @@ and is between 256 and 4096 characters. It is defined in the file
wdt= [WDT] Watchdog
See Documentation/watchdog/wdt.txt.
x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
default x2apic cluster mode on platforms
supporting x2apic.
xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
xd_geo= See header of drivers/block/xd.c.
@ -2513,9 +2533,6 @@ and is between 256 and 4096 characters. It is defined in the file
Format:
<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
______________________________________________________________________
TODO:

38
Documentation/kprobes.txt
View file

@ -212,7 +212,9 @@ hit, Kprobes calls kp->pre_handler. After the probed instruction
is single-stepped, Kprobe calls kp->post_handler. If a fault
occurs during execution of kp->pre_handler or kp->post_handler,
or during single-stepping of the probed instruction, Kprobes calls
kp->fault_handler. Any or all handlers can be NULL.
kp->fault_handler. Any or all handlers can be NULL. If kp->flags
is set KPROBE_FLAG_DISABLED, that kp will be registered but disabled,
so, it's handlers aren't hit until calling enable_kprobe(kp).
NOTE:
1. With the introduction of the "symbol_name" field to struct kprobe,
@ -363,6 +365,26 @@ probes) in the specified array, they clear the addr field of those
incorrect probes. However, other probes in the array are
unregistered correctly.
4.7 disable_*probe
#include <linux/kprobes.h>
int disable_kprobe(struct kprobe *kp);
int disable_kretprobe(struct kretprobe *rp);
int disable_jprobe(struct jprobe *jp);
Temporarily disables the specified *probe. You can enable it again by using
enable_*probe(). You must specify the probe which has been registered.
4.8 enable_*probe
#include <linux/kprobes.h>
int enable_kprobe(struct kprobe *kp);
int enable_kretprobe(struct kretprobe *rp);
int enable_jprobe(struct jprobe *jp);
Enables *probe which has been disabled by disable_*probe(). You must specify
the probe which has been registered.
5. Kprobes Features and Limitations
Kprobes allows multiple probes at the same address. Currently,
@ -500,10 +522,14 @@ the probe. If the probed function belongs to a module, the module name
is also specified. Following columns show probe status. If the probe is on
a virtual address that is no longer valid (module init sections, module
virtual addresses that correspond to modules that've been unloaded),
such probes are marked with [GONE].
such probes are marked with [GONE]. If the probe is temporarily disabled,
such probes are marked with [DISABLED].
/debug/kprobes/enabled: Turn kprobes ON/OFF
/debug/kprobes/enabled: Turn kprobes ON/OFF forcibly.
Provides a knob to globally turn registered kprobes ON or OFF. By default,
all kprobes are enabled. By echoing "0" to this file, all registered probes
will be disarmed, till such time a "1" is echoed to this file.
Provides a knob to globally and forcibly turn registered kprobes ON or OFF.
By default, all kprobes are enabled. By echoing "0" to this file, all
registered probes will be disarmed, till such time a "1" is echoed to this
file. Note that this knob just disarms and arms all kprobes and doesn't
change each probe's disabling state. This means that disabled kprobes (marked
[DISABLED]) will be not enabled if you turn ON all kprobes by this knob.

10
Documentation/laptops/acer-wmi.txt
View file

@ -1,9 +1,9 @@
Acer Laptop WMI Extras Driver
http://code.google.com/p/aceracpi
Version 0.2
18th August 2008
Version 0.3
4th April 2009
Copyright 2007-2008 Carlos Corbacho <carlos@strangeworlds.co.uk>
Copyright 2007-2009 Carlos Corbacho <carlos@strangeworlds.co.uk>
acer-wmi is a driver to allow you to control various parts of your Acer laptop
hardware under Linux which are exposed via ACPI-WMI.
@ -36,6 +36,10 @@ not possible in kernel space from a 64 bit OS.
Supported Hardware
******************
NOTE: The Acer Aspire One is not supported hardware. It cannot work with
acer-wmi until Acer fix their ACPI-WMI implementation on them, so has been
blacklisted until that happens.
Please see the website for the current list of known working hardare:
http://code.google.com/p/aceracpi/wiki/SupportedHardware

144
Documentation/laptops/thinkpad-acpi.txt
View file

@ -20,7 +20,8 @@ moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
kernel 2.6.29 and release 0.22.
The driver is named "thinkpad-acpi". In some places, like module
names, "thinkpad_acpi" is used because of userspace issues.
names and log messages, "thinkpad_acpi" is used because of userspace
issues.
"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
long due to length limitations on some Linux kernel versions.
@ -37,7 +38,7 @@ detailed description):
- ThinkLight on and off
- limited docking and undocking
- UltraBay eject
- CMOS control
- CMOS/UCMS control
- LED control
- ACPI sounds
- temperature sensors
@ -46,6 +47,7 @@ detailed description):
- Volume control
- Fan control and monitoring: fan speed, fan enable/disable
- WAN enable and disable
- UWB enable and disable
A compatibility table by model and feature is maintained on the web
site, http://ibm-acpi.sf.net/. I appreciate any success or failure
@ -53,7 +55,7 @@ reports, especially if they add to or correct the compatibility table.
Please include the following information in your report:
- ThinkPad model name
- a copy of your DSDT, from /proc/acpi/dsdt
- a copy of your ACPI tables, using the "acpidump" utility
- a copy of the output of dmidecode, with serial numbers
and UUIDs masked off
- which driver features work and which don't
@ -66,17 +68,18 @@ Installation
------------
If you are compiling this driver as included in the Linux kernel
sources, simply enable the CONFIG_THINKPAD_ACPI option, and optionally
enable the CONFIG_THINKPAD_ACPI_BAY option if you want the
thinkpad-specific bay functionality.
sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
It is located on the menu path: "Device Drivers" -> "X86 Platform
Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
Features
--------
The driver exports two different interfaces to userspace, which can be
used to access the features it provides. One is a legacy procfs-based
interface, which will be removed at some time in the distant future.
The other is a new sysfs-based interface which is not complete yet.
interface, which will be removed at some time in the future. The other
is a new sysfs-based interface which is not complete yet.
The procfs interface creates the /proc/acpi/ibm directory. There is a
file under that directory for each feature it supports. The procfs
@ -111,15 +114,17 @@ The version of thinkpad-acpi's sysfs interface is exported by the driver
as a driver attribute (see below).
Sysfs driver attributes are on the driver's sysfs attribute space,
for 2.6.23 this is /sys/bus/platform/drivers/thinkpad_acpi/ and
for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
/sys/bus/platform/drivers/thinkpad_hwmon/
Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
space, for 2.6.23 this is /sys/devices/platform/thinkpad_acpi/.
space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
Sysfs device attributes for the sensors and fan are on the
thinkpad_hwmon device's sysfs attribute space, but you should locate it
looking for a hwmon device with the name attribute of "thinkpad".
looking for a hwmon device with the name attribute of "thinkpad", or
better yet, through libsensors.
Driver version
--------------
@ -129,6 +134,7 @@ sysfs driver attribute: version
The driver name and version. No commands can be written to this file.
Sysfs interface version
-----------------------
@ -160,6 +166,7 @@ expect that an attribute might not be there, and deal with it properly
(an attribute not being there *is* a valid way to make it clear that a
feature is not available in sysfs).
Hot keys
--------
@ -172,17 +179,14 @@ system. Enabling the hotkey functionality of thinkpad-acpi signals the
firmware that such a driver is present, and modifies how the ThinkPad
firmware will behave in many situations.
The driver enables the hot key feature automatically when loaded. The
feature can later be disabled and enabled back at runtime. The driver
will also restore the hot key feature to its previous state and mask
when it is unloaded.
The driver enables the HKEY ("hot key") event reporting automatically
when loaded, and disables it when it is removed.
When the hotkey feature is enabled and the hot key mask is set (see
below), the driver will report HKEY events in the following format:
The driver will report HKEY events in the following format:
ibm/hotkey HKEY 00000080 0000xxxx
Some of these events refer to hot key presses, but not all.
Some of these events refer to hot key presses, but not all of them.
The driver will generate events over the input layer for hot keys and
radio switches, and over the ACPI netlink layer for other events. The
@ -214,13 +218,17 @@ procfs notes:
The following commands can be written to the /proc/acpi/ibm/hotkey file:
echo enable > /proc/acpi/ibm/hotkey -- enable the hot keys feature
echo disable > /proc/acpi/ibm/hotkey -- disable the hot keys feature
echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
... any other 8-hex-digit mask ...
echo reset > /proc/acpi/ibm/hotkey -- restore the original mask
The following commands have been deprecated and will cause the kernel
to log a warning:
echo enable > /proc/acpi/ibm/hotkey -- does nothing
echo disable > /proc/acpi/ibm/hotkey -- returns an error
The procfs interface does not support NVRAM polling control. So as to
maintain maximum bug-to-bug compatibility, it does not report any masks,
nor does it allow one to manipulate the hot key mask when the firmware
@ -229,12 +237,9 @@ does not support masks at all, even if NVRAM polling is in use.
sysfs notes:
hotkey_bios_enabled:
Returns the status of the hot keys feature when
thinkpad-acpi was loaded. Upon module unload, the hot
key feature status will be restored to this value.
DEPRECATED, WILL BE REMOVED SOON.
0: hot keys were disabled
1: hot keys were enabled (unusual)
Returns 0.
hotkey_bios_mask:
Returns the hot keys mask when thinkpad-acpi was loaded.
@ -242,13 +247,10 @@ sysfs notes:
to this value.
hotkey_enable:
Enables/disables the hot keys feature in the ACPI
firmware, and reports current status of the hot keys
feature. Has no effect on the NVRAM hot key polling
functionality.
DEPRECATED, WILL BE REMOVED SOON.
0: disables the hot keys feature / feature disabled
1: enables the hot keys feature / feature enabled
0: returns -EPERM
1: does nothing
hotkey_mask:
bit mask to enable driver-handling (and depending on
@ -618,6 +620,7 @@ For Lenovo models *with* ACPI backlight control:
and map them to KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN. Process
these keys on userspace somehow (e.g. by calling xbacklight).
Bluetooth
---------
@ -628,6 +631,9 @@ sysfs rfkill class: switch "tpacpi_bluetooth_sw"
This feature shows the presence and current state of a ThinkPad
Bluetooth device in the internal ThinkPad CDC slot.
If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
so it is kept across reboots and power-off.
Procfs notes:
If Bluetooth is installed, the following commands can be used:
@ -652,6 +658,7 @@ Sysfs notes:
rfkill controller switch "tpacpi_bluetooth_sw": refer to
Documentation/rfkill.txt for details.
Video output control -- /proc/acpi/ibm/video
--------------------------------------------
@ -693,11 +700,8 @@ Fn-F7 from working. This also disables the video output switching
features of this driver, as it uses the same ACPI methods as
Fn-F7. Video switching on the console should still work.
UPDATE: There's now a patch for the X.org Radeon driver which
addresses this issue. Some people are reporting success with the patch
while others are still having problems. For more information:
UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
https://bugs.freedesktop.org/show_bug.cgi?id=2000
ThinkLight control
------------------
@ -720,10 +724,11 @@ The ThinkLight sysfs interface is documented by the LED class
documentation, in Documentation/leds-class.txt. The ThinkLight LED name
is "tpacpi::thinklight".
Due to limitations in the sysfs LED class, if the status of the thinklight
Due to limitations in the sysfs LED class, if the status of the ThinkLight
cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
It is impossible to know if the status returned through sysfs is valid.
Docking / undocking -- /proc/acpi/ibm/dock
------------------------------------------
@ -784,6 +789,7 @@ the only docking stations currently supported are the X-series
UltraBase docks and "dumb" port replicators like the Mini Dock (the
latter don't need any ACPI support, actually).
UltraBay eject -- /proc/acpi/ibm/bay
------------------------------------
@ -847,8 +853,9 @@ supported. Use "eject2" instead of "eject" for the second bay.
Note: the UltraBay eject support on the 600e/x, A22p and A3x is
EXPERIMENTAL and may not work as expected. USE WITH CAUTION!
CMOS control
------------
CMOS/UCMS control
-----------------
procfs: /proc/acpi/ibm/cmos
sysfs device attribute: cmos_command
@ -882,6 +889,7 @@ The cmos command interface is prone to firmware split-brain problems, as
in newer ThinkPads it is just a compatibility layer. Do not use it, it is
exported just as a debug tool.
LED control
-----------
@ -893,6 +901,17 @@ some older ThinkPad models, it is possible to query the status of the
LED indicators as well. Newer ThinkPads cannot query the real status
of the LED indicators.
Because misuse of the LEDs could induce an unaware user to perform
dangerous actions (like undocking or ejecting a bay device while the
buses are still active), or mask an important alarm (such as a nearly
empty battery, or a broken battery), access to most LEDs is
restricted.
Unrestricted access to all LEDs requires that thinkpad-acpi be
compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
Distributions must never enable this option. Individual users that
are aware of the consequences are welcome to enabling it.
procfs notes:
The available commands are:
@ -939,6 +958,7 @@ ThinkPad indicator LED should blink in hardware accelerated mode, use the
"timer" trigger, and leave the delay_on and delay_off parameters set to
zero (to request hardware acceleration autodetection).
ACPI sounds -- /proc/acpi/ibm/beep
----------------------------------
@ -968,6 +988,7 @@ X40:
16 - one medium-pitched beep repeating constantly, stop with 17
17 - stop 16
Temperature sensors
-------------------
@ -1115,6 +1136,7 @@ registers contain the current battery capacity, etc. If you experiment
with this, do send me your results (including some complete dumps with
a description of the conditions when they were taken.)
LCD brightness control
----------------------
@ -1124,10 +1146,9 @@ sysfs backlight device "thinkpad_screen"
This feature allows software control of the LCD brightness on ThinkPad
models which don't have a hardware brightness slider.
It has some limitations: the LCD backlight cannot be actually turned on or
off by this interface, and in many ThinkPad models, the "dim while on
battery" functionality will be enabled by the BIOS when this interface is
used, and cannot be controlled.
It has some limitations: the LCD backlight cannot be actually turned
on or off by this interface, it just controls the backlight brightness
level.
On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
has eight brightness levels, ranging from 0 to 7. Some of the levels
@ -1136,10 +1157,15 @@ display backlight brightness control methods have 16 levels, ranging
from 0 to 15.
There are two interfaces to the firmware for direct brightness control,
EC and CMOS. To select which one should be used, use the
EC and UCMS (or CMOS). To select which one should be used, use the
brightness_mode module parameter: brightness_mode=1 selects EC mode,
brightness_mode=2 selects CMOS mode, brightness_mode=3 selects both EC
and CMOS. The driver tries to auto-detect which interface to use.
brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
mode with NVRAM backing (so that brightness changes are remembered
across shutdown/reboot).
The driver tries to select which interface to use from a table of
defaults for each ThinkPad model. If it makes a wrong choice, please
report this as a bug, so that we can fix it.
When display backlight brightness controls are available through the
standard ACPI interface, it is best to use it instead of this direct
@ -1201,6 +1227,7 @@ WARNING:
and maybe reduce the life of the backlight lamps by needlessly kicking
its level up and down at every change.
Volume control -- /proc/acpi/ibm/volume
---------------------------------------
@ -1217,6 +1244,11 @@ distinct. The unmute the volume after the mute command, use either the
up or down command (the level command will not unmute the volume).
The current volume level and mute state is shown in the file.
The ALSA mixer interface to this feature is still missing, but patches
to add it exist. That problem should be addressed in the not so
distant future.
Fan control and monitoring: fan speed, fan enable/disable
---------------------------------------------------------
@ -1383,8 +1415,11 @@ procfs: /proc/acpi/ibm/wan
sysfs device attribute: wwan_enable (deprecated)
sysfs rfkill class: switch "tpacpi_wwan_sw"
This feature shows the presence and current state of a W-WAN (Sierra
Wireless EV-DO) device.
This feature shows the presence and current state of the built-in
Wireless WAN device.
If the ThinkPad supports it, the WWAN state is stored in NVRAM,
so it is kept across reboots and power-off.
It was tested on a Lenovo ThinkPad X60. It should probably work on other
ThinkPad models which come with this module installed.
@ -1413,6 +1448,7 @@ Sysfs notes:
rfkill controller switch "tpacpi_wwan_sw": refer to
Documentation/rfkill.txt for details.
EXPERIMENTAL: UWB
-----------------
@ -1431,6 +1467,7 @@ Sysfs notes:
rfkill controller switch "tpacpi_uwb_sw": refer to
Documentation/rfkill.txt for details.
Multiple Commands, Module Parameters
------------------------------------
@ -1445,6 +1482,7 @@ for example:
modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
Enabling debugging output
-------------------------
@ -1457,8 +1495,15 @@ will enable all debugging output classes. It takes a bitmask, so
to enable more than one output class, just add their values.
Debug bitmask Description
0x8000 Disclose PID of userspace programs
accessing some functions of the driver
0x0001 Initialization and probing
0x0002 Removal
0x0004 RF Transmitter control (RFKILL)
(bluetooth, WWAN, UWB...)
0x0008 HKEY event interface, hotkeys
0x0010 Fan control
0x0020 Backlight brightness
There is also a kernel build option to enable more debugging
information, which may be necessary to debug driver problems.
@ -1467,6 +1512,7 @@ The level of debugging information output by the driver can be changed
at runtime through sysfs, using the driver attribute debug_level. The
attribute takes the same bitmask as the debug module parameter above.
Force loading of module
-----------------------
@ -1505,3 +1551,7 @@ Sysfs interface changelog:
0x020200: Add poll()/select() support to the following attributes:
hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
0x020300: hotkey enable/disable support removed, attributes
hotkey_bios_enabled and hotkey_enable deprecated and
marked for removal.

7
Documentation/lguest/lguest.c
View file

@ -1630,6 +1630,13 @@ static bool service_io(struct device *dev)
}
}
/* OK, so we noted that it was pretty poor to use an fdatasync as a
* barrier. But Christoph Hellwig points out that we need a sync
* *afterwards* as well: "Barriers specify no reordering to the front
* or the back." And Jens Axboe confirmed it, so here we are: */
if (out->type & VIRTIO_BLK_T_BARRIER)
fdatasync(vblk->fd);
/* We can't trigger an IRQ, because we're not the Launcher. It does
* that when we tell it we're done. */
add_used(dev->vq, head, wlen);

30
Documentation/lockdep-design.txt
View file

@ -27,33 +27,37 @@ lock-class.
State
-----
The validator tracks lock-class usage history into 5 separate state bits:
The validator tracks lock-class usage history into 4n + 1 separate state bits:
- 'ever held in hardirq context' [ == hardirq-safe ]
- 'ever held in softirq context' [ == softirq-safe ]
- 'ever held with hardirqs enabled' [ == hardirq-unsafe ]
- 'ever held with softirqs and hardirqs enabled' [ == softirq-unsafe ]
- 'ever held in STATE context'
- 'ever head as readlock in STATE context'
- 'ever head with STATE enabled'
- 'ever head as readlock with STATE enabled'
Where STATE can be either one of (kernel/lockdep_states.h)
- hardirq
- softirq
- reclaim_fs
- 'ever used' [ == !unused ]
When locking rules are violated, these 4 state bits are presented in the
locking error messages, inside curlies. A contrived example:
When locking rules are violated, these state bits are presented in the
locking error messages, inside curlies. A contrived example:
modprobe/2287 is trying to acquire lock:
(&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
(&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24
but task is already holding lock:
(&sio_locks[i].lock){--..}, at: [<c02867fd>] mutex_lock+0x21/0x24
(&sio_locks[i].lock){-.-...}, at: [<c02867fd>] mutex_lock+0x21/0x24
The bit position indicates hardirq, softirq, hardirq-read,
softirq-read respectively, and the character displayed in each
indicates:
The bit position indicates STATE, STATE-read, for each of the states listed
above, and the character displayed in each indicates:
'.' acquired while irqs disabled
'+' acquired in irq context
'-' acquired with irqs enabled
'?' read acquired in irq context with irqs enabled.
'?' acquired in irq context with irqs enabled.
Unused mutexes cannot be part of the cause of an error.

37
Documentation/md.txt
View file

@ -164,15 +164,19 @@ All md devices contain:
raid_disks
a text file with a simple number indicating the number of devices
in a fully functional array. If this is not yet known, the file
will be empty. If an array is being resized (not currently
possible) this will contain the larger of the old and new sizes.
Some raid level (RAID1) allow this value to be set while the
array is active. This will reconfigure the array. Otherwise
it can only be set while assembling an array.
will be empty. If an array is being resized this will contain
the new number of devices.
Some raid levels allow this value to be set while the array is
active. This will reconfigure the array. Otherwise it can only
be set while assembling an array.
A change to this attribute will not be permitted if it would
reduce the size of the array. To reduce the number of drives
in an e.g. raid5, the array size must first be reduced by
setting the 'array_size' attribute.
chunk_size
This is the size if bytes for 'chunks' and is only relevant to
raid levels that involve striping (1,4,5,6,10). The address space
This is the size in bytes for 'chunks' and is only relevant to
raid levels that involve striping (0,4,5,6,10). The address space
of the array is conceptually divided into chunks and consecutive
chunks are striped onto neighbouring devices.
The size should be at least PAGE_SIZE (4k) and should be a power
@ -183,6 +187,20 @@ All md devices contain:
simply a number that is interpretted differently by different
levels. It can be written while assembling an array.
array_size
This can be used to artificially constrain the available space in
the array to be less than is actually available on the combined
devices. Writing a number (in Kilobytes) which is less than
the available size will set the size. Any reconfiguration of the
array (e.g. adding devices) will not cause the size to change.
Writing the word 'default' will cause the effective size of the
array to be whatever size is actually available based on
'level', 'chunk_size' and 'component_size'.
This can be used to reduce the size of the array before reducing
the number of devices in a raid4/5/6, or to support external
metadata formats which mandate such clipping.
reshape_position
This is either "none" or a sector number within the devices of
the array where "reshape" is up to. If this is set, the three
@ -207,6 +225,11 @@ All md devices contain:
about the array. It can be 0.90 (traditional format), 1.0, 1.1,
1.2 (newer format in varying locations) or "none" indicating that
the kernel isn't managing metadata at all.
Alternately it can be "external:" followed by a string which
is set by user-space. This indicates that metadata is managed
by a user-space program. Any device failure or other event that
requires a metadata update will cause array activity to be
suspended until the event is acknowledged.
resync_start
The point at which resync should start. If no resync is needed,

62
Documentation/misc-devices/isl29003 Normal file
View file

@ -0,0 +1,62 @@
Kernel driver isl29003
=====================
Supported chips:
* Intersil ISL29003
Prefix: 'isl29003'
Addresses scanned: none
Datasheet:
http://www.intersil.com/data/fn/fn7464.pdf
Author: Daniel Mack <daniel@caiaq.de>
Description
-----------
The ISL29003 is an integrated light sensor with a 16-bit integrating type
ADC, I2C user programmable lux range select for optimized counts/lux, and
I2C multi-function control and monitoring capabilities. The internal ADC
provides 16-bit resolution while rejecting 50Hz and 60Hz flicker caused by
artificial light sources.
The driver allows to set the lux range, the bit resolution, the operational
mode (see below) and the power state of device and can read the current lux
value, of course.
Detection
---------
The ISL29003 does not have an ID register which could be used to identify
it, so the detection routine will just try to read from the configured I2C
addess and consider the device to be present as soon as it ACKs the
transfer.
Sysfs entries
-------------
range:
0: 0 lux to 1000 lux (default)
1: 0 lux to 4000 lux
2: 0 lux to 16,000 lux
3: 0 lux to 64,000 lux
resolution:
0: 2^16 cycles (default)
1: 2^12 cycles
2: 2^8 cycles
3: 2^4 cycles
mode:
0: diode1's current (unsigned 16bit) (default)
1: diode1's current (unsigned 16bit)
2: difference between diodes (l1 - l2, signed 15bit)
power_state:
0: device is disabled (default)
1: device is enabled
lux (read only):
returns the value from the last sensor reading

100
Documentation/networking/vxge.txt Normal file
View file

@ -0,0 +1,100 @@
Neterion's (Formerly S2io) X3100 Series 10GbE PCIe Server Adapter Linux driver
==============================================================================
Contents
--------
1) Introduction
2) Features supported
3) Configurable driver parameters
4) Troubleshooting
1) Introduction:
----------------
This Linux driver supports all Neterion's X3100 series 10 GbE PCIe I/O
Virtualized Server adapters.
The X3100 series supports four modes of operation, configurable via
firmware -
Single function mode
Multi function mode
SRIOV mode
MRIOV mode
The functions share a 10GbE link and the pci-e bus, but hardly anything else
inside the ASIC. Features like independent hw reset, statistics, bandwidth/
priority allocation and guarantees, GRO, TSO, interrupt moderation etc are
supported independently on each function.
(See below for a complete list of features supported for both IPv4 and IPv6)
2) Features supported:
----------------------
i) Single function mode (up to 17 queues)
ii) Multi function mode (up to 17 functions)
iii) PCI-SIG's I/O Virtualization
- Single Root mode: v1.0 (up to 17 functions)
- Multi-Root mode: v1.0 (up to 17 functions)
iv) Jumbo frames
X3100 Series supports MTU up to 9600 bytes, modifiable using
ifconfig command.
v) Offloads supported: (Enabled by default)
Checksum offload (TCP/UDP/IP) on transmit and receive paths
TCP Segmentation Offload (TSO) on transmit path
Generic Receive Offload (GRO) on receive path
vi) MSI-X: (Enabled by default)
Resulting in noticeable performance improvement (up to 7% on certain
platforms).
vii) NAPI: (Enabled by default)
For better Rx interrupt moderation.
viii)RTH (Receive Traffic Hash): (Enabled by default)
Receive side steering for better scaling.
ix) Statistics
Comprehensive MAC-level and software statistics displayed using
"ethtool -S" option.
x) Multiple hardware queues: (Enabled by default)
Up to 17 hardware based transmit and receive data channels, with
multiple steering options (transmit multiqueue enabled by default).
3) Configurable driver parameters:
----------------------------------
i) max_config_dev
Specifies maximum device functions to be enabled.
Valid range: 1-8
ii) max_config_port
Specifies number of ports to be enabled.
Valid range: 1,2
Default: 1
iii)max_config_vpath
Specifies maximum VPATH(s) configured for each device function.
Valid range: 1-17
iv) vlan_tag_strip
Enables/disables vlan tag stripping from all received tagged frames that
are not replicated at the internal L2 switch.
Valid range: 0,1 (disabled, enabled respectively)
Default: 1
v) addr_learn_en
Enable learning the mac address of the guest OS interface in
virtualization environment.
Valid range: 0,1 (disabled, enabled respectively)
Default: 0
4) Troubleshooting:
-------------------
To resolve an issue with the source code or X3100 series adapter, please collect
the statistics, register dumps using ethool, relevant logs and email them to
support@neterion.com.

2
Documentation/powerpc/dts-bindings/fsl/cpm_qe/qe/firmware.txt
View file

@ -1,6 +1,6 @@
* Uploaded QE firmware
If a new firwmare has been uploaded to the QE (usually by the
If a new firmware has been uploaded to the QE (usually by the
boot loader), then a 'firmware' child node should be added to the QE
node. This node provides information on the uploaded firmware that
device drivers may need.

39
Documentation/powerpc/dts-bindings/fsl/upm-nand.txt
View file

@ -5,9 +5,21 @@ Required properties:
- reg : should specify localbus chip select and size used for the chip.
- fsl,upm-addr-offset : UPM pattern offset for the address latch.
- fsl,upm-cmd-offset : UPM pattern offset for the command latch.
- gpios : may specify optional GPIO connected to the Ready-Not-Busy pin.
Example:
Optional properties:
- fsl,upm-wait-flags : add chip-dependent short delays after running the
UPM pattern (0x1), after writing a data byte (0x2) or after
writing out a buffer (0x4).
- fsl,upm-addr-line-cs-offsets : address offsets for multi-chip support.
The corresponding address lines are used to select the chip.
- gpios : may specify optional GPIOs connected to the Ready-Not-Busy pins
(R/B#). For multi-chip devices, "n" GPIO definitions are required
according to the number of chips.
- chip-delay : chip dependent delay for transfering data from array to
read registers (tR). Required if property "gpios" is not used
(R/B# pins not connected).
Examples:
upm@1,0 {
compatible = "fsl,upm-nand";
@ -26,3 +38,26 @@ upm@1,0 {
};
};
};
upm@3,0 {
#address-cells = <0>;
#size-cells = <0>;
compatible = "tqc,tqm8548-upm-nand", "fsl,upm-nand";
reg = <3 0x0 0x800>;
fsl,upm-addr-offset = <0x10>;
fsl,upm-cmd-offset = <0x08>;
/* Multi-chip NAND device */
fsl,upm-addr-line-cs-offsets = <0x0 0x200>;
fsl,upm-wait-flags = <0x5>;
chip-delay = <25>; // in micro-seconds
nand@0 {
#address-cells = <1>;
#size-cells = <1>;
partition@0 {
label = "fs";
reg = <0x00000000 0x10000000>;
};
};
};

46
Documentation/powerpc/dts-bindings/gpio/led.txt
View file

@ -1,15 +1,43 @@
LED connected to GPIO
LEDs connected to GPIO lines
Required properties:
- compatible : should be "gpio-led".
- label : (optional) the label for this LED. If omitted, the label is
- compatible : should be "gpio-leds".
Each LED is represented as a sub-node of the gpio-leds device. Each
node's name represents the name of the corresponding LED.
LED sub-node properties:
- gpios : Should specify the LED's GPIO, see "Specifying GPIO information
for devices" in Documentation/powerpc/booting-without-of.txt. Active
low LEDs should be indicated using flags in the GPIO specifier.
- label : (optional) The label for this LED. If omitted, the label is
taken from the node name (excluding the unit address).
- gpios : should specify LED GPIO.
- linux,default-trigger : (optional) This parameter, if present, is a
string defining the trigger assigned to the LED. Current triggers are:
"backlight" - LED will act as a back-light, controlled by the framebuffer
system
"default-on" - LED will turn on
"heartbeat" - LED "double" flashes at a load average based rate
"ide-disk" - LED indicates disk activity
"timer" - LED flashes at a fixed, configurable rate
Example:
Examples:
led@0 {
compatible = "gpio-led";
label = "hdd";
gpios = <&mcu_pio 0 1>;
leds {
compatible = "gpio-leds";
hdd {
label = "IDE Activity";
gpios = <&mcu_pio 0 1>; /* Active low */
linux,default-trigger = "ide-disk";
};
};
run-control {
compatible = "gpio-leds";
red {
gpios = <&mpc8572 6 0>;
};
green {
gpios = <&mpc8572 7 0>;
};
}

23
Documentation/powerpc/dts-bindings/mmc-spi-slot.txt Normal file
View file

@ -0,0 +1,23 @@
MMC/SD/SDIO slot directly connected to a SPI bus
Required properties:
- compatible : should be "mmc-spi-slot".
- reg : should specify SPI address (chip-select number).
- spi-max-frequency : maximum frequency for this device (Hz).
- voltage-ranges : two cells are required, first cell specifies minimum
slot voltage (mV), second cell specifies maximum slot voltage (mV).
Several ranges could be specified.
- gpios : (optional) may specify GPIOs in this order: Card-Detect GPIO,
Write-Protect GPIO.
Example:
mmc-slot@0 {
compatible = "fsl,mpc8323rdb-mmc-slot",
"mmc-spi-slot";
reg = <0>;
gpios = <&qe_pio_d 14 1
&qe_pio_d 15 0>;
voltage-ranges = <3300 3300>;
spi-max-frequency = <50000000>;
};

2
Documentation/scheduler/sched-rt-group.txt
View file

@ -126,7 +126,7 @@ This uses the /cgroup virtual file system and "/cgroup/<cgroup>/cpu.rt_runtime_u
to control the CPU time reserved for each control group instead.
For more information on working with control groups, you should read
Documentation/cgroups.txt as well.
Documentation/cgroups/cgroups.txt as well.
Group settings are checked against the following limits in order to keep the configuration
schedulable:

15
Documentation/scsi/aacraid.txt
View file

@ -60,17 +60,9 @@ Supported Cards/Chipsets
9005:0285:9005:02d5 Adaptec ASR-2405 (Voodoo40 Lite)
9005:0285:9005:02d6 Adaptec ASR-2445 (Voodoo44 Lite)
9005:0285:9005:02d7 Adaptec ASR-2805 (Voodoo80 Lite)
9005:0285:9005:02d8 Adaptec 5405G (Voodoo40 PM)
9005:0285:9005:02d9 Adaptec 5445G (Voodoo44 PM)
9005:0285:9005:02da Adaptec 5805G (Voodoo80 PM)
9005:0285:9005:02db Adaptec 5085G (Voodoo08 PM)
9005:0285:9005:02dc Adaptec 51245G (Voodoo124 PM)
9005:0285:9005:02dd Adaptec 51645G (Voodoo164 PM)
9005:0285:9005:02de Adaptec 52445G (Voodoo244 PM)
9005:0285:9005:02df Adaptec ASR-2045G (Voodoo04 Lite PM)
9005:0285:9005:02e0 Adaptec ASR-2405G (Voodoo40 Lite PM)
9005:0285:9005:02e1 Adaptec ASR-2445G (Voodoo44 Lite PM)
9005:0285:9005:02e2 Adaptec ASR-2805G (Voodoo80 Lite PM)
9005:0285:9005:02d8 Adaptec 5405Z (Voodoo40 BLBU)
9005:0285:9005:02d9 Adaptec 5445Z (Voodoo44 BLBU)
9005:0285:9005:02da Adaptec 5805Z (Voodoo80 BLBU)
1011:0046:9005:0364 Adaptec 5400S (Mustang)
1011:0046:9005:0365 Adaptec 5400S (Mustang)
9005:0287:9005:0800 Adaptec Themisto (Jupiter)
@ -140,6 +132,7 @@ Deanna Bonds (non-DASD support, PAE fibs and 64 bit,
where fibs that go to the hardware are consistently called hw_fibs and
not just fibs like the name of the driver tracking structure)
Mark Salyzyn <Mark_Salyzyn@adaptec.com> Fixed panic issues and added some new product ids for upcoming hbas. Performance tuning, card failover and bug mitigations.
Achim Leubner <Achim_Leubner@adaptec.com>
Original Driver
-------------------------

174
Documentation/slow-work.txt Normal file
View file

@ -0,0 +1,174 @@
====================================
SLOW WORK ITEM EXECUTION THREAD POOL
====================================
By: David Howells <dhowells@redhat.com>
The slow work item execution thread pool is a pool of threads for performing
things that take a relatively long time, such as making mkdir calls.
Typically, when processing something, these items will spend a lot of time
blocking a thread on I/O, thus making that thread unavailable for doing other
work.
The standard workqueue model is unsuitable for this class of work item as that
limits the owner to a single thread or a single thread per CPU. For some
tasks, however, more threads - or fewer - are required.
There is just one pool per system. It contains no threads unless something
wants to use it - and that something must register its interest first. When
the pool is active, the number of threads it contains is dynamic, varying
between a maximum and minimum setting, depending on the load.
====================
CLASSES OF WORK ITEM
====================
This pool support two classes of work items:
(*) Slow work items.
(*) Very slow work items.
The former are expected to finish much quicker than the latter.
An operation of the very slow class may do a batch combination of several
lookups, mkdirs, and a create for instance.
An operation of the ordinarily slow class may, for example, write stuff or
expand files, provided the time taken to do so isn't too long.
Operations of both types may sleep during execution, thus tying up the thread
loaned to it.
THREAD-TO-CLASS ALLOCATION
--------------------------
Not all the threads in the pool are available to work on very slow work items.
The number will be between one and one fewer than the number of active threads.
This is configurable (see the "Pool Configuration" section).
All the threads are available to work on ordinarily slow work items, but a
percentage of the threads will prefer to work on very slow work items.
The configuration ensures that at least one thread will be available to work on
very slow work items, and at least one thread will be available that won't work
on very slow work items at all.
=====================
USING SLOW WORK ITEMS
=====================
Firstly, a module or subsystem wanting to make use of slow work items must
register its interest:
int ret = slow_work_register_user();
This will return 0 if successful, or a -ve error upon failure.
Slow work items may then be set up by:
(1) Declaring a slow_work struct type variable:
#include <linux/slow-work.h>
struct slow_work myitem;
(2) Declaring the operations to be used for this item:
struct slow_work_ops myitem_ops = {
.get_ref = myitem_get_ref,
.put_ref = myitem_put_ref,
.execute = myitem_execute,
};
[*] For a description of the ops, see section "Item Operations".
(3) Initialising the item:
slow_work_init(&myitem, &myitem_ops);
or:
vslow_work_init(&myitem, &myitem_ops);
depending on its class.
A suitably set up work item can then be enqueued for processing:
int ret = slow_work_enqueue(&myitem);
This will return a -ve error if the thread pool is unable to gain a reference
on the item, 0 otherwise.
The items are reference counted, so there ought to be no need for a flush
operation. When all a module's slow work items have been processed, and the
module has no further interest in the facility, it should unregister its
interest:
slow_work_unregister_user();
===============
ITEM OPERATIONS
===============
Each work item requires a table of operations of type struct slow_work_ops.
All members are required:
(*) Get a reference on an item:
int (*get_ref)(struct slow_work *work);
This allows the thread pool to attempt to pin an item by getting a
reference on it. This function should return 0 if the reference was
granted, or a -ve error otherwise. If an error is returned,
slow_work_enqueue() will fail.
The reference is held whilst the item is queued and whilst it is being
executed. The item may then be requeued with the same reference held, or
the reference will be released.
(*) Release a reference on an item:
void (*put_ref)(struct slow_work *work);
This allows the thread pool to unpin an item by releasing the reference on
it. The thread pool will not touch the item again once this has been
called.
(*) Execute an item:
void (*execute)(struct slow_work *work);
This should perform the work required of the item. It may sleep, it may
perform disk I/O and it may wait for locks.
==================
POOL CONFIGURATION
==================
The slow-work thread pool has a number of configurables:
(*) /proc/sys/kernel/slow-work/min-threads
The minimum number of threads that should be in the pool whilst it is in
use. This may be anywhere between 2 and max-threads.
(*) /proc/sys/kernel/slow-work/max-threads
The maximum number of threads that should in the pool. This may be
anywhere between min-threads and 255 or NR_CPUS * 2, whichever is greater.
(*) /proc/sys/kernel/slow-work/vslow-percentage
The percentage of active threads in the pool that may be used to execute
very slow work items. This may be between 1 and 99. The resultant number
is bounded to between 1 and one fewer than the number of active threads.
This ensures there is always at least one thread that can process very
slow work items, and always at least one thread that won't.

71
Documentation/sound/alsa/soc/jack.txt Normal file
View file

@ -0,0 +1,71 @@
ASoC jack detection
===================
ALSA has a standard API for representing physical jacks to user space,
the kernel side of which can be seen in include/sound/jack.h. ASoC
provides a version of this API adding two additional features:
- It allows more than one jack detection method to work together on one
user visible jack. In embedded systems it is common for multiple
to be present on a single jack but handled by separate bits of
hardware.
- Integration with DAPM, allowing DAPM endpoints to be updated
automatically based on the detected jack status (eg, turning off the
headphone outputs if no headphones are present).
This is done by splitting the jacks up into three things working
together: the jack itself represented by a struct snd_soc_jack, sets of
snd_soc_jack_pins representing DAPM endpoints to update and blocks of
code providing jack reporting mechanisms.
For example, a system may have a stereo headset jack with two reporting
mechanisms, one for the headphone and one for the microphone. Some
systems won't be able to use their speaker output while a headphone is
connected and so will want to make sure to update both speaker and
headphone when the headphone jack status changes.
The jack - struct snd_soc_jack
==============================
This represents a physical jack on the system and is what is visible to
user space. The jack itself is completely passive, it is set up by the
machine driver and updated by jack detection methods.
Jacks are created by the machine driver calling snd_soc_jack_new().
snd_soc_jack_pin
================
These represent a DAPM pin to update depending on some of the status
bits supported by the jack. Each snd_soc_jack has zero or more of these
which are updated automatically. They are created by the machine driver
and associated with the jack using snd_soc_jack_add_pins(). The status
of the endpoint may configured to be the opposite of the jack status if
required (eg, enabling a built in microphone if a microphone is not
connected via a jack).
Jack detection methods
======================
Actual jack detection is done by code which is able to monitor some
input to the system and update a jack by calling snd_soc_jack_report(),
specifying a subset of bits to update. The jack detection code should
be set up by the machine driver, taking configuration for the jack to
update and the set of things to report when the jack is connected.
Often this is done based on the status of a GPIO - a handler for this is
provided by the snd_soc_jack_add_gpio() function. Other methods are
also available, for example integrated into CODECs. One example of
CODEC integrated jack detection can be see in the WM8350 driver.
Each jack may have multiple reporting mechanisms, though it will need at
least one to be useful.
Machine drivers
===============
These are all hooked together by the machine driver depending on the
system hardware. The machine driver will set up the snd_soc_jack and
the list of pins to update then set up one or more jack detection
mechanisms to update that jack based on their current status.

8
Documentation/sparse.txt
View file

@ -42,6 +42,14 @@ sure that bitwise types don't get mixed up (little-endian vs big-endian
vs cpu-endian vs whatever), and there the constant "0" really _is_
special.
__bitwise__ - to be used for relatively compact stuff (gfp_t, etc.) that
is mostly warning-free and is supposed to stay that way. Warnings will
be generated without __CHECK_ENDIAN__.
__bitwise - noisy stuff; in particular, __le*/__be* are that. We really
don't want to drown in noise unless we'd explicitly asked for it.
Getting sparse
~~~~~~~~~~~~~~

2
Documentation/sysctl/00-INDEX
View file

@ -10,6 +10,8 @@ fs.txt
- documentation for /proc/sys/fs/*.
kernel.txt
- documentation for /proc/sys/kernel/*.
net.txt
- documentation for /proc/sys/net/*.
sunrpc.txt
- documentation for /proc/sys/sunrpc/*.
vm.txt

74
Documentation/sysctl/fs.txt
View file

@ -1,5 +1,6 @@
Documentation for /proc/sys/fs/* kernel version 2.2.10
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
(c) 2009, Shen Feng<shen@cn.fujitsu.com>
For general info and legal blurb, please look in README.
@ -14,7 +15,12 @@ kernel. Since some of the files _can_ be used to screw up your
system, it is advisable to read both documentation and source
before actually making adjustments.
1. /proc/sys/fs
----------------------------------------------------------
Currently, these files are in /proc/sys/fs:
- aio-max-nr
- aio-nr
- dentry-state
- dquot-max
- dquot-nr
@ -30,8 +36,15 @@ Currently, these files are in /proc/sys/fs:
- super-max
- super-nr
Documentation for the files in /proc/sys/fs/binfmt_misc is
in Documentation/binfmt_misc.txt.
==============================================================
aio-nr & aio-max-nr:
aio-nr is the running total of the number of events specified on the
io_setup system call for all currently active aio contexts. If aio-nr
reaches aio-max-nr then io_setup will fail with EAGAIN. Note that
raising aio-max-nr does not result in the pre-allocation or re-sizing
of any kernel data structures.
==============================================================
@ -178,3 +191,60 @@ requests. aio-max-nr allows you to change the maximum value
aio-nr can grow to.
==============================================================
2. /proc/sys/fs/binfmt_misc
----------------------------------------------------------
Documentation for the files in /proc/sys/fs/binfmt_misc is
in Documentation/binfmt_misc.txt.
3. /proc/sys/fs/mqueue - POSIX message queues filesystem
----------------------------------------------------------
The "mqueue" filesystem provides the necessary kernel features to enable the
creation of a user space library that implements the POSIX message queues
API (as noted by the MSG tag in the POSIX 1003.1-2001 version of the System
Interfaces specification.)
The "mqueue" filesystem contains values for determining/setting the amount of
resources used by the file system.
/proc/sys/fs/mqueue/queues_max is a read/write file for setting/getting the
maximum number of message queues allowed on the system.
/proc/sys/fs/mqueue/msg_max is a read/write file for setting/getting the
maximum number of messages in a queue value. In fact it is the limiting value
for another (user) limit which is set in mq_open invocation. This attribute of
a queue must be less or equal then msg_max.
/proc/sys/fs/mqueue/msgsize_max is a read/write file for setting/getting the
maximum message size value (it is every message queue's attribute set during
its creation).
4. /proc/sys/fs/epoll - Configuration options for the epoll interface
--------------------------------------------------------
This directory contains configuration options for the epoll(7) interface.
max_user_instances
------------------
This is the maximum number of epoll file descriptors that a single user can
have open at a given time. The default value is 128, and should be enough
for normal users.
max_user_watches
----------------
Every epoll file descriptor can store a number of files to be monitored
for event readiness. Each one of these monitored files constitutes a "watch".
This configuration option sets the maximum number of "watches" that are
allowed for each user.
Each "watch" costs roughly 90 bytes on a 32bit kernel, and roughly 160 bytes
on a 64bit one.
The current default value for max_user_watches is the 1/32 of the available
low memory, divided for the "watch" cost in bytes.

53
Documentation/sysctl/kernel.txt
View file

@ -1,5 +1,6 @@
Documentation for /proc/sys/kernel/* kernel version 2.2.10
(c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
(c) 2009, Shen Feng<shen@cn.fujitsu.com>
For general info and legal blurb, please look in README.
@ -18,6 +19,7 @@ Currently, these files might (depending on your configuration)
show up in /proc/sys/kernel:
- acpi_video_flags
- acct
- auto_msgmni
- core_pattern
- core_uses_pid
- ctrl-alt-del
@ -33,6 +35,7 @@ show up in /proc/sys/kernel:
- msgmax
- msgmnb
- msgmni
- nmi_watchdog
- osrelease
- ostype
- overflowgid
@ -40,6 +43,7 @@ show up in /proc/sys/kernel:
- panic
- pid_max
- powersave-nap [ PPC only ]
- panic_on_unrecovered_nmi
- printk
- randomize_va_space
- real-root-dev ==> Documentation/initrd.txt
@ -55,6 +59,7 @@ show up in /proc/sys/kernel:
- sysrq ==> Documentation/sysrq.txt
- tainted
- threads-max
- unknown_nmi_panic
- version
==============================================================
@ -381,3 +386,51 @@ can be ORed together:
512 - A kernel warning has occurred.
1024 - A module from drivers/staging was loaded.
==============================================================
auto_msgmni:
Enables/Disables automatic recomputing of msgmni upon memory add/remove or
upon ipc namespace creation/removal (see the msgmni description above).
Echoing "1" into this file enables msgmni automatic recomputing.
Echoing "0" turns it off.
auto_msgmni default value is 1.
==============================================================
nmi_watchdog:
Enables/Disables the NMI watchdog on x86 systems. When the value is non-zero
the NMI watchdog is enabled and will continuously test all online cpus to
determine whether or not they are still functioning properly. Currently,
passing "nmi_watchdog=" parameter at boot time is required for this function
to work.
If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel parameter), the
NMI watchdog shares registers with oprofile. By disabling the NMI watchdog,
oprofile may have more registers to utilize.
==============================================================
unknown_nmi_panic:
The value in this file affects behavior of handling NMI. When the value is
non-zero, unknown NMI is trapped and then panic occurs. At that time, kernel
debugging information is displayed on console.
NMI switch that most IA32 servers have fires unknown NMI up, for example.
If a system hangs up, try pressing the NMI switch.
==============================================================
panic_on_unrecovered_nmi:
The default Linux behaviour on an NMI of either memory or unknown is to continue
operation. For many environments such as scientific computing it is preferable
that the box is taken out and the error dealt with than an uncorrected
parity/ECC error get propogated.
A small number of systems do generate NMI's for bizarre random reasons such as
power management so the default is off. That sysctl works like the existing
panic controls already in that directory.

175
Documentation/sysctl/net.txt Normal file
View file

@ -0,0 +1,175 @@
Documentation for /proc/sys/net/* kernel version 2.4.0-test11-pre4
(c) 1999 Terrehon Bowden <terrehon@pacbell.net>
Bodo Bauer <bb@ricochet.net>
(c) 2000 Jorge Nerin <comandante@zaralinux.com>
(c) 2009 Shen Feng <shen@cn.fujitsu.com>
For general info and legal blurb, please look in README.
==============================================================
This file contains the documentation for the sysctl files in
/proc/sys/net and is valid for Linux kernel version 2.4.0-test11-pre4.
The interface to the networking parts of the kernel is located in
/proc/sys/net. The following table shows all possible subdirectories.You may
see only some of them, depending on your kernel's configuration.
Table : Subdirectories in /proc/sys/net
..............................................................................
Directory Content Directory Content
core General parameter appletalk Appletalk protocol
unix Unix domain sockets netrom NET/ROM
802 E802 protocol ax25 AX25
ethernet Ethernet protocol rose X.25 PLP layer
ipv4 IP version 4 x25 X.25 protocol
ipx IPX token-ring IBM token ring
bridge Bridging decnet DEC net
ipv6 IP version 6
..............................................................................
1. /proc/sys/net/core - Network core options
-------------------------------------------------------
rmem_default
------------
The default setting of the socket receive buffer in bytes.
rmem_max
--------
The maximum receive socket buffer size in bytes.
wmem_default
------------
The default setting (in bytes) of the socket send buffer.
wmem_max
--------
The maximum send socket buffer size in bytes.
message_burst and message_cost
------------------------------
These parameters are used to limit the warning messages written to the kernel
log from the networking code. They enforce a rate limit to make a
denial-of-service attack impossible. A higher message_cost factor, results in
fewer messages that will be written. Message_burst controls when messages will
be dropped. The default settings limit warning messages to one every five
seconds.
warnings
--------
This controls console messages from the networking stack that can occur because
of problems on the network like duplicate address or bad checksums. Normally,
this should be enabled, but if the problem persists the messages can be
disabled.
netdev_budget
-------------
Maximum number of packets taken from all interfaces in one polling cycle (NAPI
poll). In one polling cycle interfaces which are registered to polling are
probed in a round-robin manner. The limit of packets in one such probe can be
set per-device via sysfs class/net/<device>/weight .
netdev_max_backlog
------------------
Maximum number of packets, queued on the INPUT side, when the interface
receives packets faster than kernel can process them.
optmem_max
----------
Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
of struct cmsghdr structures with appended data.
2. /proc/sys/net/unix - Parameters for Unix domain sockets
-------------------------------------------------------
There is only one file in this directory.
unix_dgram_qlen limits the max number of datagrams queued in Unix domain
socket's buffer. It will not take effect unless PF_UNIX flag is specified.
3. /proc/sys/net/ipv4 - IPV4 settings
-------------------------------------------------------
Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
descriptions of these entries.
4. Appletalk
-------------------------------------------------------
The /proc/sys/net/appletalk directory holds the Appletalk configuration data
when Appletalk is loaded. The configurable parameters are:
aarp-expiry-time
----------------
The amount of time we keep an ARP entry before expiring it. Used to age out
old hosts.
aarp-resolve-time
-----------------
The amount of time we will spend trying to resolve an Appletalk address.
aarp-retransmit-limit
---------------------
The number of times we will retransmit a query before giving up.
aarp-tick-time
--------------
Controls the rate at which expires are checked.
The directory /proc/net/appletalk holds the list of active Appletalk sockets
on a machine.
The fields indicate the DDP type, the local address (in network:node format)
the remote address, the size of the transmit pending queue, the size of the
received queue (bytes waiting for applications to read) the state and the uid
owning the socket.
/proc/net/atalk_iface lists all the interfaces configured for appletalk.It
shows the name of the interface, its Appletalk address, the network range on
that address (or network number for phase 1 networks), and the status of the
interface.
/proc/net/atalk_route lists each known network route. It lists the target
(network) that the route leads to, the router (may be directly connected), the
route flags, and the device the route is using.
5. IPX
-------------------------------------------------------
The IPX protocol has no tunable values in proc/sys/net.
The IPX protocol does, however, provide proc/net/ipx. This lists each IPX
socket giving the local and remote addresses in Novell format (that is
network:node:port). In accordance with the strange Novell tradition,
everything but the port is in hex. Not_Connected is displayed for sockets that
are not tied to a specific remote address. The Tx and Rx queue sizes indicate
the number of bytes pending for transmission and reception. The state
indicates the state the socket is in and the uid is the owning uid of the
socket.
The /proc/net/ipx_interface file lists all IPX interfaces. For each interface
it gives the network number, the node number, and indicates if the network is
the primary network. It also indicates which device it is bound to (or
Internal for internal networks) and the Frame Type if appropriate. Linux
supports 802.3, 802.2, 802.2 SNAP and DIX (Blue Book) ethernet framing for
IPX.
The /proc/net/ipx_route table holds a list of IPX routes. For each route it
gives the destination network, the router node (or Directly) and the network
address of the router (or Connected) for internal networks.

28
Documentation/sysctl/vm.txt
View file

@ -39,6 +39,8 @@ Currently, these files are in /proc/sys/vm:
- nr_hugepages
- nr_overcommit_hugepages
- nr_pdflush_threads
- nr_pdflush_threads_min
- nr_pdflush_threads_max
- nr_trim_pages (only if CONFIG_MMU=n)
- numa_zonelist_order
- oom_dump_tasks
@ -463,6 +465,32 @@ The default value is 0.
==============================================================
nr_pdflush_threads_min
This value controls the minimum number of pdflush threads.
At boot time, the kernel will create and maintain 'nr_pdflush_threads_min'
threads for the kernel's lifetime.
The default value is 2. The minimum value you can specify is 1, and
the maximum value is the current setting of 'nr_pdflush_threads_max'.
See 'nr_pdflush_threads_max' below for more information.
==============================================================
nr_pdflush_threads_max
This value controls the maximum number of pdflush threads that can be
created. The pdflush algorithm will create a new pdflush thread (up to
this maximum) if no pdflush threads have been available for >= 1 second.
The default value is 8. The minimum value you can specify is the
current value of 'nr_pdflush_threads_min' and the
maximum is 1000.
==============================================================
overcommit_memory:
This value contains a flag that enables memory overcommitment.

7
Documentation/sysrq.txt
View file

@ -81,6 +81,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.:
'i' - Send a SIGKILL to all processes, except for init.
'j' - Forcibly "Just thaw it" - filesystems frozen by the FIFREEZE ioctl.
'k' - Secure Access Key (SAK) Kills all programs on the current virtual
console. NOTE: See important comments below in SAK section.
@ -113,6 +115,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.:
'x' - Used by xmon interface on ppc/powerpc platforms.
'z' - Dump the ftrace buffer
'0'-'9' - Sets the console log level, controlling which kernel messages
will be printed to your console. ('0', for example would make
it so that only emergency messages like PANICs or OOPSes would
@ -160,6 +164,9 @@ t'E'rm and k'I'll are useful if you have some sort of runaway process you
are unable to kill any other way, especially if it's spawning other
processes.
"'J'ust thaw it" is useful if your system becomes unresponsive due to a frozen
(probably root) filesystem via the FIFREEZE ioctl.
* Sometimes SysRq seems to get 'stuck' after using it, what can I do?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
That happens to me, also. I've found that tapping shift, alt, and control

55
Documentation/tomoyo.txt Normal file
View file

@ -0,0 +1,55 @@
--- What is TOMOYO? ---
TOMOYO is a name-based MAC extension (LSM module) for the Linux kernel.
LiveCD-based tutorials are available at
http://tomoyo.sourceforge.jp/en/1.6.x/1st-step/ubuntu8.04-live/
http://tomoyo.sourceforge.jp/en/1.6.x/1st-step/centos5-live/ .
Though these tutorials use non-LSM version of TOMOYO, they are useful for you
to know what TOMOYO is.
--- How to enable TOMOYO? ---
Build the kernel with CONFIG_SECURITY_TOMOYO=y and pass "security=tomoyo" on
kernel's command line.
Please see http://tomoyo.sourceforge.jp/en/2.2.x/ for details.
--- Where is documentation? ---
User <-> Kernel interface documentation is available at
http://tomoyo.sourceforge.jp/en/2.2.x/policy-reference.html .
Materials we prepared for seminars and symposiums are available at
http://sourceforge.jp/projects/tomoyo/docs/?category_id=532&language_id=1 .
Below lists are chosen from three aspects.
What is TOMOYO?
TOMOYO Linux Overview
http://sourceforge.jp/projects/tomoyo/docs/lca2009-takeda.pdf
TOMOYO Linux: pragmatic and manageable security for Linux
http://sourceforge.jp/projects/tomoyo/docs/freedomhectaipei-tomoyo.pdf
TOMOYO Linux: A Practical Method to Understand and Protect Your Own Linux Box
http://sourceforge.jp/projects/tomoyo/docs/PacSec2007-en-no-demo.pdf
What can TOMOYO do?
Deep inside TOMOYO Linux
http://sourceforge.jp/projects/tomoyo/docs/lca2009-kumaneko.pdf
The role of "pathname based access control" in security.
http://sourceforge.jp/projects/tomoyo/docs/lfj2008-bof.pdf
History of TOMOYO?
Realities of Mainlining
http://sourceforge.jp/projects/tomoyo/docs/lfj2008.pdf
--- What is future plan? ---
We believe that inode based security and name based security are complementary
and both should be used together. But unfortunately, so far, we cannot enable
multiple LSM modules at the same time. We feel sorry that you have to give up
SELinux/SMACK/AppArmor etc. when you want to use TOMOYO.
We hope that LSM becomes stackable in future. Meanwhile, you can use non-LSM
version of TOMOYO, available at http://tomoyo.sourceforge.jp/en/1.6.x/ .
LSM version of TOMOYO is a subset of non-LSM version of TOMOYO. We are planning
to port non-LSM version's functionalities to LSM versions.

1102
Documentation/ftrace.txt → Documentation/trace/ftrace.txt
View file

File diff suppressed because it is too large Load diff

Some files were not shown because too many files have changed in this diff Show more