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Greg KH 2005-09-12 12:10:59 -07:00 committed by Greg Kroah-Hartman
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4
COPYING
View file

@ -18,7 +18,7 @@
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
@ -321,7 +321,7 @@ the "copyright" line and a pointer to where the full notice is found.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Also add information on how to contact you by electronic and paper mail.

4
Documentation/00-INDEX
View file

@ -46,6 +46,8 @@ SubmittingPatches
- procedure to get a source patch included into the kernel tree.
VGA-softcursor.txt
- how to change your VGA cursor from a blinking underscore.
applying-patches.txt
- description of various trees and how to apply their patches.
arm/
- directory with info about Linux on the ARM architecture.
basic_profiling.txt
@ -275,7 +277,7 @@ tty.txt
unicode.txt
- info on the Unicode character/font mapping used in Linux.
uml/
- directory with infomation about User Mode Linux.
- directory with information about User Mode Linux.
usb/
- directory with info regarding the Universal Serial Bus.
video4linux/

3
Documentation/CodingStyle
View file

@ -236,6 +236,9 @@ ugly), but try to avoid excess. Instead, put the comments at the head
of the function, telling people what it does, and possibly WHY it does
it.
When commenting the kernel API functions, please use the kerneldoc format.
See the files Documentation/kernel-doc-nano-HOWTO.txt and scripts/kernel-doc
for details.
Chapter 8: You've made a mess of it

2
Documentation/DMA-API.txt
View file

@ -121,7 +121,7 @@ pool's device.
dma_addr_t addr);
This puts memory back into the pool. The pool is what was passed to
the the pool allocation routine; the cpu and dma addresses are what
the pool allocation routine; the cpu and dma addresses are what
were returned when that routine allocated the memory being freed.

151
Documentation/DMA-ISA-LPC.txt Normal file
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@ -0,0 +1,151 @@
DMA with ISA and LPC devices
============================
Pierre Ossman <drzeus@drzeus.cx>
This document describes how to do DMA transfers using the old ISA DMA
controller. Even though ISA is more or less dead today the LPC bus
uses the same DMA system so it will be around for quite some time.
Part I - Headers and dependencies
---------------------------------
To do ISA style DMA you need to include two headers:
#include <linux/dma-mapping.h>
#include <asm/dma.h>
The first is the generic DMA API used to convert virtual addresses to
physical addresses (see Documentation/DMA-API.txt for details).
The second contains the routines specific to ISA DMA transfers. Since
this is not present on all platforms make sure you construct your
Kconfig to be dependent on ISA_DMA_API (not ISA) so that nobody tries
to build your driver on unsupported platforms.
Part II - Buffer allocation
---------------------------
The ISA DMA controller has some very strict requirements on which
memory it can access so extra care must be taken when allocating
buffers.
(You usually need a special buffer for DMA transfers instead of
transferring directly to and from your normal data structures.)
The DMA-able address space is the lowest 16 MB of _physical_ memory.
Also the transfer block may not cross page boundaries (which are 64
or 128 KiB depending on which channel you use).
In order to allocate a piece of memory that satisfies all these
requirements you pass the flag GFP_DMA to kmalloc.
Unfortunately the memory available for ISA DMA is scarce so unless you
allocate the memory during boot-up it's a good idea to also pass
__GFP_REPEAT and __GFP_NOWARN to make the allocater try a bit harder.
(This scarcity also means that you should allocate the buffer as
early as possible and not release it until the driver is unloaded.)
Part III - Address translation
------------------------------
To translate the virtual address to a physical use the normal DMA
API. Do _not_ use isa_virt_to_phys() even though it does the same
thing. The reason for this is that the function isa_virt_to_phys()
will require a Kconfig dependency to ISA, not just ISA_DMA_API which
is really all you need. Remember that even though the DMA controller
has its origins in ISA it is used elsewhere.
Note: x86_64 had a broken DMA API when it came to ISA but has since
been fixed. If your arch has problems then fix the DMA API instead of
reverting to the ISA functions.
Part IV - Channels
------------------
A normal ISA DMA controller has 8 channels. The lower four are for
8-bit transfers and the upper four are for 16-bit transfers.
(Actually the DMA controller is really two separate controllers where
channel 4 is used to give DMA access for the second controller (0-3).
This means that of the four 16-bits channels only three are usable.)
You allocate these in a similar fashion as all basic resources:
extern int request_dma(unsigned int dmanr, const char * device_id);
extern void free_dma(unsigned int dmanr);
The ability to use 16-bit or 8-bit transfers is _not_ up to you as a
driver author but depends on what the hardware supports. Check your
specs or test different channels.
Part V - Transfer data
----------------------
Now for the good stuff, the actual DMA transfer. :)
Before you use any ISA DMA routines you need to claim the DMA lock
using claim_dma_lock(). The reason is that some DMA operations are
not atomic so only one driver may fiddle with the registers at a
time.
The first time you use the DMA controller you should call
clear_dma_ff(). This clears an internal register in the DMA
controller that is used for the non-atomic operations. As long as you
(and everyone else) uses the locking functions then you only need to
reset this once.
Next, you tell the controller in which direction you intend to do the
transfer using set_dma_mode(). Currently you have the options
DMA_MODE_READ and DMA_MODE_WRITE.
Set the address from where the transfer should start (this needs to
be 16-bit aligned for 16-bit transfers) and how many bytes to
transfer. Note that it's _bytes_. The DMA routines will do all the
required translation to values that the DMA controller understands.
The final step is enabling the DMA channel and releasing the DMA
lock.
Once the DMA transfer is finished (or timed out) you should disable
the channel again. You should also check get_dma_residue() to make
sure that all data has been transfered.
Example:
int flags, residue;
flags = claim_dma_lock();
clear_dma_ff();
set_dma_mode(channel, DMA_MODE_WRITE);
set_dma_addr(channel, phys_addr);
set_dma_count(channel, num_bytes);
dma_enable(channel);
release_dma_lock(flags);
while (!device_done());
flags = claim_dma_lock();
dma_disable(channel);
residue = dma_get_residue(channel);
if (residue != 0)
printk(KERN_ERR "driver: Incomplete DMA transfer!"
" %d bytes left!\n", residue);
release_dma_lock(flags);
Part VI - Suspend/resume
------------------------
It is the driver's responsibility to make sure that the machine isn't
suspended while a DMA transfer is in progress. Also, all DMA settings
are lost when the system suspends so if your driver relies on the DMA
controller being in a certain state then you have to restore these
registers upon resume.

4
Documentation/DocBook/journal-api.tmpl
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@ -116,7 +116,7 @@ filesystem. Almost.
You still need to actually journal your filesystem changes, this
is done by wrapping them into transactions. Additionally you
also need to wrap the modification of each of the the buffers
also need to wrap the modification of each of the buffers
with calls to the journal layer, so it knows what the modifications
you are actually making are. To do this use journal_start() which
returns a transaction handle.
@ -128,7 +128,7 @@ and its counterpart journal_stop(), which indicates the end of a transaction
are nestable calls, so you can reenter a transaction if necessary,
but remember you must call journal_stop() the same number of times as
journal_start() before the transaction is completed (or more accurately
leaves the the update phase). Ext3/VFS makes use of this feature to simplify
leaves the update phase). Ext3/VFS makes use of this feature to simplify
quota support.
</para>

314
Documentation/DocBook/kernel-hacking.tmpl
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@ -8,8 +8,7 @@
<authorgroup>
<author>
<firstname>Paul</firstname>
<othername>Rusty</othername>
<firstname>Rusty</firstname>
<surname>Russell</surname>
<affiliation>
<address>
@ -20,7 +19,7 @@
</authorgroup>
<copyright>
<year>2001</year>
<year>2005</year>
<holder>Rusty Russell</holder>
</copyright>
@ -64,7 +63,7 @@
<chapter id="introduction">
<title>Introduction</title>
<para>
Welcome, gentle reader, to Rusty's Unreliable Guide to Linux
Welcome, gentle reader, to Rusty's Remarkably Unreliable Guide to Linux
Kernel Hacking. This document describes the common routines and
general requirements for kernel code: its goal is to serve as a
primer for Linux kernel development for experienced C
@ -96,13 +95,13 @@
<listitem>
<para>
not associated with any process, serving a softirq, tasklet or bh;
not associated with any process, serving a softirq or tasklet;
</para>
</listitem>
<listitem>
<para>
running in kernel space, associated with a process;
running in kernel space, associated with a process (user context);
</para>
</listitem>
@ -114,11 +113,12 @@
</itemizedlist>
<para>
There is a strict ordering between these: other than the last
category (userspace) each can only be pre-empted by those above.
For example, while a softirq is running on a CPU, no other
softirq will pre-empt it, but a hardware interrupt can. However,
any other CPUs in the system execute independently.
There is an ordering between these. The bottom two can preempt
each other, but above that is a strict hierarchy: each can only be
preempted by the ones above it. For example, while a softirq is
running on a CPU, no other softirq will preempt it, but a hardware
interrupt can. However, any other CPUs in the system execute
independently.
</para>
<para>
@ -130,10 +130,10 @@
<title>User Context</title>
<para>
User context is when you are coming in from a system call or
other trap: you can sleep, and you own the CPU (except for
interrupts) until you call <function>schedule()</function>.
In other words, user context (unlike userspace) is not pre-emptable.
User context is when you are coming in from a system call or other
trap: like userspace, you can be preempted by more important tasks
and by interrupts. You can sleep, by calling
<function>schedule()</function>.
</para>
<note>
@ -153,7 +153,7 @@
<caution>
<para>
Beware that if you have interrupts or bottom halves disabled
Beware that if you have preemption or softirqs disabled
(see below), <function>in_interrupt()</function> will return a
false positive.
</para>
@ -168,10 +168,10 @@
<hardware>keyboard</hardware> are examples of real
hardware which produce interrupts at any time. The kernel runs
interrupt handlers, which services the hardware. The kernel
guarantees that this handler is never re-entered: if another
guarantees that this handler is never re-entered: if the same
interrupt arrives, it is queued (or dropped). Because it
disables interrupts, this handler has to be fast: frequently it
simply acknowledges the interrupt, marks a `software interrupt'
simply acknowledges the interrupt, marks a 'software interrupt'
for execution and exits.
</para>
@ -188,60 +188,52 @@
</sect1>
<sect1 id="basics-softirqs">
<title>Software Interrupt Context: Bottom Halves, Tasklets, softirqs</title>
<title>Software Interrupt Context: Softirqs and Tasklets</title>
<para>
Whenever a system call is about to return to userspace, or a
hardware interrupt handler exits, any `software interrupts'
hardware interrupt handler exits, any 'software interrupts'
which are marked pending (usually by hardware interrupts) are
run (<filename>kernel/softirq.c</filename>).
</para>
<para>
Much of the real interrupt handling work is done here. Early in
the transition to <acronym>SMP</acronym>, there were only `bottom
the transition to <acronym>SMP</acronym>, there were only 'bottom
halves' (BHs), which didn't take advantage of multiple CPUs. Shortly
after we switched from wind-up computers made of match-sticks and snot,
we abandoned this limitation.
we abandoned this limitation and switched to 'softirqs'.
</para>
<para>
<filename class="headerfile">include/linux/interrupt.h</filename> lists the
different BH's. No matter how many CPUs you have, no two BHs will run at
the same time. This made the transition to SMP simpler, but sucks hard for
scalable performance. A very important bottom half is the timer
BH (<filename class="headerfile">include/linux/timer.h</filename>): you
can register to have it call functions for you in a given length of time.
different softirqs. A very important softirq is the
timer softirq (<filename
class="headerfile">include/linux/timer.h</filename>): you can
register to have it call functions for you in a given length of
time.
</para>
<para>
2.3.43 introduced softirqs, and re-implemented the (now
deprecated) BHs underneath them. Softirqs are fully-SMP
versions of BHs: they can run on as many CPUs at once as
required. This means they need to deal with any races in shared
data using their own locks. A bitmask is used to keep track of
which are enabled, so the 32 available softirqs should not be
used up lightly. (<emphasis>Yes</emphasis>, people will
notice).
</para>
<para>
tasklets (<filename class="headerfile">include/linux/interrupt.h</filename>)
are like softirqs, except they are dynamically-registrable (meaning you
can have as many as you want), and they also guarantee that any tasklet
will only run on one CPU at any time, although different tasklets can
run simultaneously (unlike different BHs).
Softirqs are often a pain to deal with, since the same softirq
will run simultaneously on more than one CPU. For this reason,
tasklets (<filename
class="headerfile">include/linux/interrupt.h</filename>) are more
often used: they are dynamically-registrable (meaning you can have
as many as you want), and they also guarantee that any tasklet
will only run on one CPU at any time, although different tasklets
can run simultaneously.
</para>
<caution>
<para>
The name `tasklet' is misleading: they have nothing to do with `tasks',
The name 'tasklet' is misleading: they have nothing to do with 'tasks',
and probably more to do with some bad vodka Alexey Kuznetsov had at the
time.
</para>
</caution>
<para>
You can tell you are in a softirq (or bottom half, or tasklet)
You can tell you are in a softirq (or tasklet)
using the <function>in_softirq()</function> macro
(<filename class="headerfile">include/linux/interrupt.h</filename>).
</para>
@ -288,11 +280,10 @@
<term>A rigid stack limit</term>
<listitem>
<para>
The kernel stack is about 6K in 2.2 (for most
architectures: it's about 14K on the Alpha), and shared
with interrupts so you can't use it all. Avoid deep
recursion and huge local arrays on the stack (allocate
them dynamically instead).
Depending on configuration options the kernel stack is about 3K to 6K for most 32-bit architectures: it's
about 14K on most 64-bit archs, and often shared with interrupts
so you can't use it all. Avoid deep recursion and huge local
arrays on the stack (allocate them dynamically instead).
</para>
</listitem>
</varlistentry>
@ -339,7 +330,7 @@ asmlinkage long sys_mycall(int arg)
<para>
If all your routine does is read or write some parameter, consider
implementing a <function>sysctl</function> interface instead.
implementing a <function>sysfs</function> interface instead.
</para>
<para>
@ -417,7 +408,10 @@ cond_resched(); /* Will sleep */
</para>
<para>
You will eventually lock up your box if you break these rules.
You should always compile your kernel
<symbol>CONFIG_DEBUG_SPINLOCK_SLEEP</symbol> on, and it will warn
you if you break these rules. If you <emphasis>do</emphasis> break
the rules, you will eventually lock up your box.
</para>
<para>
@ -515,8 +509,7 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
success).
</para>
</caution>
[Yes, this moronic interface makes me cringe. Please submit a
patch and become my hero --RR.]
[Yes, this moronic interface makes me cringe. The flamewar comes up every year or so. --RR.]
</para>
<para>
The functions may sleep implicitly. This should never be called
@ -587,10 +580,11 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
</variablelist>
<para>
If you see a <errorname>kmem_grow: Called nonatomically from int
</errorname> warning message you called a memory allocation function
from interrupt context without <constant>GFP_ATOMIC</constant>.
You should really fix that. Run, don't walk.
If you see a <errorname>sleeping function called from invalid
context</errorname> warning message, then maybe you called a
sleeping allocation function from interrupt context without
<constant>GFP_ATOMIC</constant>. You should really fix that.
Run, don't walk.
</para>
<para>
@ -639,16 +633,16 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
</sect1>
<sect1 id="routines-udelay">
<title><function>udelay()</function>/<function>mdelay()</function>
<title><function>mdelay()</function>/<function>udelay()</function>
<filename class="headerfile">include/asm/delay.h</filename>
<filename class="headerfile">include/linux/delay.h</filename>
</title>
<para>
The <function>udelay()</function> function can be used for small pauses.
Do not use large values with <function>udelay()</function> as you risk
The <function>udelay()</function> and <function>ndelay()</function> functions can be used for small pauses.
Do not use large values with them as you risk
overflow - the helper function <function>mdelay()</function> is useful
here, or even consider <function>schedule_timeout()</function>.
here, or consider <function>msleep()</function>.
</para>
</sect1>
@ -698,8 +692,8 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
These routines disable soft interrupts on the local CPU, and
restore them. They are reentrant; if soft interrupts were
disabled before, they will still be disabled after this pair
of functions has been called. They prevent softirqs, tasklets
and bottom halves from running on the current CPU.
of functions has been called. They prevent softirqs and tasklets
from running on the current CPU.
</para>
</sect1>
@ -708,10 +702,16 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<filename class="headerfile">include/asm/smp.h</filename></title>
<para>
<function>smp_processor_id()</function> returns the current
processor number, between 0 and <symbol>NR_CPUS</symbol> (the
maximum number of CPUs supported by Linux, currently 32). These
values are not necessarily continuous.
<function>get_cpu()</function> disables preemption (so you won't
suddenly get moved to another CPU) and returns the current
processor number, between 0 and <symbol>NR_CPUS</symbol>. Note
that the CPU numbers are not necessarily continuous. You return
it again with <function>put_cpu()</function> when you are done.
</para>
<para>
If you know you cannot be preempted by another task (ie. you are
in interrupt context, or have preemption disabled) you can use
smp_processor_id().
</para>
</sect1>
@ -722,19 +722,14 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<para>
After boot, the kernel frees up a special section; functions
marked with <type>__init</type> and data structures marked with
<type>__initdata</type> are dropped after boot is complete (within
modules this directive is currently ignored). <type>__exit</type>
<type>__initdata</type> are dropped after boot is complete: similarly
modules discard this memory after initialization. <type>__exit</type>
is used to declare a function which is only required on exit: the
function will be dropped if this file is not compiled as a module.
See the header file for use. Note that it makes no sense for a function
marked with <type>__init</type> to be exported to modules with
<function>EXPORT_SYMBOL()</function> - this will break.
</para>
<para>
Static data structures marked as <type>__initdata</type> must be initialised
(as opposed to ordinary static data which is zeroed BSS) and cannot be
<type>const</type>.
</para>
</sect1>
@ -762,9 +757,8 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<para>
The function can return a negative error number to cause
module loading to fail (unfortunately, this has no effect if
the module is compiled into the kernel). For modules, this is
called in user context, with interrupts enabled, and the
kernel lock held, so it can sleep.
the module is compiled into the kernel). This function is
called in user context with interrupts enabled, so it can sleep.
</para>
</sect1>
@ -779,6 +773,34 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
reached zero. This function can also sleep, but cannot fail:
everything must be cleaned up by the time it returns.
</para>
<para>
Note that this macro is optional: if it is not present, your
module will not be removable (except for 'rmmod -f').
</para>
</sect1>
<sect1 id="routines-module-use-counters">
<title> <function>try_module_get()</function>/<function>module_put()</function>
<filename class="headerfile">include/linux/module.h</filename></title>
<para>
These manipulate the module usage count, to protect against
removal (a module also can't be removed if another module uses one
of its exported symbols: see below). Before calling into module
code, you should call <function>try_module_get()</function> on
that module: if it fails, then the module is being removed and you
should act as if it wasn't there. Otherwise, you can safely enter
the module, and call <function>module_put()</function> when you're
finished.
</para>
<para>
Most registerable structures have an
<structfield>owner</structfield> field, such as in the
<structname>file_operations</structname> structure. Set this field
to the macro <symbol>THIS_MODULE</symbol>.
</para>
</sect1>
<!-- add info on new-style module refcounting here -->
@ -821,7 +843,7 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
There is a macro to do this:
<function>wait_event_interruptible()</function>
<filename class="headerfile">include/linux/sched.h</filename> The
<filename class="headerfile">include/linux/wait.h</filename> The
first argument is the wait queue head, and the second is an
expression which is evaluated; the macro returns
<returnvalue>0</returnvalue> when this expression is true, or
@ -847,10 +869,11 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<para>
Call <function>wake_up()</function>
<filename class="headerfile">include/linux/sched.h</filename>;,
<filename class="headerfile">include/linux/wait.h</filename>;,
which will wake up every process in the queue. The exception is
if one has <constant>TASK_EXCLUSIVE</constant> set, in which case
the remainder of the queue will not be woken.
the remainder of the queue will not be woken. There are other variants
of this basic function available in the same header.
</para>
</sect1>
</chapter>
@ -863,7 +886,7 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
first class of operations work on <type>atomic_t</type>
<filename class="headerfile">include/asm/atomic.h</filename>; this
contains a signed integer (at least 24 bits long), and you must use
contains a signed integer (at least 32 bits long), and you must use
these functions to manipulate or read atomic_t variables.
<function>atomic_read()</function> and
<function>atomic_set()</function> get and set the counter,
@ -882,13 +905,12 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<para>
Note that these functions are slower than normal arithmetic, and
so should not be used unnecessarily. On some platforms they
are much slower, like 32-bit Sparc where they use a spinlock.
so should not be used unnecessarily.
</para>
<para>
The second class of atomic operations is atomic bit operations on a
<type>long</type>, defined in
The second class of atomic operations is atomic bit operations on an
<type>unsigned long</type>, defined in
<filename class="headerfile">include/linux/bitops.h</filename>. These
operations generally take a pointer to the bit pattern, and a bit
@ -899,7 +921,7 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<function>test_and_clear_bit()</function> and
<function>test_and_change_bit()</function> do the same thing,
except return true if the bit was previously set; these are
particularly useful for very simple locking.
particularly useful for atomically setting flags.
</para>
<para>
@ -907,12 +929,6 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
than BITS_PER_LONG. The resulting behavior is strange on big-endian
platforms though so it is a good idea not to do this.
</para>
<para>
Note that the order of bits depends on the architecture, and in
particular, the bitfield passed to these operations must be at
least as large as a <type>long</type>.
</para>
</chapter>
<chapter id="symbols">
@ -932,11 +948,8 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<filename class="headerfile">include/linux/module.h</filename></title>
<para>
This is the classic method of exporting a symbol, and it works
for both modules and non-modules. In the kernel all these
declarations are often bundled into a single file to help
genksyms (which searches source files for these declarations).
See the comment on genksyms and Makefiles below.
This is the classic method of exporting a symbol: dynamically
loaded modules will be able to use the symbol as normal.
</para>
</sect1>
@ -949,7 +962,8 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
symbols exported by <function>EXPORT_SYMBOL_GPL()</function> can
only be seen by modules with a
<function>MODULE_LICENSE()</function> that specifies a GPL
compatible license.
compatible license. It implies that the function is considered
an internal implementation issue, and not really an interface.
</para>
</sect1>
</chapter>
@ -962,12 +976,13 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
<filename class="headerfile">include/linux/list.h</filename></title>
<para>
There are three sets of linked-list routines in the kernel
headers, but this one seems to be winning out (and Linus has
used it). If you don't have some particular pressing need for
a single list, it's a good choice. In fact, I don't care
whether it's a good choice or not, just use it so we can get
rid of the others.
There used to be three sets of linked-list routines in the kernel
headers, but this one is the winner. If you don't have some
particular pressing need for a single list, it's a good choice.
</para>
<para>
In particular, <function>list_for_each_entry</function> is useful.
</para>
</sect1>
@ -979,14 +994,13 @@ printk(KERN_INFO "my ip: %d.%d.%d.%d\n", NIPQUAD(ipaddress));
convention, and return <returnvalue>0</returnvalue> for success,
and a negative error number
(eg. <returnvalue>-EFAULT</returnvalue>) for failure. This can be
unintuitive at first, but it's fairly widespread in the networking
code, for example.
unintuitive at first, but it's fairly widespread in the kernel.
</para>
<para>
The filesystem code uses <function>ERR_PTR()</function>
Using <function>ERR_PTR()</function>
<filename class="headerfile">include/linux/fs.h</filename>; to
<filename class="headerfile">include/linux/err.h</filename>; to
encode a negative error number into a pointer, and
<function>IS_ERR()</function> and <function>PTR_ERR()</function>
to get it back out again: avoids a separate pointer parameter for
@ -1040,7 +1054,7 @@ static struct block_device_operations opt_fops = {
supported, due to lack of general use, but the following are
considered standard (see the GCC info page section "C
Extensions" for more details - Yes, really the info page, the
man page is only a short summary of the stuff in info):
man page is only a short summary of the stuff in info).
</para>
<itemizedlist>
<listitem>
@ -1091,7 +1105,7 @@ static struct block_device_operations opt_fops = {
</listitem>
<listitem>
<para>
Function names as strings (__FUNCTION__)
Function names as strings (__func__).
</para>
</listitem>
<listitem>
@ -1164,63 +1178,35 @@ static struct block_device_operations opt_fops = {
<listitem>
<para>
Usually you want a configuration option for your kernel hack.
Edit <filename>Config.in</filename> in the appropriate directory
(but under <filename>arch/</filename> it's called
<filename>config.in</filename>). The Config Language used is not
bash, even though it looks like bash; the safe way is to use only
the constructs that you already see in
<filename>Config.in</filename> files (see
<filename>Documentation/kbuild/kconfig-language.txt</filename>).
It's good to run "make xconfig" at least once to test (because
it's the only one with a static parser).
</para>
<para>
Variables which can be Y or N use <type>bool</type> followed by a
tagline and the config define name (which must start with
CONFIG_). The <type>tristate</type> function is the same, but
allows the answer M (which defines
<symbol>CONFIG_foo_MODULE</symbol> in your source, instead of
<symbol>CONFIG_FOO</symbol>) if <symbol>CONFIG_MODULES</symbol>
is enabled.
Edit <filename>Kconfig</filename> in the appropriate directory.
The Config language is simple to use by cut and paste, and there's
complete documentation in
<filename>Documentation/kbuild/kconfig-language.txt</filename>.
</para>
<para>
You may well want to make your CONFIG option only visible if
<symbol>CONFIG_EXPERIMENTAL</symbol> is enabled: this serves as a
warning to users. There many other fancy things you can do: see
the various <filename>Config.in</filename> files for ideas.
the various <filename>Kconfig</filename> files for ideas.
</para>
<para>
In your description of the option, make sure you address both the
expert user and the user who knows nothing about your feature. Mention
incompatibilities and issues here. <emphasis> Definitely
</emphasis> end your description with <quote> if in doubt, say N
</quote> (or, occasionally, `Y'); this is for people who have no
idea what you are talking about.
</para>
</listitem>
<listitem>
<para>
Edit the <filename>Makefile</filename>: the CONFIG variables are
exported here so you can conditionalize compilation with `ifeq'.
If your file exports symbols then add the names to
<varname>export-objs</varname> so that genksyms will find them.
<caution>
<para>
There is a restriction on the kernel build system that objects
which export symbols must have globally unique names.
If your object does not have a globally unique name then the
standard fix is to move the
<function>EXPORT_SYMBOL()</function> statements to their own
object with a unique name.
This is why several systems have separate exporting objects,
usually suffixed with ksyms.
</para>
</caution>
</para>
</listitem>
<listitem>
<para>
Document your option in Documentation/Configure.help. Mention
incompatibilities and issues here. <emphasis> Definitely
</emphasis> end your description with <quote> if in doubt, say N
</quote> (or, occasionally, `Y'); this is for people who have no
idea what you are talking about.
exported here so you can usually just add a "obj-$(CONFIG_xxx) +=
xxx.o" line. The syntax is documented in
<filename>Documentation/kbuild/makefiles.txt</filename>.
</para>
</listitem>
@ -1253,20 +1239,12 @@ static struct block_device_operations opt_fops = {
</para>
<para>
<filename>include/linux/brlock.h:</filename>
<filename>include/asm-i386/delay.h:</filename>
</para>
<programlisting>
extern inline void br_read_lock (enum brlock_indices idx)
{
/*
* This causes a link-time bug message if an
* invalid index is used:
*/
if (idx >= __BR_END)
__br_lock_usage_bug();
read_lock(&amp;__brlock_array[smp_processor_id()][idx]);
}
#define ndelay(n) (__builtin_constant_p(n) ? \
((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \
__ndelay(n))
</programlisting>
<para>

2
Documentation/DocBook/usb.tmpl
View file

@ -841,7 +841,7 @@ usbdev_ioctl (int fd, int ifno, unsigned request, void *param)
File modification time is not updated by this request.
</para><para>
Those struct members are from some interface descriptor
applying to the the current configuration.
applying to the current configuration.
The interface number is the bInterfaceNumber value, and
the altsetting number is the bAlternateSetting value.
(This resets each endpoint in the interface.)

2
Documentation/MSI-HOWTO.txt
View file

@ -430,7 +430,7 @@ which may result in system hang. The software driver of specific
MSI-capable hardware is responsible for whether calling
pci_enable_msi or not. A return of zero indicates the kernel
successfully initializes the MSI/MSI-X capability structure of the
device funtion. The device function is now running on MSI/MSI-X mode.
device function. The device function is now running on MSI/MSI-X mode.
5.6 How to tell whether MSI/MSI-X is enabled on device function

36
Documentation/RCU/RTFP.txt
View file

@ -2,7 +2,8 @@ Read the F-ing Papers!
This document describes RCU-related publications, and is followed by
the corresponding bibtex entries.
the corresponding bibtex entries. A number of the publications may
be found at http://www.rdrop.com/users/paulmck/RCU/.
The first thing resembling RCU was published in 1980, when Kung and Lehman
[Kung80] recommended use of a garbage collector to defer destruction
@ -113,6 +114,10 @@ describing how to make RCU safe for soft-realtime applications [Sarma04c],
and a paper describing SELinux performance with RCU [JamesMorris04b].
2005 has seen further adaptation of RCU to realtime use, permitting
preemption of RCU realtime critical sections [PaulMcKenney05a,
PaulMcKenney05b].
Bibtex Entries
@article{Kung80
@ -410,3 +415,32 @@ Oregon Health and Sciences University"
\url{http://www.livejournal.com/users/james_morris/2153.html}
[Viewed December 10, 2004]"
}
@unpublished{PaulMcKenney05a
,Author="Paul E. McKenney"
,Title="{[RFC]} {RCU} and {CONFIG\_PREEMPT\_RT} progress"
,month="May"
,year="2005"
,note="Available:
\url{http://lkml.org/lkml/2005/5/9/185}
[Viewed May 13, 2005]"
,annotation="
First publication of working lock-based deferred free patches
for the CONFIG_PREEMPT_RT environment.
"
}
@conference{PaulMcKenney05b
,Author="Paul E. McKenney and Dipankar Sarma"
,Title="Towards Hard Realtime Response from the Linux Kernel on SMP Hardware"
,Booktitle="linux.conf.au 2005"
,month="April"
,year="2005"
,address="Canberra, Australia"
,note="Available:
\url{http://www.rdrop.com/users/paulmck/RCU/realtimeRCU.2005.04.23a.pdf}
[Viewed May 13, 2005]"
,annotation="
Realtime turns into making RCU yet more realtime friendly.
"
}

73
Documentation/RCU/UP.txt
View file

@ -8,7 +8,7 @@ is that since there is only one CPU, it should not be necessary to
wait for anything else to get done, since there are no other CPUs for
anything else to be happening on. Although this approach will -sort- -of-
work a surprising amount of the time, it is a very bad idea in general.
This document presents two examples that demonstrate exactly how bad an
This document presents three examples that demonstrate exactly how bad an
idea this is.
@ -26,6 +26,9 @@ from softirq, the list scan would find itself referencing a newly freed
element B. This situation can greatly decrease the life expectancy of
your kernel.
This same problem can occur if call_rcu() is invoked from a hardware
interrupt handler.
Example 2: Function-Call Fatality
@ -44,8 +47,37 @@ its arguments would cause it to fail to make the fundamental guarantee
underlying RCU, namely that call_rcu() defers invoking its arguments until
all RCU read-side critical sections currently executing have completed.
Quick Quiz: why is it -not- legal to invoke synchronize_rcu() in
this case?
Quick Quiz #1: why is it -not- legal to invoke synchronize_rcu() in
this case?
Example 3: Death by Deadlock
Suppose that call_rcu() is invoked while holding a lock, and that the
callback function must acquire this same lock. In this case, if
call_rcu() were to directly invoke the callback, the result would
be self-deadlock.
In some cases, it would possible to restructure to code so that
the call_rcu() is delayed until after the lock is released. However,
there are cases where this can be quite ugly:
1. If a number of items need to be passed to call_rcu() within
the same critical section, then the code would need to create
a list of them, then traverse the list once the lock was
released.
2. In some cases, the lock will be held across some kernel API,
so that delaying the call_rcu() until the lock is released
requires that the data item be passed up via a common API.
It is far better to guarantee that callbacks are invoked
with no locks held than to have to modify such APIs to allow
arbitrary data items to be passed back up through them.
If call_rcu() directly invokes the callback, painful locking restrictions
or API changes would be required.
Quick Quiz #2: What locking restriction must RCU callbacks respect?
Summary
@ -53,12 +85,35 @@ Summary
Permitting call_rcu() to immediately invoke its arguments or permitting
synchronize_rcu() to immediately return breaks RCU, even on a UP system.
So do not do it! Even on a UP system, the RCU infrastructure -must-
respect grace periods.
respect grace periods, and -must- invoke callbacks from a known environment
in which no locks are held.
Answer to Quick Quiz
Answer to Quick Quiz #1:
Why is it -not- legal to invoke synchronize_rcu() in this case?
The calling function is scanning an RCU-protected linked list, and
is therefore within an RCU read-side critical section. Therefore,
the called function has been invoked within an RCU read-side critical
section, and is not permitted to block.
Because the calling function is scanning an RCU-protected linked
list, and is therefore within an RCU read-side critical section.
Therefore, the called function has been invoked within an RCU
read-side critical section, and is not permitted to block.
Answer to Quick Quiz #2:
What locking restriction must RCU callbacks respect?
Any lock that is acquired within an RCU callback must be
acquired elsewhere using an _irq variant of the spinlock
primitive. For example, if "mylock" is acquired by an
RCU callback, then a process-context acquisition of this
lock must use something like spin_lock_irqsave() to
acquire the lock.
If the process-context code were to simply use spin_lock(),
then, since RCU callbacks can be invoked from softirq context,
the callback might be called from a softirq that interrupted
the process-context critical section. This would result in
self-deadlock.
This restriction might seem gratuitous, since very few RCU
callbacks acquire locks directly. However, a great many RCU
callbacks do acquire locks -indirectly-, for example, via
the kfree() primitive.

23
Documentation/RCU/checklist.txt
View file

@ -43,6 +43,10 @@ over a rather long period of time, but improvements are always welcome!
rcu_read_lock_bh()) in the read-side critical sections,
and are also an excellent aid to readability.
As a rough rule of thumb, any dereference of an RCU-protected
pointer must be covered by rcu_read_lock() or rcu_read_lock_bh()
or by the appropriate update-side lock.
3. Does the update code tolerate concurrent accesses?
The whole point of RCU is to permit readers to run without
@ -90,7 +94,11 @@ over a rather long period of time, but improvements are always welcome!
The rcu_dereference() primitive is used by the various
"_rcu()" list-traversal primitives, such as the
list_for_each_entry_rcu().
list_for_each_entry_rcu(). Note that it is perfectly
legal (if redundant) for update-side code to use
rcu_dereference() and the "_rcu()" list-traversal
primitives. This is particularly useful in code
that is common to readers and updaters.
b. If the list macros are being used, the list_add_tail_rcu()
and list_add_rcu() primitives must be used in order
@ -150,16 +158,9 @@ over a rather long period of time, but improvements are always welcome!
Use of the _rcu() list-traversal primitives outside of an
RCU read-side critical section causes no harm other than
a slight performance degradation on Alpha CPUs and some
confusion on the part of people trying to read the code.
Another way of thinking of this is "If you are holding the
lock that prevents the data structure from changing, why do
you also need RCU-based protection?" That said, there may
well be situations where use of the _rcu() list-traversal
primitives while the update-side lock is held results in
simpler and more maintainable code. The jury is still out
on this question.
a slight performance degradation on Alpha CPUs. It can
also be quite helpful in reducing code bloat when common
code is shared between readers and updaters.
10. Conversely, if you are in an RCU read-side critical section,
you -must- use the "_rcu()" variants of the list macros.

48
Documentation/RCU/rcu.txt
View file

@ -64,6 +64,54 @@ o I hear that RCU is patented? What is with that?
Of these, one was allowed to lapse by the assignee, and the
others have been contributed to the Linux kernel under GPL.
o I hear that RCU needs work in order to support realtime kernels?
Yes, work in progress.
o Where can I find more information on RCU?
See the RTFP.txt file in this directory.
Or point your browser at http://www.rdrop.com/users/paulmck/RCU/.
o What are all these files in this directory?
NMI-RCU.txt
Describes how to use RCU to implement dynamic
NMI handlers, which can be revectored on the fly,
without rebooting.
RTFP.txt
List of RCU-related publications and web sites.
UP.txt
Discussion of RCU usage in UP kernels.
arrayRCU.txt
Describes how to use RCU to protect arrays, with
resizeable arrays whose elements reference other
data structures being of the most interest.
checklist.txt
Lists things to check for when inspecting code that
uses RCU.
listRCU.txt
Describes how to use RCU to protect linked lists.
This is the simplest and most common use of RCU
in the Linux kernel.
rcu.txt
You are reading it!
whatisRCU.txt
Overview of how the RCU implementation works. Along
the way, presents a conceptual view of RCU.

74
Documentation/RCU/rcuref.txt Normal file
View file

@ -0,0 +1,74 @@
Refcounter framework for elements of lists/arrays protected by
RCU.
Refcounting on elements of lists which are protected by traditional
reader/writer spinlocks or semaphores are straight forward as in:
1. 2.
add() search_and_reference()
{ {
alloc_object read_lock(&list_lock);
... search_for_element
atomic_set(&el->rc, 1); atomic_inc(&el->rc);
write_lock(&list_lock); ...
add_element read_unlock(&list_lock);
... ...
write_unlock(&list_lock); }
}
3. 4.
release_referenced() delete()
{ {
... write_lock(&list_lock);
atomic_dec(&el->rc, relfunc) ...
... delete_element
} write_unlock(&list_lock);
...
if (atomic_dec_and_test(&el->rc))
kfree(el);
...
}
If this list/array is made lock free using rcu as in changing the
write_lock in add() and delete() to spin_lock and changing read_lock
in search_and_reference to rcu_read_lock(), the rcuref_get in
search_and_reference could potentially hold reference to an element which
has already been deleted from the list/array. rcuref_lf_get_rcu takes
care of this scenario. search_and_reference should look as;
1. 2.
add() search_and_reference()
{ {
alloc_object rcu_read_lock();
... search_for_element
atomic_set(&el->rc, 1); if (rcuref_inc_lf(&el->rc)) {
write_lock(&list_lock); rcu_read_unlock();
return FAIL;
add_element }
... ...
write_unlock(&list_lock); rcu_read_unlock();
} }
3. 4.
release_referenced() delete()
{ {
... write_lock(&list_lock);
rcuref_dec(&el->rc, relfunc) ...
... delete_element
} write_unlock(&list_lock);
...
if (rcuref_dec_and_test(&el->rc))
call_rcu(&el->head, el_free);
...
}
Sometimes, reference to the element need to be obtained in the
update (write) stream. In such cases, rcuref_inc_lf might be an overkill
since the spinlock serialising list updates are held. rcuref_inc
is to be used in such cases.
For arches which do not have cmpxchg rcuref_inc_lf
api uses a hashed spinlock implementation and the same hashed spinlock
is acquired in all rcuref_xxx primitives to preserve atomicity.
Note: Use rcuref_inc api only if you need to use rcuref_inc_lf on the
refcounter atleast at one place. Mixing rcuref_inc and atomic_xxx api
might lead to races. rcuref_inc_lf() must be used in lockfree
RCU critical sections only.

902
Documentation/RCU/whatisRCU.txt Normal file
View file

@ -0,0 +1,902 @@
What is RCU?
RCU is a synchronization mechanism that was added to the Linux kernel
during the 2.5 development effort that is optimized for read-mostly
situations. Although RCU is actually quite simple once you understand it,
getting there can sometimes be a challenge. Part of the problem is that
most of the past descriptions of RCU have been written with the mistaken
assumption that there is "one true way" to describe RCU. Instead,
the experience has been that different people must take different paths
to arrive at an understanding of RCU. This document provides several
different paths, as follows:
1. RCU OVERVIEW
2. WHAT IS RCU'S CORE API?
3. WHAT ARE SOME EXAMPLE USES OF CORE RCU API?
4. WHAT IF MY UPDATING THREAD CANNOT BLOCK?
5. WHAT ARE SOME SIMPLE IMPLEMENTATIONS OF RCU?
6. ANALOGY WITH READER-WRITER LOCKING
7. FULL LIST OF RCU APIs
8. ANSWERS TO QUICK QUIZZES
People who prefer starting with a conceptual overview should focus on
Section 1, though most readers will profit by reading this section at
some point. People who prefer to start with an API that they can then
experiment with should focus on Section 2. People who prefer to start
with example uses should focus on Sections 3 and 4. People who need to
understand the RCU implementation should focus on Section 5, then dive
into the kernel source code. People who reason best by analogy should
focus on Section 6. Section 7 serves as an index to the docbook API
documentation, and Section 8 is the traditional answer key.
So, start with the section that makes the most sense to you and your
preferred method of learning. If you need to know everything about
everything, feel free to read the whole thing -- but if you are really
that type of person, you have perused the source code and will therefore
never need this document anyway. ;-)
1. RCU OVERVIEW
The basic idea behind RCU is to split updates into "removal" and
"reclamation" phases. The removal phase removes references to data items
within a data structure (possibly by replacing them with references to
new versions of these data items), and can run concurrently with readers.
The reason that it is safe to run the removal phase concurrently with
readers is the semantics of modern CPUs guarantee that readers will see
either the old or the new version of the data structure rather than a
partially updated reference. The reclamation phase does the work of reclaiming
(e.g., freeing) the data items removed from the data structure during the
removal phase. Because reclaiming data items can disrupt any readers
concurrently referencing those data items, the reclamation phase must
not start until readers no longer hold references to those data items.
Splitting the update into removal and reclamation phases permits the
updater to perform the removal phase immediately, and to defer the
reclamation phase until all readers active during the removal phase have
completed, either by blocking until they finish or by registering a
callback that is invoked after they finish. Only readers that are active
during the removal phase need be considered, because any reader starting
after the removal phase will be unable to gain a reference to the removed
data items, and therefore cannot be disrupted by the reclamation phase.
So the typical RCU update sequence goes something like the following:
a. Remove pointers to a data structure, so that subsequent
readers cannot gain a reference to it.
b. Wait for all previous readers to complete their RCU read-side
critical sections.
c. At this point, there cannot be any readers who hold references
to the data structure, so it now may safely be reclaimed
(e.g., kfree()d).
Step (b) above is the key idea underlying RCU's deferred destruction.
The ability to wait until all readers are done allows RCU readers to
use much lighter-weight synchronization, in some cases, absolutely no
synchronization at all. In contrast, in more conventional lock-based
schemes, readers must use heavy-weight synchronization in order to
prevent an updater from deleting the data structure out from under them.
This is because lock-based updaters typically update data items in place,
and must therefore exclude readers. In contrast, RCU-based updaters
typically take advantage of the fact that writes to single aligned
pointers are atomic on modern CPUs, allowing atomic insertion, removal,
and replacement of data items in a linked structure without disrupting
readers. Concurrent RCU readers can then continue accessing the old
versions, and can dispense with the atomic operations, memory barriers,
and communications cache misses that are so expensive on present-day
SMP computer systems, even in absence of lock contention.
In the three-step procedure shown above, the updater is performing both
the removal and the reclamation step, but it is often helpful for an
entirely different thread to do the reclamation, as is in fact the case
in the Linux kernel's directory-entry cache (dcache). Even if the same
thread performs both the update step (step (a) above) and the reclamation
step (step (c) above), it is often helpful to think of them separately.
For example, RCU readers and updaters need not communicate at all,
but RCU provides implicit low-overhead communication between readers
and reclaimers, namely, in step (b) above.
So how the heck can a reclaimer tell when a reader is done, given
that readers are not doing any sort of synchronization operations???
Read on to learn about how RCU's API makes this easy.
2. WHAT IS RCU'S CORE API?
The core RCU API is quite small:
a. rcu_read_lock()
b. rcu_read_unlock()
c. synchronize_rcu() / call_rcu()
d. rcu_assign_pointer()
e. rcu_dereference()
There are many other members of the RCU API, but the rest can be
expressed in terms of these five, though most implementations instead
express synchronize_rcu() in terms of the call_rcu() callback API.
The five core RCU APIs are described below, the other 18 will be enumerated
later. See the kernel docbook documentation for more info, or look directly
at the function header comments.
rcu_read_lock()
void rcu_read_lock(void);
Used by a reader to inform the reclaimer that the reader is
entering an RCU read-side critical section. It is illegal
to block while in an RCU read-side critical section, though
kernels built with CONFIG_PREEMPT_RCU can preempt RCU read-side
critical sections. Any RCU-protected data structure accessed
during an RCU read-side critical section is guaranteed to remain
unreclaimed for the full duration of that critical section.
Reference counts may be used in conjunction with RCU to maintain
longer-term references to data structures.
rcu_read_unlock()
void rcu_read_unlock(void);
Used by a reader to inform the reclaimer that the reader is
exiting an RCU read-side critical section. Note that RCU
read-side critical sections may be nested and/or overlapping.
synchronize_rcu()
void synchronize_rcu(void);
Marks the end of updater code and the beginning of reclaimer
code. It does this by blocking until all pre-existing RCU
read-side critical sections on all CPUs have completed.
Note that synchronize_rcu() will -not- necessarily wait for
any subsequent RCU read-side critical sections to complete.
For example, consider the following sequence of events:
CPU 0 CPU 1 CPU 2
----------------- ------------------------- ---------------
1. rcu_read_lock()
2. enters synchronize_rcu()
3. rcu_read_lock()
4. rcu_read_unlock()
5. exits synchronize_rcu()
6. rcu_read_unlock()
To reiterate, synchronize_rcu() waits only for ongoing RCU
read-side critical sections to complete, not necessarily for
any that begin after synchronize_rcu() is invoked.
Of course, synchronize_rcu() does not necessarily return
-immediately- after the last pre-existing RCU read-side critical
section completes. For one thing, there might well be scheduling
delays. For another thing, many RCU implementations process
requests in batches in order to improve efficiencies, which can
further delay synchronize_rcu().
Since synchronize_rcu() is the API that must figure out when
readers are done, its implementation is key to RCU. For RCU
to be useful in all but the most read-intensive situations,
synchronize_rcu()'s overhead must also be quite small.
The call_rcu() API is a callback form of synchronize_rcu(),
and is described in more detail in a later section. Instead of
blocking, it registers a function and argument which are invoked
after all ongoing RCU read-side critical sections have completed.
This callback variant is particularly useful in situations where
it is illegal to block.
rcu_assign_pointer()
typeof(p) rcu_assign_pointer(p, typeof(p) v);
Yes, rcu_assign_pointer() -is- implemented as a macro, though it
would be cool to be able to declare a function in this manner.
(Compiler experts will no doubt disagree.)
The updater uses this function to assign a new value to an
RCU-protected pointer, in order to safely communicate the change
in value from the updater to the reader. This function returns
the new value, and also executes any memory-barrier instructions
required for a given CPU architecture.
Perhaps more important, it serves to document which pointers
are protected by RCU. That said, rcu_assign_pointer() is most
frequently used indirectly, via the _rcu list-manipulation
primitives such as list_add_rcu().
rcu_dereference()
typeof(p) rcu_dereference(p);
Like rcu_assign_pointer(), rcu_dereference() must be implemented
as a macro.
The reader uses rcu_dereference() to fetch an RCU-protected
pointer, which returns a value that may then be safely
dereferenced. Note that rcu_deference() does not actually
dereference the pointer, instead, it protects the pointer for
later dereferencing. It also executes any needed memory-barrier
instructions for a given CPU architecture. Currently, only Alpha
needs memory barriers within rcu_dereference() -- on other CPUs,
it compiles to nothing, not even a compiler directive.
Common coding practice uses rcu_dereference() to copy an
RCU-protected pointer to a local variable, then dereferences
this local variable, for example as follows:
p = rcu_dereference(head.next);
return p->data;
However, in this case, one could just as easily combine these
into one statement:
return rcu_dereference(head.next)->data;
If you are going to be fetching multiple fields from the
RCU-protected structure, using the local variable is of
course preferred. Repeated rcu_dereference() calls look
ugly and incur unnecessary overhead on Alpha CPUs.
Note that the value returned by rcu_dereference() is valid
only within the enclosing RCU read-side critical section.
For example, the following is -not- legal:
rcu_read_lock();
p = rcu_dereference(head.next);
rcu_read_unlock();
x = p->address;
rcu_read_lock();
y = p->data;
rcu_read_unlock();
Holding a reference from one RCU read-side critical section
to another is just as illegal as holding a reference from
one lock-based critical section to another! Similarly,
using a reference outside of the critical section in which
it was acquired is just as illegal as doing so with normal
locking.
As with rcu_assign_pointer(), an important function of
rcu_dereference() is to document which pointers are protected
by RCU. And, again like rcu_assign_pointer(), rcu_dereference()
is typically used indirectly, via the _rcu list-manipulation
primitives, such as list_for_each_entry_rcu().
The following diagram shows how each API communicates among the
reader, updater, and reclaimer.
rcu_assign_pointer()
+--------+
+---------------------->| reader |---------+
| +--------+ |
| | |
| | | Protect:
| | | rcu_read_lock()
| | | rcu_read_unlock()
| rcu_dereference() | |
+---------+ | |
| updater |<---------------------+ |
+---------+ V
| +-----------+
+----------------------------------->| reclaimer |
+-----------+
Defer:
synchronize_rcu() & call_rcu()
The RCU infrastructure observes the time sequence of rcu_read_lock(),
rcu_read_unlock(), synchronize_rcu(), and call_rcu() invocations in
order to determine when (1) synchronize_rcu() invocations may return
to their callers and (2) call_rcu() callbacks may be invoked. Efficient
implementations of the RCU infrastructure make heavy use of batching in
order to amortize their overhead over many uses of the corresponding APIs.
There are no fewer than three RCU mechanisms in the Linux kernel; the
diagram above shows the first one, which is by far the most commonly used.
The rcu_dereference() and rcu_assign_pointer() primitives are used for
all three mechanisms, but different defer and protect primitives are
used as follows:
Defer Protect
a. synchronize_rcu() rcu_read_lock() / rcu_read_unlock()
call_rcu()
b. call_rcu_bh() rcu_read_lock_bh() / rcu_read_unlock_bh()
c. synchronize_sched() preempt_disable() / preempt_enable()
local_irq_save() / local_irq_restore()
hardirq enter / hardirq exit
NMI enter / NMI exit
These three mechanisms are used as follows:
a. RCU applied to normal data structures.
b. RCU applied to networking data structures that may be subjected
to remote denial-of-service attacks.
c. RCU applied to scheduler and interrupt/NMI-handler tasks.
Again, most uses will be of (a). The (b) and (c) cases are important
for specialized uses, but are relatively uncommon.
3. WHAT ARE SOME EXAMPLE USES OF CORE RCU API?
This section shows a simple use of the core RCU API to protect a
global pointer to a dynamically allocated structure. More typical
uses of RCU may be found in listRCU.txt, arrayRCU.txt, and NMI-RCU.txt.
struct foo {
int a;
char b;
long c;
};
DEFINE_SPINLOCK(foo_mutex);
struct foo *gbl_foo;
/*
* Create a new struct foo that is the same as the one currently
* pointed to by gbl_foo, except that field "a" is replaced
* with "new_a". Points gbl_foo to the new structure, and
* frees up the old structure after a grace period.
*
* Uses rcu_assign_pointer() to ensure that concurrent readers
* see the initialized version of the new structure.
*
* Uses synchronize_rcu() to ensure that any readers that might
* have references to the old structure complete before freeing
* the old structure.
*/
void foo_update_a(int new_a)
{
struct foo *new_fp;
struct foo *old_fp;
new_fp = kmalloc(sizeof(*fp), GFP_KERNEL);
spin_lock(&foo_mutex);
old_fp = gbl_foo;
*new_fp = *old_fp;
new_fp->a = new_a;
rcu_assign_pointer(gbl_foo, new_fp);
spin_unlock(&foo_mutex);
synchronize_rcu();
kfree(old_fp);
}
/*
* Return the value of field "a" of the current gbl_foo
* structure. Use rcu_read_lock() and rcu_read_unlock()
* to ensure that the structure does not get deleted out
* from under us, and use rcu_dereference() to ensure that
* we see the initialized version of the structure (important
* for DEC Alpha and for people reading the code).
*/
int foo_get_a(void)
{
int retval;
rcu_read_lock();
retval = rcu_dereference(gbl_foo)->a;
rcu_read_unlock();
return retval;
}
So, to sum up:
o Use rcu_read_lock() and rcu_read_unlock() to guard RCU
read-side critical sections.
o Within an RCU read-side critical section, use rcu_dereference()
to dereference RCU-protected pointers.
o Use some solid scheme (such as locks or semaphores) to
keep concurrent updates from interfering with each other.
o Use rcu_assign_pointer() to update an RCU-protected pointer.
This primitive protects concurrent readers from the updater,
-not- concurrent updates from each other! You therefore still
need to use locking (or something similar) to keep concurrent
rcu_assign_pointer() primitives from interfering with each other.
o Use synchronize_rcu() -after- removing a data element from an
RCU-protected data structure, but -before- reclaiming/freeing
the data element, in order to wait for the completion of all
RCU read-side critical sections that might be referencing that
data item.
See checklist.txt for additional rules to follow when using RCU.
4. WHAT IF MY UPDATING THREAD CANNOT BLOCK?
In the example above, foo_update_a() blocks until a grace period elapses.
This is quite simple, but in some cases one cannot afford to wait so
long -- there might be other high-priority work to be done.
In such cases, one uses call_rcu() rather than synchronize_rcu().
The call_rcu() API is as follows:
void call_rcu(struct rcu_head * head,
void (*func)(struct rcu_head *head));
This function invokes func(head) after a grace period has elapsed.
This invocation might happen from either softirq or process context,
so the function is not permitted to block. The foo struct needs to
have an rcu_head structure added, perhaps as follows:
struct foo {
int a;
char b;
long c;
struct rcu_head rcu;
};
The foo_update_a() function might then be written as follows:
/*
* Create a new struct foo that is the same as the one currently
* pointed to by gbl_foo, except that field "a" is replaced
* with "new_a". Points gbl_foo to the new structure, and
* frees up the old structure after a grace period.
*
* Uses rcu_assign_pointer() to ensure that concurrent readers
* see the initialized version of the new structure.
*
* Uses call_rcu() to ensure that any readers that might have
* references to the old structure complete before freeing the
* old structure.
*/
void foo_update_a(int new_a)
{
struct foo *new_fp;
struct foo *old_fp;
new_fp = kmalloc(sizeof(*fp), GFP_KERNEL);
spin_lock(&foo_mutex);
old_fp = gbl_foo;
*new_fp = *old_fp;
new_fp->a = new_a;
rcu_assign_pointer(gbl_foo, new_fp);
spin_unlock(&foo_mutex);
call_rcu(&old_fp->rcu, foo_reclaim);
}
The foo_reclaim() function might appear as follows:
void foo_reclaim(struct rcu_head *rp)
{
struct foo *fp = container_of(rp, struct foo, rcu);
kfree(fp);
}
The container_of() primitive is a macro that, given a pointer into a
struct, the type of the struct, and the pointed-to field within the
struct, returns a pointer to the beginning of the struct.
The use of call_rcu() permits the caller of foo_update_a() to
immediately regain control, without needing to worry further about the
old version of the newly updated element. It also clearly shows the
RCU distinction between updater, namely foo_update_a(), and reclaimer,
namely foo_reclaim().
The summary of advice is the same as for the previous section, except
that we are now using call_rcu() rather than synchronize_rcu():
o Use call_rcu() -after- removing a data element from an
RCU-protected data structure in order to register a callback
function that will be invoked after the completion of all RCU
read-side critical sections that might be referencing that
data item.
Again, see checklist.txt for additional rules governing the use of RCU.
5. WHAT ARE SOME SIMPLE IMPLEMENTATIONS OF RCU?
One of the nice things about RCU is that it has extremely simple "toy"
implementations that are a good first step towards understanding the
production-quality implementations in the Linux kernel. This section
presents two such "toy" implementations of RCU, one that is implemented
in terms of familiar locking primitives, and another that more closely
resembles "classic" RCU. Both are way too simple for real-world use,
lacking both functionality and performance. However, they are useful
in getting a feel for how RCU works. See kernel/rcupdate.c for a
production-quality implementation, and see:
http://www.rdrop.com/users/paulmck/RCU
for papers describing the Linux kernel RCU implementation. The OLS'01
and OLS'02 papers are a good introduction, and the dissertation provides
more details on the current implementation.
5A. "TOY" IMPLEMENTATION #1: LOCKING
This section presents a "toy" RCU implementation that is based on
familiar locking primitives. Its overhead makes it a non-starter for
real-life use, as does its lack of scalability. It is also unsuitable
for realtime use, since it allows scheduling latency to "bleed" from
one read-side critical section to another.
However, it is probably the easiest implementation to relate to, so is
a good starting point.
It is extremely simple:
static DEFINE_RWLOCK(rcu_gp_mutex);
void rcu_read_lock(void)
{
read_lock(&rcu_gp_mutex);
}
void rcu_read_unlock(void)
{
read_unlock(&rcu_gp_mutex);
}
void synchronize_rcu(void)
{
write_lock(&rcu_gp_mutex);
write_unlock(&rcu_gp_mutex);
}
[You can ignore rcu_assign_pointer() and rcu_dereference() without
missing much. But here they are anyway. And whatever you do, don't
forget about them when submitting patches making use of RCU!]
#define rcu_assign_pointer(p, v) ({ \
smp_wmb(); \
(p) = (v); \
})
#define rcu_dereference(p) ({ \
typeof(p) _________p1 = p; \
smp_read_barrier_depends(); \
(_________p1); \
})
The rcu_read_lock() and rcu_read_unlock() primitive read-acquire
and release a global reader-writer lock. The synchronize_rcu()
primitive write-acquires this same lock, then immediately releases
it. This means that once synchronize_rcu() exits, all RCU read-side
critical sections that were in progress before synchonize_rcu() was
called are guaranteed to have completed -- there is no way that
synchronize_rcu() would have been able to write-acquire the lock
otherwise.
It is possible to nest rcu_read_lock(), since reader-writer locks may
be recursively acquired. Note also that rcu_read_lock() is immune
from deadlock (an important property of RCU). The reason for this is
that the only thing that can block rcu_read_lock() is a synchronize_rcu().
But synchronize_rcu() does not acquire any locks while holding rcu_gp_mutex,
so there can be no deadlock cycle.
Quick Quiz #1: Why is this argument naive? How could a deadlock
occur when using this algorithm in a real-world Linux
kernel? How could this deadlock be avoided?
5B. "TOY" EXAMPLE #2: CLASSIC RCU
This section presents a "toy" RCU implementation that is based on
"classic RCU". It is also short on performance (but only for updates) and
on features such as hotplug CPU and the ability to run in CONFIG_PREEMPT
kernels. The definitions of rcu_dereference() and rcu_assign_pointer()
are the same as those shown in the preceding section, so they are omitted.
void rcu_read_lock(void) { }
void rcu_read_unlock(void) { }
void synchronize_rcu(void)
{
int cpu;
for_each_cpu(cpu)
run_on(cpu);
}
Note that rcu_read_lock() and rcu_read_unlock() do absolutely nothing.
This is the great strength of classic RCU in a non-preemptive kernel:
read-side overhead is precisely zero, at least on non-Alpha CPUs.
And there is absolutely no way that rcu_read_lock() can possibly
participate in a deadlock cycle!
The implementation of synchronize_rcu() simply schedules itself on each
CPU in turn. The run_on() primitive can be implemented straightforwardly
in terms of the sched_setaffinity() primitive. Of course, a somewhat less
"toy" implementation would restore the affinity upon completion rather
than just leaving all tasks running on the last CPU, but when I said
"toy", I meant -toy-!
So how the heck is this supposed to work???
Remember that it is illegal to block while in an RCU read-side critical
section. Therefore, if a given CPU executes a context switch, we know
that it must have completed all preceding RCU read-side critical sections.
Once -all- CPUs have executed a context switch, then -all- preceding
RCU read-side critical sections will have completed.
So, suppose that we remove a data item from its structure and then invoke
synchronize_rcu(). Once synchronize_rcu() returns, we are guaranteed
that there are no RCU read-side critical sections holding a reference
to that data item, so we can safely reclaim it.
Quick Quiz #2: Give an example where Classic RCU's read-side
overhead is -negative-.
Quick Quiz #3: If it is illegal to block in an RCU read-side
critical section, what the heck do you do in
PREEMPT_RT, where normal spinlocks can block???
6. ANALOGY WITH READER-WRITER LOCKING
Although RCU can be used in many different ways, a very common use of
RCU is analogous to reader-writer locking. The following unified
diff shows how closely related RCU and reader-writer locking can be.
@@ -13,15 +14,15 @@
struct list_head *lp;
struct el *p;
- read_lock();
- list_for_each_entry(p, head, lp) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(p, head, lp) {
if (p->key == key) {
*result = p->data;
- read_unlock();
+ rcu_read_unlock();
return 1;
}
}
- read_unlock();
+ rcu_read_unlock();
return 0;
}
@@ -29,15 +30,16 @@
{
struct el *p;
- write_lock(&listmutex);
+ spin_lock(&listmutex);
list_for_each_entry(p, head, lp) {
if (p->key == key) {
list_del(&p->list);
- write_unlock(&listmutex);
+ spin_unlock(&listmutex);
+ synchronize_rcu();
kfree(p);
return 1;
}
}
- write_unlock(&listmutex);
+ spin_unlock(&listmutex);
return 0;
}
Or, for those who prefer a side-by-side listing:
1 struct el { 1 struct el {
2 struct list_head list; 2 struct list_head list;
3 long key; 3 long key;
4 spinlock_t mutex; 4 spinlock_t mutex;
5 int data; 5 int data;
6 /* Other data fields */ 6 /* Other data fields */
7 }; 7 };
8 spinlock_t listmutex; 8 spinlock_t listmutex;
9 struct el head; 9 struct el head;
1 int search(long key, int *result) 1 int search(long key, int *result)
2 { 2 {
3 struct list_head *lp; 3 struct list_head *lp;
4 struct el *p; 4 struct el *p;
5 5
6 read_lock(); 6 rcu_read_lock();
7 list_for_each_entry(p, head, lp) { 7 list_for_each_entry_rcu(p, head, lp) {
8 if (p->key == key) { 8 if (p->key == key) {
9 *result = p->data; 9 *result = p->data;
10 read_unlock(); 10 rcu_read_unlock();
11 return 1; 11 return 1;
12 } 12 }
13 } 13 }
14 read_unlock(); 14 rcu_read_unlock();
15 return 0; 15 return 0;
16 } 16 }
1 int delete(long key) 1 int delete(long key)
2 { 2 {
3 struct el *p; 3 struct el *p;
4 4
5 write_lock(&listmutex); 5 spin_lock(&listmutex);
6 list_for_each_entry(p, head, lp) { 6 list_for_each_entry(p, head, lp) {
7 if (p->key == key) { 7 if (p->key == key) {
8 list_del(&p->list); 8 list_del(&p->list);
9 write_unlock(&listmutex); 9 spin_unlock(&listmutex);
10 synchronize_rcu();
10 kfree(p); 11 kfree(p);
11 return 1; 12 return 1;
12 } 13 }
13 } 14 }
14 write_unlock(&listmutex); 15 spin_unlock(&listmutex);
15 return 0; 16 return 0;
16 } 17 }
Either way, the differences are quite small. Read-side locking moves
to rcu_read_lock() and rcu_read_unlock, update-side locking moves from
from a reader-writer lock to a simple spinlock, and a synchronize_rcu()
precedes the kfree().
However, there is one potential catch: the read-side and update-side
critical sections can now run concurrently. In many cases, this will
not be a problem, but it is necessary to check carefully regardless.
For example, if multiple independent list updates must be seen as
a single atomic update, converting to RCU will require special care.
Also, the presence of synchronize_rcu() means that the RCU version of
delete() can now block. If this is a problem, there is a callback-based
mechanism that never blocks, namely call_rcu(), that can be used in
place of synchronize_rcu().
7. FULL LIST OF RCU APIs
The RCU APIs are documented in docbook-format header comments in the
Linux-kernel source code, but it helps to have a full list of the
APIs, since there does not appear to be a way to categorize them
in docbook. Here is the list, by category.
Markers for RCU read-side critical sections:
rcu_read_lock
rcu_read_unlock
rcu_read_lock_bh
rcu_read_unlock_bh
RCU pointer/list traversal:
rcu_dereference
list_for_each_rcu (to be deprecated in favor of
list_for_each_entry_rcu)
list_for_each_safe_rcu (deprecated, not used)
list_for_each_entry_rcu
list_for_each_continue_rcu (to be deprecated in favor of new
list_for_each_entry_continue_rcu)
hlist_for_each_rcu (to be deprecated in favor of
hlist_for_each_entry_rcu)
hlist_for_each_entry_rcu
RCU pointer update:
rcu_assign_pointer
list_add_rcu
list_add_tail_rcu
list_del_rcu
list_replace_rcu
hlist_del_rcu
hlist_add_head_rcu
RCU grace period:
synchronize_kernel (deprecated)
synchronize_net
synchronize_sched
synchronize_rcu
call_rcu
call_rcu_bh
See the comment headers in the source code (or the docbook generated
from them) for more information.
8. ANSWERS TO QUICK QUIZZES
Quick Quiz #1: Why is this argument naive? How could a deadlock
occur when using this algorithm in a real-world Linux
kernel? [Referring to the lock-based "toy" RCU
algorithm.]
Answer: Consider the following sequence of events:
1. CPU 0 acquires some unrelated lock, call it
"problematic_lock".
2. CPU 1 enters synchronize_rcu(), write-acquiring
rcu_gp_mutex.
3. CPU 0 enters rcu_read_lock(), but must wait
because CPU 1 holds rcu_gp_mutex.
4. CPU 1 is interrupted, and the irq handler
attempts to acquire problematic_lock.
The system is now deadlocked.
One way to avoid this deadlock is to use an approach like
that of CONFIG_PREEMPT_RT, where all normal spinlocks
become blocking locks, and all irq handlers execute in
the context of special tasks. In this case, in step 4
above, the irq handler would block, allowing CPU 1 to
release rcu_gp_mutex, avoiding the deadlock.
Even in the absence of deadlock, this RCU implementation
allows latency to "bleed" from readers to other
readers through synchronize_rcu(). To see this,
consider task A in an RCU read-side critical section
(thus read-holding rcu_gp_mutex), task B blocked
attempting to write-acquire rcu_gp_mutex, and
task C blocked in rcu_read_lock() attempting to
read_acquire rcu_gp_mutex. Task A's RCU read-side
latency is holding up task C, albeit indirectly via
task B.
Realtime RCU implementations therefore use a counter-based
approach where tasks in RCU read-side critical sections
cannot be blocked by tasks executing synchronize_rcu().
Quick Quiz #2: Give an example where Classic RCU's read-side
overhead is -negative-.
Answer: Imagine a single-CPU system with a non-CONFIG_PREEMPT
kernel where a routing table is used by process-context
code, but can be updated by irq-context code (for example,
by an "ICMP REDIRECT" packet). The usual way of handling
this would be to have the process-context code disable
interrupts while searching the routing table. Use of
RCU allows such interrupt-disabling to be dispensed with.
Thus, without RCU, you pay the cost of disabling interrupts,
and with RCU you don't.
One can argue that the overhead of RCU in this
case is negative with respect to the single-CPU
interrupt-disabling approach. Others might argue that
the overhead of RCU is merely zero, and that replacing
the positive overhead of the interrupt-disabling scheme
with the zero-overhead RCU scheme does not constitute
negative overhead.
In real life, of course, things are more complex. But
even the theoretical possibility of negative overhead for
a synchronization primitive is a bit unexpected. ;-)
Quick Quiz #3: If it is illegal to block in an RCU read-side
critical section, what the heck do you do in
PREEMPT_RT, where normal spinlocks can block???
Answer: Just as PREEMPT_RT permits preemption of spinlock
critical sections, it permits preemption of RCU
read-side critical sections. It also permits
spinlocks blocking while in RCU read-side critical
sections.
Why the apparent inconsistency? Because it is it
possible to use priority boosting to keep the RCU
grace periods short if need be (for example, if running
short of memory). In contrast, if blocking waiting
for (say) network reception, there is no way to know
what should be boosted. Especially given that the
process we need to boost might well be a human being
who just went out for a pizza or something. And although
a computer-operated cattle prod might arouse serious
interest, it might also provoke serious objections.
Besides, how does the computer know what pizza parlor
the human being went to???
ACKNOWLEDGEMENTS
My thanks to the people who helped make this human-readable, including
Jon Walpole, Josh Triplett, Serge Hallyn, and Suzanne Wood.
For more information, see http://www.rdrop.com/users/paulmck/RCU.

439
Documentation/applying-patches.txt Normal file
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@ -0,0 +1,439 @@
Applying Patches To The Linux Kernel
------------------------------------
(Written by Jesper Juhl, August 2005)
A frequently asked question on the Linux Kernel Mailing List is how to apply
a patch to the kernel or, more specifically, what base kernel a patch for
one of the many trees/branches should be applied to. Hopefully this document
will explain this to you.
In addition to explaining how to apply and revert patches, a brief
description of the different kernel trees (and examples of how to apply
their specific patches) is also provided.
What is a patch?
---
A patch is a small text document containing a delta of changes between two
different versions of a source tree. Patches are created with the `diff'
program.
To correctly apply a patch you need to know what base it was generated from
and what new version the patch will change the source tree into. These
should both be present in the patch file metadata or be possible to deduce
from the filename.
How do I apply or revert a patch?
---
You apply a patch with the `patch' program. The patch program reads a diff
(or patch) file and makes the changes to the source tree described in it.
Patches for the Linux kernel are generated relative to the parent directory
holding the kernel source dir.
This means that paths to files inside the patch file contain the name of the
kernel source directories it was generated against (or some other directory
names like "a/" and "b/").
Since this is unlikely to match the name of the kernel source dir on your
local machine (but is often useful info to see what version an otherwise
unlabeled patch was generated against) you should change into your kernel
source directory and then strip the first element of the path from filenames
in the patch file when applying it (the -p1 argument to `patch' does this).
To revert a previously applied patch, use the -R argument to patch.
So, if you applied a patch like this:
patch -p1 < ../patch-x.y.z
You can revert (undo) it like this:
patch -R -p1 < ../patch-x.y.z
How do I feed a patch/diff file to `patch'?
---
This (as usual with Linux and other UNIX like operating systems) can be
done in several different ways.
In all the examples below I feed the file (in uncompressed form) to patch
via stdin using the following syntax:
patch -p1 < path/to/patch-x.y.z
If you just want to be able to follow the examples below and don't want to
know of more than one way to use patch, then you can stop reading this
section here.
Patch can also get the name of the file to use via the -i argument, like
this:
patch -p1 -i path/to/patch-x.y.z
If your patch file is compressed with gzip or bzip2 and you don't want to
uncompress it before applying it, then you can feed it to patch like this
instead:
zcat path/to/patch-x.y.z.gz | patch -p1
bzcat path/to/patch-x.y.z.bz2 | patch -p1
If you wish to uncompress the patch file by hand first before applying it
(what I assume you've done in the examples below), then you simply run
gunzip or bunzip2 on the file - like this:
gunzip patch-x.y.z.gz
bunzip2 patch-x.y.z.bz2
Which will leave you with a plain text patch-x.y.z file that you can feed to
patch via stdin or the -i argument, as you prefer.
A few other nice arguments for patch are -s which causes patch to be silent
except for errors which is nice to prevent errors from scrolling out of the
screen too fast, and --dry-run which causes patch to just print a listing of
what would happen, but doesn't actually make any changes. Finally --verbose
tells patch to print more information about the work being done.
Common errors when patching
---
When patch applies a patch file it attempts to verify the sanity of the
file in different ways.
Checking that the file looks like a valid patch file, checking the code
around the bits being modified matches the context provided in the patch are
just two of the basic sanity checks patch does.
If patch encounters something that doesn't look quite right it has two
options. It can either refuse to apply the changes and abort or it can try
to find a way to make the patch apply with a few minor changes.
One example of something that's not 'quite right' that patch will attempt to
fix up is if all the context matches, the lines being changed match, but the
line numbers are different. This can happen, for example, if the patch makes
a change in the middle of the file but for some reasons a few lines have
been added or removed near the beginning of the file. In that case
everything looks good it has just moved up or down a bit, and patch will
usually adjust the line numbers and apply the patch.
Whenever patch applies a patch that it had to modify a bit to make it fit
it'll tell you about it by saying the patch applied with 'fuzz'.
You should be wary of such changes since even though patch probably got it
right it doesn't /always/ get it right, and the result will sometimes be
wrong.
When patch encounters a change that it can't fix up with fuzz it rejects it
outright and leaves a file with a .rej extension (a reject file). You can
read this file to see exactely what change couldn't be applied, so you can
go fix it up by hand if you wish.
If you don't have any third party patches applied to your kernel source, but
only patches from kernel.org and you apply the patches in the correct order,
and have made no modifications yourself to the source files, then you should
never see a fuzz or reject message from patch. If you do see such messages
anyway, then there's a high risk that either your local source tree or the
patch file is corrupted in some way. In that case you should probably try
redownloading the patch and if things are still not OK then you'd be advised
to start with a fresh tree downloaded in full from kernel.org.
Let's look a bit more at some of the messages patch can produce.
If patch stops and presents a "File to patch:" prompt, then patch could not
find a file to be patched. Most likely you forgot to specify -p1 or you are
in the wrong directory. Less often, you'll find patches that need to be
applied with -p0 instead of -p1 (reading the patch file should reveal if
this is the case - if so, then this is an error by the person who created
the patch but is not fatal).
If you get "Hunk #2 succeeded at 1887 with fuzz 2 (offset 7 lines)." or a
message similar to that, then it means that patch had to adjust the location
of the change (in this example it needed to move 7 lines from where it
expected to make the change to make it fit).
The resulting file may or may not be OK, depending on the reason the file
was different than expected.
This often happens if you try to apply a patch that was generated against a
different kernel version than the one you are trying to patch.
If you get a message like "Hunk #3 FAILED at 2387.", then it means that the
patch could not be applied correctly and the patch program was unable to
fuzz its way through. This will generate a .rej file with the change that
caused the patch to fail and also a .orig file showing you the original
content that couldn't be changed.
If you get "Reversed (or previously applied) patch detected! Assume -R? [n]"
then patch detected that the change contained in the patch seems to have
already been made.
If you actually did apply this patch previously and you just re-applied it
in error, then just say [n]o and abort this patch. If you applied this patch
previously and actually intended to revert it, but forgot to specify -R,
then you can say [y]es here to make patch revert it for you.
This can also happen if the creator of the patch reversed the source and
destination directories when creating the patch, and in that case reverting
the patch will in fact apply it.
A message similar to "patch: **** unexpected end of file in patch" or "patch
unexpectedly ends in middle of line" means that patch could make no sense of
the file you fed to it. Either your download is broken or you tried to feed
patch a compressed patch file without uncompressing it first.
As I already mentioned above, these errors should never happen if you apply
a patch from kernel.org to the correct version of an unmodified source tree.
So if you get these errors with kernel.org patches then you should probably
assume that either your patch file or your tree is broken and I'd advice you
to start over with a fresh download of a full kernel tree and the patch you
wish to apply.
Are there any alternatives to `patch'?
---
Yes there are alternatives. You can use the `interdiff' program
(http://cyberelk.net/tim/patchutils/) to generate a patch representing the
differences between two patches and then apply the result.
This will let you move from something like 2.6.12.2 to 2.6.12.3 in a single
step. The -z flag to interdiff will even let you feed it patches in gzip or
bzip2 compressed form directly without the use of zcat or bzcat or manual
decompression.
Here's how you'd go from 2.6.12.2 to 2.6.12.3 in a single step:
interdiff -z ../patch-2.6.12.2.bz2 ../patch-2.6.12.3.gz | patch -p1
Although interdiff may save you a step or two you are generally advised to
do the additional steps since interdiff can get things wrong in some cases.
Another alternative is `ketchup', which is a python script for automatic
downloading and applying of patches (http://www.selenic.com/ketchup/).
Other nice tools are diffstat which shows a summary of changes made by a
patch, lsdiff which displays a short listing of affected files in a patch
file, along with (optionally) the line numbers of the start of each patch
and grepdiff which displays a list of the files modified by a patch where
the patch contains a given regular expression.
Where can I download the patches?
---
The patches are available at http://kernel.org/
Most recent patches are linked from the front page, but they also have
specific homes.
The 2.6.x.y (-stable) and 2.6.x patches live at
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/
The -rc patches live at
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/testing/
The -git patches live at
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/snapshots/
The -mm kernels live at
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/
In place of ftp.kernel.org you can use ftp.cc.kernel.org, where cc is a
country code. This way you'll be downloading from a mirror site that's most
likely geographically closer to you, resulting in faster downloads for you,
less bandwidth used globally and less load on the main kernel.org servers -
these are good things, do use mirrors when possible.
The 2.6.x kernels
---
These are the base stable releases released by Linus. The highest numbered
release is the most recent.
If regressions or other serious flaws are found then a -stable fix patch
will be released (see below) on top of this base. Once a new 2.6.x base
kernel is released, a patch is made available that is a delta between the
previous 2.6.x kernel and the new one.
To apply a patch moving from 2.6.11 to 2.6.12 you'd do the following (note
that such patches do *NOT* apply on top of 2.6.x.y kernels but on top of the
base 2.6.x kernel - if you need to move from 2.6.x.y to 2.6.x+1 you need to
first revert the 2.6.x.y patch).
Here are some examples:
# moving from 2.6.11 to 2.6.12
$ cd ~/linux-2.6.11 # change to kernel source dir
$ patch -p1 < ../patch-2.6.12 # apply the 2.6.12 patch
$ cd ..
$ mv linux-2.6.11 linux-2.6.12 # rename source dir
# moving from 2.6.11.1 to 2.6.12
$ cd ~/linux-2.6.11.1 # change to kernel source dir
$ patch -p1 -R < ../patch-2.6.11.1 # revert the 2.6.11.1 patch
# source dir is now 2.6.11
$ patch -p1 < ../patch-2.6.12 # apply new 2.6.12 patch
$ cd ..
$ mv linux-2.6.11.1 inux-2.6.12 # rename source dir
The 2.6.x.y kernels
---
Kernels with 4 digit versions are -stable kernels. They contain small(ish)
critical fixes for security problems or significant regressions discovered
in a given 2.6.x kernel.
This is the recommended branch for users who want the most recent stable
kernel and are not interested in helping test development/experimental
versions.
If no 2.6.x.y kernel is available, then the highest numbered 2.6.x kernel is
the current stable kernel.
These patches are not incremental, meaning that for example the 2.6.12.3
patch does not apply on top of the 2.6.12.2 kernel source, but rather on top
of the base 2.6.12 kernel source.
So, in order to apply the 2.6.12.3 patch to your existing 2.6.12.2 kernel
source you have to first back out the 2.6.12.2 patch (so you are left with a
base 2.6.12 kernel source) and then apply the new 2.6.12.3 patch.
Here's a small example:
$ cd ~/linux-2.6.12.2 # change into the kernel source dir
$ patch -p1 -R < ../patch-2.6.12.2 # revert the 2.6.12.2 patch
$ patch -p1 < ../patch-2.6.12.3 # apply the new 2.6.12.3 patch
$ cd ..
$ mv linux-2.6.12.2 linux-2.6.12.3 # rename the kernel source dir
The -rc kernels
---
These are release-candidate kernels. These are development kernels released
by Linus whenever he deems the current git (the kernel's source management
tool) tree to be in a reasonably sane state adequate for testing.
These kernels are not stable and you should expect occasional breakage if
you intend to run them. This is however the most stable of the main
development branches and is also what will eventually turn into the next
stable kernel, so it is important that it be tested by as many people as
possible.
This is a good branch to run for people who want to help out testing
development kernels but do not want to run some of the really experimental
stuff (such people should see the sections about -git and -mm kernels below).
The -rc patches are not incremental, they apply to a base 2.6.x kernel, just
like the 2.6.x.y patches described above. The kernel version before the -rcN
suffix denotes the version of the kernel that this -rc kernel will eventually
turn into.
So, 2.6.13-rc5 means that this is the fifth release candidate for the 2.6.13
kernel and the patch should be applied on top of the 2.6.12 kernel source.
Here are 3 examples of how to apply these patches:
# first an example of moving from 2.6.12 to 2.6.13-rc3
$ cd ~/linux-2.6.12 # change into the 2.6.12 source dir
$ patch -p1 < ../patch-2.6.13-rc3 # apply the 2.6.13-rc3 patch
$ cd ..
$ mv linux-2.6.12 linux-2.6.13-rc3 # rename the source dir
# now let's move from 2.6.13-rc3 to 2.6.13-rc5
$ cd ~/linux-2.6.13-rc3 # change into the 2.6.13-rc3 dir
$ patch -p1 -R < ../patch-2.6.13-rc3 # revert the 2.6.13-rc3 patch
$ patch -p1 < ../patch-2.6.13-rc5 # apply the new 2.6.13-rc5 patch
$ cd ..
$ mv linux-2.6.13-rc3 linux-2.6.13-rc5 # rename the source dir
# finally let's try and move from 2.6.12.3 to 2.6.13-rc5
$ cd ~/linux-2.6.12.3 # change to the kernel source dir
$ patch -p1 -R < ../patch-2.6.12.3 # revert the 2.6.12.3 patch
$ patch -p1 < ../patch-2.6.13-rc5 # apply new 2.6.13-rc5 patch
$ cd ..
$ mv linux-2.6.12.3 linux-2.6.13-rc5 # rename the kernel source dir
The -git kernels
---
These are daily snapshots of Linus' kernel tree (managed in a git
repository, hence the name).
These patches are usually released daily and represent the current state of
Linus' tree. They are more experimental than -rc kernels since they are
generated automatically without even a cursory glance to see if they are
sane.
-git patches are not incremental and apply either to a base 2.6.x kernel or
a base 2.6.x-rc kernel - you can see which from their name.
A patch named 2.6.12-git1 applies to the 2.6.12 kernel source and a patch
named 2.6.13-rc3-git2 applies to the source of the 2.6.13-rc3 kernel.
Here are some examples of how to apply these patches:
# moving from 2.6.12 to 2.6.12-git1
$ cd ~/linux-2.6.12 # change to the kernel source dir
$ patch -p1 < ../patch-2.6.12-git1 # apply the 2.6.12-git1 patch
$ cd ..
$ mv linux-2.6.12 linux-2.6.12-git1 # rename the kernel source dir
# moving from 2.6.12-git1 to 2.6.13-rc2-git3
$ cd ~/linux-2.6.12-git1 # change to the kernel source dir
$ patch -p1 -R < ../patch-2.6.12-git1 # revert the 2.6.12-git1 patch
# we now have a 2.6.12 kernel
$ patch -p1 < ../patch-2.6.13-rc2 # apply the 2.6.13-rc2 patch
# the kernel is now 2.6.13-rc2
$ patch -p1 < ../patch-2.6.13-rc2-git3 # apply the 2.6.13-rc2-git3 patch
# the kernel is now 2.6.13-rc2-git3
$ cd ..
$ mv linux-2.6.12-git1 linux-2.6.13-rc2-git3 # rename source dir
The -mm kernels
---
These are experimental kernels released by Andrew Morton.
The -mm tree serves as a sort of proving ground for new features and other
experimental patches.
Once a patch has proved its worth in -mm for a while Andrew pushes it on to
Linus for inclusion in mainline.
Although it's encouraged that patches flow to Linus via the -mm tree, this
is not always enforced.
Subsystem maintainers (or individuals) sometimes push their patches directly
to Linus, even though (or after) they have been merged and tested in -mm (or
sometimes even without prior testing in -mm).
You should generally strive to get your patches into mainline via -mm to
ensure maximum testing.
This branch is in constant flux and contains many experimental features, a
lot of debugging patches not appropriate for mainline etc and is the most
experimental of the branches described in this document.
These kernels are not appropriate for use on systems that are supposed to be
stable and they are more risky to run than any of the other branches (make
sure you have up-to-date backups - that goes for any experimental kernel but
even more so for -mm kernels).
These kernels in addition to all the other experimental patches they contain
usually also contain any changes in the mainline -git kernels available at
the time of release.
Testing of -mm kernels is greatly appreciated since the whole point of the
tree is to weed out regressions, crashes, data corruption bugs, build
breakage (and any other bug in general) before changes are merged into the
more stable mainline Linus tree.
But testers of -mm should be aware that breakage in this tree is more common
than in any other tree.
The -mm kernels are not released on a fixed schedule, but usually a few -mm
kernels are released in between each -rc kernel (1 to 3 is common).
The -mm kernels apply to either a base 2.6.x kernel (when no -rc kernels
have been released yet) or to a Linus -rc kernel.
Here are some examples of applying the -mm patches:
# moving from 2.6.12 to 2.6.12-mm1
$ cd ~/linux-2.6.12 # change to the 2.6.12 source dir
$ patch -p1 < ../2.6.12-mm1 # apply the 2.6.12-mm1 patch
$ cd ..
$ mv linux-2.6.12 linux-2.6.12-mm1 # rename the source appropriately
# moving from 2.6.12-mm1 to 2.6.13-rc3-mm3
$ cd ~/linux-2.6.12-mm1
$ patch -p1 -R < ../2.6.12-mm1 # revert the 2.6.12-mm1 patch
# we now have a 2.6.12 source
$ patch -p1 < ../patch-2.6.13-rc3 # apply the 2.6.13-rc3 patch
# we now have a 2.6.13-rc3 source
$ patch -p1 < ../2.6.13-rc3-mm3 # apply the 2.6.13-rc3-mm3 patch
$ cd ..
$ mv linux-2.6.12-mm1 linux-2.6.13-rc3-mm3 # rename the source dir
This concludes this list of explanations of the various kernel trees and I
hope you are now crystal clear on how to apply the various patches and help
testing the kernel.

2
Documentation/cpu-freq/cpufreq-stats.txt
View file

@ -36,7 +36,7 @@ cpufreq stats provides following statistics (explained in detail below).
All the statistics will be from the time the stats driver has been inserted
to the time when a read of a particular statistic is done. Obviously, stats
driver will not have any information about the the frequcny transitions before
driver will not have any information about the frequency transitions before
the stats driver insertion.
--------------------------------------------------------------------------------

2
Documentation/cpusets.txt
View file

@ -277,7 +277,7 @@ rewritten to the 'tasks' file of its cpuset. This is done to avoid
impacting the scheduler code in the kernel with a check for changes
in a tasks processor placement.
There is an exception to the above. If hotplug funtionality is used
There is an exception to the above. If hotplug functionality is used
to remove all the CPUs that are currently assigned to a cpuset,
then the kernel will automatically update the cpus_allowed of all
tasks attached to CPUs in that cpuset to allow all CPUs. When memory

2
Documentation/crypto/descore-readme.txt
View file

@ -1,4 +1,4 @@
Below is the orginal README file from the descore.shar package.
Below is the original README file from the descore.shar package.
------------------------------------------------------------------------------
des - fast & portable DES encryption & decryption.

97
Documentation/dvb/bt8xx.txt
View file

@ -1,55 +1,74 @@
How to get the Nebula Electronics DigiTV, Pinnacle PCTV Sat, Twinhan DST + clones working
=========================================================================================
How to get the Nebula, PCTV and Twinhan DST cards working
=========================================================
1) General information
======================
This class of cards has a bt878a as the PCI interface, and
require the bttv driver.
This class of cards has a bt878a chip as the PCI interface.
The different card drivers require the bttv driver to provide the means
to access the i2c bus and the gpio pins of the bt8xx chipset.
Please pay close attention to the warning about the bttv module
options below for the DST card.
2) Compilation rules for Kernel >= 2.6.12
=========================================
1) General informations
=======================
Enable the following options:
These drivers require the bttv driver to provide the means to access
the i2c bus and the gpio pins of the bt8xx chipset.
Because of this, you need to enable
"Device drivers" => "Multimedia devices"
=> "Video For Linux" => "BT848 Video For Linux"
"Device drivers" => "Multimedia devices" => "Digital Video Broadcasting Devices"
=> "DVB for Linux" "DVB Core Support" "BT8xx based PCI cards"
=> "Video For Linux" => "BT848 Video For Linux"
3) Loading Modules, described by two approaches
===============================================
Furthermore you need to enable
"Device drivers" => "Multimedia devices" => "Digital Video Broadcasting Devices"
=> "DVB for Linux" "DVB Core Support" "BT8xx based PCI cards"
2) Loading Modules
==================
In general you need to load the bttv driver, which will handle the gpio and
i2c communication for us, plus the common dvb-bt8xx device driver,
which is called the backend.
The frontends for Nebula DigiTV (nxt6000), Pinnacle PCTV Sat (cx24110),
TwinHan DST + clones (dst and dst-ca) are loaded automatically by the backend.
For further details about TwinHan DST + clones see /Documentation/dvb/ci.txt.
i2c communication for us, plus the common dvb-bt8xx device driver.
The frontends for Nebula (nxt6000), Pinnacle PCTV (cx24110) and
TwinHan (dst) are loaded automatically by the dvb-bt8xx device driver.
3a) The manual approach
-----------------------
Loading modules:
modprobe bttv
modprobe dvb-bt8xx
Unloading modules:
modprobe -r dvb-bt8xx
modprobe -r bttv
3b) The automatic approach
3a) Nebula / Pinnacle PCTV
--------------------------
If not already done by installation, place a line either in
/etc/modules.conf or in /etc/modprobe.conf containing this text:
alias char-major-81 bttv
$ modprobe bttv (normally bttv is being loaded automatically by kmod)
$ modprobe dvb-bt8xx (or just place dvb-bt8xx in /etc/modules for automatic loading)
Then place a line in /etc/modules containing this text:
dvb-bt8xx
Reboot your system and have fun!
3b) TwinHan and Clones
--------------------------
$ modprobe bttv i2c_hw=1 card=0x71
$ modprobe dvb-bt8xx
$ modprobe dst
The value 0x71 will override the PCI type detection for dvb-bt8xx,
which is necessary for TwinHan cards.
If you're having an older card (blue color circuit) and card=0x71 locks
your machine, try using 0x68, too. If that does not work, ask on the
mailing list.
The DST module takes a couple of useful parameters.
verbose takes values 0 to 4. These values control the verbosity level,
and can be used to debug also.
verbose=0 means complete disabling of messages
1 only error messages are displayed
2 notifications are also displayed
3 informational messages are also displayed
4 debug setting
dst_addons takes values 0 and 0x20. A value of 0 means it is a FTA card.
0x20 means it has a Conditional Access slot.
The autodected values are determined bythe cards 'response
string' which you can see in your logs e.g.
dst_get_device_id: Recognise [DSTMCI]
--
Authors: Richard Walker, Jamie Honan, Michael Hunold, Manu Abraham, Uwe Bugla
Authors: Richard Walker, Jamie Honan, Michael Hunold, Manu Abraham

9
Documentation/dvb/ci.txt
View file

@ -23,7 +23,6 @@ This application requires the following to function properly as of now.
eg: $ szap -c channels.conf -r "TMC" -x
(b) a channels.conf containing a valid PMT PID
eg: TMC:11996:h:0:27500:278:512:650:321
here 278 is a valid PMT PID. the rest of the values are the
@ -31,13 +30,7 @@ This application requires the following to function properly as of now.
(c) after running a szap, you have to run ca_zap, for the
descrambler to function,
eg: $ ca_zap patched_channels.conf "TMC"
The patched means a patch to apply to scan, such that scan can
generate a channels.conf_with pmt, which has this PMT PID info
(NOTE: szap cannot use this channels.conf with the PMT_PID)
eg: $ ca_zap channels.conf "TMC"
(d) Hopeflly Enjoy your favourite subscribed channel as you do with
a FTA card.

14
Documentation/fb/cyblafb/bugs Normal file
View file

@ -0,0 +1,14 @@
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 Normal file
View file

@ -0,0 +1,7 @@
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 Normal file
View file

@ -0,0 +1,17 @@
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.

155
Documentation/fb/cyblafb/fb.modes Normal file
View file

@ -0,0 +1,155 @@
#
# 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 640 480 640 3756 8
timings 47619 4294967256 24 17 0 216 3
endmode
mode "640x480-60"
geometry 640 480 640 3756 8
timings 39682 4294967256 24 17 0 216 3
endmode
mode "640x480-70"
geometry 640 480 640 3756 8
timings 34013 4294967256 24 17 0 216 3
endmode
mode "640x480-72"
geometry 640 480 640 3756 8
timings 33068 4294967256 24 17 0 216 3
endmode
mode "640x480-75"
geometry 640 480 640 3756 8
timings 31746 4294967256 24 17 0 216 3
endmode
mode "640x480-80"
geometry 640 480 640 3756 8
timings 29761 4294967256 24 17 0 216 3
endmode
mode "640x480-85"
geometry 640 480 640 3756 8
timings 28011 4294967256 24 17 0 216 3
endmode
mode "800x600-50"
geometry 800 600 800 3221 8
timings 30303 96 24 14 0 136 11
endmode
mode "800x600-60"
geometry 800 600 800 3221 8
timings 25252 96 24 14 0 136 11
endmode
mode "800x600-70"
geometry 800 600 800 3221 8
timings 21645 96 24 14 0 136 11
endmode
mode "800x600-72"
geometry 800 600 800 3221 8
timings 21043 96 24 14 0 136 11
endmode
mode "800x600-75"
geometry 800 600 800 3221 8
timings 20202 96 24 14 0 136 11
endmode
mode "800x600-80"
geometry 800 600 800 3221 8
timings 18939 96 24 14 0 136 11
endmode
mode "800x600-85"
geometry 800 600 800 3221 8
timings 17825 96 24 14 0 136 11
endmode
mode "1024x768-50"
geometry 1024 768 1024 2815 8
timings 19054 144 24 29 0 120 3
endmode
mode "1024x768-60"
geometry 1024 768 1024 2815 8
timings 15880 144 24 29 0 120 3
endmode
mode "1024x768-70"
geometry 1024 768 1024 2815 8
timings 13610 144 24 29 0 120 3
endmode
mode "1024x768-72"
geometry 1024 768 1024 2815 8
timings 13232 144 24 29 0 120 3
endmode
mode "1024x768-75"
geometry 1024 768 1024 2815 8
timings 12703 144 24 29 0 120 3
endmode
mode "1024x768-80"
geometry 1024 768 1024 2815 8
timings 11910 144 24 29 0 120 3
endmode
mode "1024x768-85"
geometry 1024 768 1024 2815 8
timings 11209 144 24 29 0 120 3
endmode
mode "1280x1024-50"
geometry 1280 1024 1280 2662 8
timings 11114 232 16 39 0 160 3
endmode
mode "1280x1024-60"
geometry 1280 1024 1280 2662 8
timings 9262 232 16 39 0 160 3
endmode
mode "1280x1024-70"
geometry 1280 1024 1280 2662 8
timings 7939 232 16 39 0 160 3
endmode
mode "1280x1024-72"
geometry 1280 1024 1280 2662 8
timings 7719 232 16 39 0 160 3
endmode
mode "1280x1024-75"
geometry 1280 1024 1280 2662 8
timings 7410 232 16 39 0 160 3
endmode
mode "1280x1024-80"
geometry 1280 1024 1280 2662 8
timings 6946 232 16 39 0 160 3
endmode
mode "1280x1024-85"
geometry 1280 1024 1280 2662 8
timings 6538 232 16 39 0 160 3
endmode

80
Documentation/fb/cyblafb/performance Normal file
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@ -0,0 +1,80 @@
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 | | | |
| | | | |
| | | | |
| | | | |
+-----------+-----------------+-----------------+-----------------+

32
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@ -0,0 +1,32 @@
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.
xpanning Who needs it?
ioctls Who needs it?
TV-out Will be done later
??? Feel free to contact me if you have any
feature requests

206
Documentation/fb/cyblafb/usage Normal file
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@ -0,0 +1,206 @@
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.
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 xres to differ from xres_virtual
- 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.
Any request that violates the rules given above will be ignored and
fbset will return an error.
If you program a virtual y resolution higher than the hardware limit,
cyblafb will silently decrease that value to the highest possible
value.
Attempts to disable acceleration are ignored.
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!
vesafb allows cyblafb to be loaded after vesafb has been
loaded. See sections "Module unloading ...".
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 vesafb=1
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

85
Documentation/fb/cyblafb/whycyblafb Normal file
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@ -0,0 +1,85 @@
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

56
Documentation/fb/intel810.txt
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@ -5,6 +5,7 @@ Intel 810/815 Framebuffer driver
March 17, 2002
First Released: July 2001
Last Update: September 12, 2005
================================================================
A. Introduction
@ -44,6 +45,8 @@ B. Features
- Hardware Cursor Support
- Supports EDID probing either by DDC/I2C or through the BIOS
C. List of available options
a. "video=i810fb"
@ -52,14 +55,17 @@ C. List of available options
Recommendation: required
b. "xres:<value>"
select horizontal resolution in pixels
select horizontal resolution in pixels. (This parameter will be
ignored if 'mode_option' is specified. See 'o' below).
Recommendation: user preference
(default = 640)
c. "yres:<value>"
select vertical resolution in scanlines. If Discrete Video Timings
is enabled, this will be ignored and computed as 3*xres/4.
is enabled, this will be ignored and computed as 3*xres/4. (This
parameter will be ignored if 'mode_option' is specified. See 'o'
below)
Recommendation: user preference
(default = 480)
@ -86,7 +92,8 @@ C. List of available options
g. "hsync1/hsync2:<value>"
select the minimum and maximum Horizontal Sync Frequency of the
monitor in KHz. If a using a fixed frequency monitor, hsync1 must
be equal to hsync2.
be equal to hsync2. If EDID probing is successful, these will be
ignored and values will be taken from the EDID block.
Recommendation: check monitor manual for correct values
default (29/30)
@ -94,7 +101,8 @@ C. List of available options
h. "vsync1/vsync2:<value>"
select the minimum and maximum Vertical Sync Frequency of the monitor
in Hz. You can also use this option to lock your monitor's refresh
rate.
rate. If EDID probing is successful, these will be ignored and values
will be taken from the EDID block.
Recommendation: check monitor manual for correct values
(default = 60/60)
@ -154,7 +162,11 @@ C. List of available options
Recommendation: do not set
(default = not set)
o. <xres>x<yres>[-<bpp>][@<refresh>]
The driver will now accept specification of boot mode option. If this
is specified, the options 'xres' and 'yres' will be ignored. See
Documentation/fb/modedb.txt for usage.
D. Kernel booting
Separate each option/option-pair by commas (,) and the option from its value
@ -176,7 +188,10 @@ will be computed based on the hsync1/hsync2 and vsync1/vsync2 values.
IMPORTANT:
You must include hsync1, hsync2, vsync1 and vsync2 to enable video modes
better than 640x480 at 60Hz.
better than 640x480 at 60Hz. HOWEVER, if your chipset/display combination
supports I2C and has an EDID block, you can safely exclude hsync1, hsync2,
vsync1 and vsync2 parameters. These parameters will be taken from the EDID
block.
E. Module options
@ -217,32 +232,21 @@ F. Setup
This is required. The option is under "Character Devices"
d. Under "Graphics Support", select "Intel 810/815" either statically
or as a module. Choose "use VESA GTF for video timings" if you
need to maximize the capability of your display. To be on the
or as a module. Choose "use VESA Generalized Timing Formula" if
you need to maximize the capability of your display. To be on the
safe side, you can leave this unselected.
e. If you want a framebuffer console, enable it under "Console
e. If you want support for DDC/I2C probing (Plug and Play Displays),
set 'Enable DDC Support' to 'y'. To make this option appear, set
'use VESA Generalized Timing Formula' to 'y'.
f. If you want a framebuffer console, enable it under "Console
Drivers"
f. Compile your kernel.
g. Compile your kernel.
g. Load the driver as described in section D and E.
h. Load the driver as described in section D and E.
Optional:
h. If you are going to run XFree86 with its native drivers, the
standard XFree86 4.1.0 and 4.2.0 drivers should work as is.
However, there's a bug in the XFree86 i810 drivers. It attempts
to use XAA even when switched to the console. This will crash
your server. I have a fix at this site:
http://i810fb.sourceforge.net.
You can either use the patch, or just replace
/usr/X11R6/lib/modules/drivers/i810_drv.o
with the one provided at the website.
i. Try the DirectFB (http://www.directfb.org) + the i810 gfxdriver
patch to see the chipset in action (or inaction :-).

73
Documentation/fb/modedb.txt
View file

@ -20,12 +20,83 @@ in a video= option, fbmem considers that to be a global video mode option.
Valid mode specifiers (mode_option argument):
<xres>x<yres>[-<bpp>][@<refresh>]
<xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m]
<name>[-<bpp>][@<refresh>]
with <xres>, <yres>, <bpp> and <refresh> decimal numbers and <name> a string.
Things between square brackets are optional.
If 'M' is specified in the mode_option argument (after <yres> and before
<bpp> and <refresh>, if specified) the timings will be calculated using
VESA(TM) Coordinated Video Timings instead of looking up the mode from a table.
If 'R' is specified, do a 'reduced blanking' calculation for digital displays.
If 'i' is specified, calculate for an interlaced mode. And if 'm' is
specified, add margins to the calculation (1.8% of xres rounded down to 8
pixels and 1.8% of yres).
Sample usage: 1024x768M@60m - CVT timing with margins
***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo *****
What is the VESA(TM) Coordinated Video Timings (CVT)?
From the VESA(TM) Website:
"The purpose of CVT is to provide a method for generating a consistent
and coordinated set of standard formats, display refresh rates, and
timing specifications for computer display products, both those
employing CRTs, and those using other display technologies. The
intention of CVT is to give both source and display manufacturers a
common set of tools to enable new timings to be developed in a
consistent manner that ensures greater compatibility."
This is the third standard approved by VESA(TM) concerning video timings. The
first was the Discrete Video Timings (DVT) which is a collection of
pre-defined modes approved by VESA(TM). The second is the Generalized Timing
Formula (GTF) which is an algorithm to calculate the timings, given the
pixelclock, the horizontal sync frequency, or the vertical refresh rate.
The GTF is limited by the fact that it is designed mainly for CRT displays.
It artificially increases the pixelclock because of its high blanking
requirement. This is inappropriate for digital display interface with its high
data rate which requires that it conserves the pixelclock as much as possible.
Also, GTF does not take into account the aspect ratio of the display.
The CVT addresses these limitations. If used with CRT's, the formula used
is a derivation of GTF with a few modifications. If used with digital
displays, the "reduced blanking" calculation can be used.
From the framebuffer subsystem perspective, new formats need not be added
to the global mode database whenever a new mode is released by display
manufacturers. Specifying for CVT will work for most, if not all, relatively
new CRT displays and probably with most flatpanels, if 'reduced blanking'
calculation is specified. (The CVT compatibility of the display can be
determined from its EDID. The version 1.3 of the EDID has extra 128-byte
blocks where additional timing information is placed. As of this time, there
is no support yet in the layer to parse this additional blocks.)
CVT also introduced a new naming convention (should be seen from dmesg output):
<pix>M<a>[-R]
where: pix = total amount of pixels in MB (xres x yres)
M = always present
a = aspect ratio (3 - 4:3; 4 - 5:4; 9 - 15:9, 16:9; A - 16:10)
-R = reduced blanking
example: .48M3-R - 800x600 with reduced blanking
Note: VESA(TM) has restrictions on what is a standard CVT timing:
- aspect ratio can only be one of the above values
- acceptable refresh rates are 50, 60, 70 or 85 Hz only
- if reduced blanking, the refresh rate must be at 60Hz
If one of the above are not satisfied, the kernel will print a warning but the
timings will still be calculated.
***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo *****
To find a suitable video mode, you just call
int __init fb_find_mode(struct fb_var_screeninfo *var,

8
Documentation/feature-removal-schedule.txt
View file

@ -17,14 +17,6 @@ Who: Greg Kroah-Hartman <greg@kroah.com>
---------------------------
What: ACPI S4bios support
When: May 2005
Why: Noone uses it, and it probably does not work, anyway. swsusp is
faster, more reliable, and people are actually using it.
Who: Pavel Machek <pavel@suse.cz>
---------------------------
What: io_remap_page_range() (macro or function)
When: September 2005
Why: Replaced by io_remap_pfn_range() which allows more memory space

123
Documentation/filesystems/files.txt Normal file
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@ -0,0 +1,123 @@
File management in the Linux kernel
-----------------------------------
This document describes how locking for files (struct file)
and file descriptor table (struct files) works.
Up until 2.6.12, the file descriptor table has been protected
with a lock (files->file_lock) and reference count (files->count).
->file_lock protected accesses to all the file related fields
of the table. ->count was used for sharing the file descriptor
table between tasks cloned with CLONE_FILES flag. Typically
this would be the case for posix threads. As with the common
refcounting model in the kernel, the last task doing
a put_files_struct() frees the file descriptor (fd) table.
The files (struct file) themselves are protected using
reference count (->f_count).
In the new lock-free model of file descriptor management,
the reference counting is similar, but the locking is
based on RCU. The file descriptor table contains multiple
elements - the fd sets (open_fds and close_on_exec, the
array of file pointers, the sizes of the sets and the array
etc.). In order for the updates to appear atomic to
a lock-free reader, all the elements of the file descriptor
table are in a separate structure - struct fdtable.
files_struct contains a pointer to struct fdtable through
which the actual fd table is accessed. Initially the
fdtable is embedded in files_struct itself. On a subsequent
expansion of fdtable, a new fdtable structure is allocated
and files->fdtab points to the new structure. The fdtable
structure is freed with RCU and lock-free readers either
see the old fdtable or the new fdtable making the update
appear atomic. Here are the locking rules for
the fdtable structure -
1. All references to the fdtable must be done through
the files_fdtable() macro :
struct fdtable *fdt;
rcu_read_lock();
fdt = files_fdtable(files);
....
if (n <= fdt->max_fds)
....
...
rcu_read_unlock();
files_fdtable() uses rcu_dereference() macro which takes care of
the memory barrier requirements for lock-free dereference.
The fdtable pointer must be read within the read-side
critical section.
2. Reading of the fdtable as described above must be protected
by rcu_read_lock()/rcu_read_unlock().
3. For any update to the the fd table, files->file_lock must
be held.
4. To look up the file structure given an fd, a reader
must use either fcheck() or fcheck_files() APIs. These
take care of barrier requirements due to lock-free lookup.
An example :
struct file *file;
rcu_read_lock();
file = fcheck(fd);
if (file) {
...
}
....
rcu_read_unlock();
5. Handling of the file structures is special. Since the look-up
of the fd (fget()/fget_light()) are lock-free, it is possible
that look-up may race with the last put() operation on the
file structure. This is avoided using the rcuref APIs
on ->f_count :
rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
if (rcuref_inc_lf(&file->f_count))
*fput_needed = 1;
else
/* Didn't get the reference, someone's freed */
file = NULL;
}
rcu_read_unlock();
....
return file;
rcuref_inc_lf() detects if refcounts is already zero or
goes to zero during increment. If it does, we fail
fget()/fget_light().
6. Since both fdtable and file structures can be looked up
lock-free, they must be installed using rcu_assign_pointer()
API. If they are looked up lock-free, rcu_dereference()
must be used. However it is advisable to use files_fdtable()
and fcheck()/fcheck_files() which take care of these issues.
7. While updating, the fdtable pointer must be looked up while
holding files->file_lock. If ->file_lock is dropped, then
another thread expand the files thereby creating a new
fdtable and making the earlier fdtable pointer stale.
For example :
spin_lock(&files->file_lock);
fd = locate_fd(files, file, start);
if (fd >= 0) {
/* locate_fd() may have expanded fdtable, load the ptr */
fdt = files_fdtable(files);
FD_SET(fd, fdt->open_fds);
FD_CLR(fd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
.....
Since locate_fd() can drop ->file_lock (and reacquire ->file_lock),
the fdtable pointer (fdt) must be loaded after locate_fd().

315
Documentation/filesystems/fuse.txt Normal file
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@ -0,0 +1,315 @@
Definitions
~~~~~~~~~~~
Userspace filesystem:
A filesystem in which data and metadata are provided by an ordinary
userspace process. The filesystem can be accessed normally through
the kernel interface.
Filesystem daemon:
The process(es) providing the data and metadata of the filesystem.
Non-privileged mount (or user mount):
A userspace filesystem mounted by a non-privileged (non-root) user.
The filesystem daemon is running with the privileges of the mounting
user. NOTE: this is not the same as mounts allowed with the "user"
option in /etc/fstab, which is not discussed here.
Mount owner:
The user who does the mounting.
User:
The user who is performing filesystem operations.
What is FUSE?
~~~~~~~~~~~~~
FUSE is a userspace filesystem framework. It consists of a kernel
module (fuse.ko), a userspace library (libfuse.*) and a mount utility
(fusermount).
One of the most important features of FUSE is allowing secure,
non-privileged mounts. This opens up new possibilities for the use of
filesystems. A good example is sshfs: a secure network filesystem
using the sftp protocol.
The userspace library and utilities are available from the FUSE
homepage:
http://fuse.sourceforge.net/
Mount options
~~~~~~~~~~~~~
'fd=N'
The file descriptor to use for communication between the userspace
filesystem and the kernel. The file descriptor must have been
obtained by opening the FUSE device ('/dev/fuse').
'rootmode=M'
The file mode of the filesystem's root in octal representation.
'user_id=N'
The numeric user id of the mount owner.
'group_id=N'
The numeric group id of the mount owner.
'default_permissions'
By default FUSE doesn't check file access permissions, the
filesystem is free to implement it's access policy or leave it to
the underlying file access mechanism (e.g. in case of network
filesystems). This option enables permission checking, restricting
access based on file mode. This is option is usually useful
together with the 'allow_other' mount option.
'allow_other'
This option overrides the security measure restricting file access
to the user mounting the filesystem. This option is by default only
allowed to root, but this restriction can be removed with a
(userspace) configuration option.
'max_read=N'
With this option the maximum size of read operations can be set.
The default is infinite. Note that the size of read requests is
limited anyway to 32 pages (which is 128kbyte on i386).
How do non-privileged mounts work?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Since the mount() system call is a privileged operation, a helper
program (fusermount) is needed, which is installed setuid root.
The implication of providing non-privileged mounts is that the mount
owner must not be able to use this capability to compromise the
system. Obvious requirements arising from this are:
A) mount owner should not be able to get elevated privileges with the
help of the mounted filesystem
B) mount owner should not get illegitimate access to information from
other users' and the super user's processes
C) mount owner should not be able to induce undesired behavior in
other users' or the super user's processes
How are requirements fulfilled?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A) The mount owner could gain elevated privileges by either:
1) creating a filesystem containing a device file, then opening
this device
2) creating a filesystem containing a suid or sgid application,
then executing this application
The solution is not to allow opening device files and ignore
setuid and setgid bits when executing programs. To ensure this
fusermount always adds "nosuid" and "nodev" to the mount options
for non-privileged mounts.
B) If another user is accessing files or directories in the
filesystem, the filesystem daemon serving requests can record the
exact sequence and timing of operations performed. This
information is otherwise inaccessible to the mount owner, so this
counts as an information leak.
The solution to this problem will be presented in point 2) of C).
C) There are several ways in which the mount owner can induce
undesired behavior in other users' processes, such as:
1) mounting a filesystem over a file or directory which the mount
owner could otherwise not be able to modify (or could only
make limited modifications).
This is solved in fusermount, by checking the access
permissions on the mountpoint and only allowing the mount if
the mount owner can do unlimited modification (has write
access to the mountpoint, and mountpoint is not a "sticky"
directory)
2) Even if 1) is solved the mount owner can change the behavior
of other users' processes.
i) It can slow down or indefinitely delay the execution of a
filesystem operation creating a DoS against the user or the
whole system. For example a suid application locking a
system file, and then accessing a file on the mount owner's
filesystem could be stopped, and thus causing the system
file to be locked forever.
ii) It can present files or directories of unlimited length, or
directory structures of unlimited depth, possibly causing a
system process to eat up diskspace, memory or other
resources, again causing DoS.
The solution to this as well as B) is not to allow processes
to access the filesystem, which could otherwise not be
monitored or manipulated by the mount owner. Since if the
mount owner can ptrace a process, it can do all of the above
without using a FUSE mount, the same criteria as used in
ptrace can be used to check if a process is allowed to access
the filesystem or not.
Note that the ptrace check is not strictly necessary to
prevent B/2/i, it is enough to check if mount owner has enough
privilege to send signal to the process accessing the
filesystem, since SIGSTOP can be used to get a similar effect.
I think these limitations are unacceptable?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If a sysadmin trusts the users enough, or can ensure through other
measures, that system processes will never enter non-privileged
mounts, it can relax the last limitation with a "user_allow_other"
config option. If this config option is set, the mounting user can
add the "allow_other" mount option which disables the check for other
users' processes.
Kernel - userspace interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following diagram shows how a filesystem operation (in this
example unlink) is performed in FUSE.
NOTE: everything in this description is greatly simplified
| "rm /mnt/fuse/file" | FUSE filesystem daemon
| |
| | >sys_read()
| | >fuse_dev_read()
| | >request_wait()
| | [sleep on fc->waitq]
| |
| >sys_unlink() |
| >fuse_unlink() |
| [get request from |
| fc->unused_list] |
| >request_send() |
| [queue req on fc->pending] |
| [wake up fc->waitq] | [woken up]
| >request_wait_answer() |
| [sleep on req->waitq] |
| | <request_wait()
| | [remove req from fc->pending]
| | [copy req to read buffer]
| | [add req to fc->processing]
| | <fuse_dev_read()
| | <sys_read()
| |
| | [perform unlink]
| |
| | >sys_write()
| | >fuse_dev_write()
| | [look up req in fc->processing]
| | [remove from fc->processing]
| | [copy write buffer to req]
| [woken up] | [wake up req->waitq]
| | <fuse_dev_write()
| | <sys_write()
| <request_wait_answer() |
| <request_send() |
| [add request to |
| fc->unused_list] |
| <fuse_unlink() |
| <sys_unlink() |
There are a couple of ways in which to deadlock a FUSE filesystem.
Since we are talking about unprivileged userspace programs,
something must be done about these.
Scenario 1 - Simple deadlock
-----------------------------
| "rm /mnt/fuse/file" | FUSE filesystem daemon
| |
| >sys_unlink("/mnt/fuse/file") |
| [acquire inode semaphore |
| for "file"] |
| >fuse_unlink() |
| [sleep on req->waitq] |
| | <sys_read()
| | >sys_unlink("/mnt/fuse/file")
| | [acquire inode semaphore
| | for "file"]
| | *DEADLOCK*
The solution for this is to allow requests to be interrupted while
they are in userspace:
| [interrupted by signal] |
| <fuse_unlink() |
| [release semaphore] | [semaphore acquired]
| <sys_unlink() |
| | >fuse_unlink()
| | [queue req on fc->pending]
| | [wake up fc->waitq]
| | [sleep on req->waitq]
If the filesystem daemon was single threaded, this will stop here,
since there's no other thread to dequeue and execute the request.
In this case the solution is to kill the FUSE daemon as well. If
there are multiple serving threads, you just have to kill them as
long as any remain.
Moral: a filesystem which deadlocks, can soon find itself dead.
Scenario 2 - Tricky deadlock
----------------------------
This one needs a carefully crafted filesystem. It's a variation on
the above, only the call back to the filesystem is not explicit,
but is caused by a pagefault.
| Kamikaze filesystem thread 1 | Kamikaze filesystem thread 2
| |
| [fd = open("/mnt/fuse/file")] | [request served normally]
| [mmap fd to 'addr'] |
| [close fd] | [FLUSH triggers 'magic' flag]
| [read a byte from addr] |
| >do_page_fault() |
| [find or create page] |
| [lock page] |
| >fuse_readpage() |
| [queue READ request] |
| [sleep on req->waitq] |
| | [read request to buffer]
| | [create reply header before addr]
| | >sys_write(addr - headerlength)
| | >fuse_dev_write()
| | [look up req in fc->processing]
| | [remove from fc->processing]
| | [copy write buffer to req]
| | >do_page_fault()
| | [find or create page]
| | [lock page]
| | * DEADLOCK *
Solution is again to let the the request be interrupted (not
elaborated further).
An additional problem is that while the write buffer is being
copied to the request, the request must not be interrupted. This
is because the destination address of the copy may not be valid
after the request is interrupted.
This is solved with doing the copy atomically, and allowing
interruption while the page(s) belonging to the write buffer are
faulted with get_user_pages(). The 'req->locked' flag indicates
when the copy is taking place, and interruption is delayed until
this flag is unset.

40
Documentation/filesystems/proc.txt
View file

@ -1241,16 +1241,38 @@ swap-intensive.
overcommit_memory
-----------------
This file contains one value. The following algorithm is used to decide if
there's enough memory: if the value of overcommit_memory is positive, then
there's always enough memory. This is a useful feature, since programs often
malloc() huge amounts of memory 'just in case', while they only use a small
part of it. Leaving this value at 0 will lead to the failure of such a huge
malloc(), when in fact the system has enough memory for the program to run.
Controls overcommit of system memory, possibly allowing processes
to allocate (but not use) more memory than is actually available.
On the other hand, enabling this feature can cause you to run out of memory
and thrash the system to death, so large and/or important servers will want to
set this value to 0.
0 - Heuristic overcommit handling. Obvious overcommits of
address space are refused. Used for a typical system. It
ensures a seriously wild allocation fails while allowing
overcommit to reduce swap usage. root is allowed to
allocate slighly more memory in this mode. This is the
default.
1 - Always overcommit. Appropriate for some scientific
applications.
2 - Don't overcommit. The total address space commit
for the system is not permitted to exceed swap plus a
configurable percentage (default is 50) of physical RAM.
Depending on the percentage you use, in most situations
this means a process will not be killed while attempting
to use already-allocated memory but will receive errors
on memory allocation as appropriate.
overcommit_ratio
----------------
Percentage of physical memory size to include in overcommit calculations
(see above.)
Memory allocation limit = swapspace + physmem * (overcommit_ratio / 100)
swapspace = total size of all swap areas
physmem = size of physical memory in system
nr_hugepages and hugetlb_shm_group
----------------------------------

95
Documentation/filesystems/v9fs.txt Normal file
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@ -0,0 +1,95 @@
V9FS: 9P2000 for Linux
======================
ABOUT
=====
v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
This software was originally developed by Ron Minnich <rminnich@lanl.gov>
and Maya Gokhale <maya@lanl.gov>. Additional development by Greg Watson
<gwatson@lanl.gov> and most recently Eric Van Hensbergen
<ericvh@gmail.com> and Latchesar Ionkov <lucho@ionkov.net>.
USAGE
=====
For remote file server:
mount -t 9P 10.10.1.2 /mnt/9
For Plan 9 From User Space applications (http://swtch.com/plan9)
mount -t 9P `namespace`/acme /mnt/9 -o proto=unix,name=$USER
OPTIONS
=======
proto=name select an alternative transport. Valid options are
currently:
unix - specifying a named pipe mount point
tcp - specifying a normal TCP/IP connection
fd - used passed file descriptors for connection
(see rfdno and wfdno)
name=name user name to attempt mount as on the remote server. The
server may override or ignore this value. Certain user
names may require authentication.
aname=name aname specifies the file tree to access when the server is
offering several exported file systems.
debug=n specifies debug level. The debug level is a bitmask.
0x01 = display verbose error messages
0x02 = developer debug (DEBUG_CURRENT)
0x04 = display 9P trace
0x08 = display VFS trace
0x10 = display Marshalling debug
0x20 = display RPC debug
0x40 = display transport debug
0x80 = display allocation debug
rfdno=n the file descriptor for reading with proto=fd
wfdno=n the file descriptor for writing with proto=fd
maxdata=n the number of bytes to use for 9P packet payload (msize)
port=n port to connect to on the remote server
timeout=n request timeouts (in ms) (default 60000ms)
noextend force legacy mode (no 9P2000.u semantics)
uid attempt to mount as a particular uid
gid attempt to mount with a particular gid
afid security channel - used by Plan 9 authentication protocols
nodevmap do not map special files - represent them as normal files.
This can be used to share devices/named pipes/sockets between
hosts. This functionality will be expanded in later versions.
RESOURCES
=========
The Linux version of the 9P server, along with some client-side utilities
can be found at http://v9fs.sf.net (along with a CVS repository of the
development branch of this module). There are user and developer mailing
lists here, as well as a bug-tracker.
For more information on the Plan 9 Operating System check out
http://plan9.bell-labs.com/plan9
For information on Plan 9 from User Space (Plan 9 applications and libraries
ported to Linux/BSD/OSX/etc) check out http://swtch.com/plan9
STATUS
======
The 2.6 kernel support is working on PPC and x86.
PLEASE USE THE SOURCEFORGE BUG-TRACKER TO REPORT PROBLEMS.

439
Documentation/filesystems/vfs.txt
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@ -1,35 +1,27 @@
/* -*- auto-fill -*- */
Overview of the Virtual File System
Overview of the Linux Virtual File System
Richard Gooch <rgooch@atnf.csiro.au>
Original author: Richard Gooch <rgooch@atnf.csiro.au>
5-JUL-1999
Last updated on August 25, 2005
Copyright (C) 1999 Richard Gooch
Copyright (C) 2005 Pekka Enberg
This file is released under the GPLv2.
Conventions used in this document <section>
=================================
Each section in this document will have the string "<section>" at the
right-hand side of the section title. Each subsection will have
"<subsection>" at the right-hand side. These strings are meant to make
it easier to search through the document.
NOTE that the master copy of this document is available online at:
http://www.atnf.csiro.au/~rgooch/linux/docs/vfs.txt
What is it? <section>
What is it?
===========
The Virtual File System (otherwise known as the Virtual Filesystem
Switch) is the software layer in the kernel that provides the
filesystem interface to userspace programs. It also provides an
abstraction within the kernel which allows different filesystem
implementations to co-exist.
implementations to coexist.
A Quick Look At How It Works <section>
A Quick Look At How It Works
============================
In this section I'll briefly describe how things work, before
@ -38,7 +30,8 @@ when user programs open and manipulate files, and then look from the
other view which is how a filesystem is supported and subsequently
mounted.
Opening a File <subsection>
Opening a File
--------------
The VFS implements the open(2), stat(2), chmod(2) and similar system
@ -77,7 +70,7 @@ back to userspace.
Opening a file requires another operation: allocation of a file
structure (this is the kernel-side implementation of file
descriptors). The freshly allocated file structure is initialised with
descriptors). The freshly allocated file structure is initialized with
a pointer to the dentry and a set of file operation member functions.
These are taken from the inode data. The open() file method is then
called so the specific filesystem implementation can do it's work. You
@ -102,7 +95,8 @@ filesystem or driver code at the same time, on different
processors. You should ensure that access to shared resources is
protected by appropriate locks.
Registering and Mounting a Filesystem <subsection>
Registering and Mounting a Filesystem
-------------------------------------
If you want to support a new kind of filesystem in the kernel, all you
@ -123,17 +117,21 @@ updated to point to the root inode for the new filesystem.
It's now time to look at things in more detail.
struct file_system_type <section>
struct file_system_type
=======================
This describes the filesystem. As of kernel 2.1.99, the following
This describes the filesystem. As of kernel 2.6.13, the following
members are defined:
struct file_system_type {
const char *name;
int fs_flags;
struct super_block *(*read_super) (struct super_block *, void *, int);
struct file_system_type * next;
struct super_block *(*get_sb) (struct file_system_type *, int,
const char *, void *);
void (*kill_sb) (struct super_block *);
struct module *owner;
struct file_system_type * next;
struct list_head fs_supers;
};
name: the name of the filesystem type, such as "ext2", "iso9660",
@ -141,51 +139,97 @@ struct file_system_type {
fs_flags: various flags (i.e. FS_REQUIRES_DEV, FS_NO_DCACHE, etc.)
read_super: the method to call when a new instance of this
get_sb: the method to call when a new instance of this
filesystem should be mounted
next: for internal VFS use: you should initialise this to NULL
kill_sb: the method to call when an instance of this filesystem
should be unmounted
The read_super() method has the following arguments:
owner: for internal VFS use: you should initialize this to THIS_MODULE in
most cases.
next: for internal VFS use: you should initialize this to NULL
The get_sb() method has the following arguments:
struct super_block *sb: the superblock structure. This is partially
initialised by the VFS and the rest must be initialised by the
read_super() method
initialized by the VFS and the rest must be initialized by the
get_sb() method
int flags: mount flags
const char *dev_name: the device name we are mounting.
void *data: arbitrary mount options, usually comes as an ASCII
string
int silent: whether or not to be silent on error
The read_super() method must determine if the block device specified
The get_sb() method must determine if the block device specified
in the superblock contains a filesystem of the type the method
supports. On success the method returns the superblock pointer, on
failure it returns NULL.
The most interesting member of the superblock structure that the
read_super() method fills in is the "s_op" field. This is a pointer to
get_sb() method fills in is the "s_op" field. This is a pointer to
a "struct super_operations" which describes the next level of the
filesystem implementation.
Usually, a filesystem uses generic one of the generic get_sb()
implementations and provides a fill_super() method instead. The
generic methods are:
struct super_operations <section>
get_sb_bdev: mount a filesystem residing on a block device
get_sb_nodev: mount a filesystem that is not backed by a device
get_sb_single: mount a filesystem which shares the instance between
all mounts
A fill_super() method implementation has the following arguments:
struct super_block *sb: the superblock structure. The method fill_super()
must initialize this properly.
void *data: arbitrary mount options, usually comes as an ASCII
string
int silent: whether or not to be silent on error
struct super_operations
=======================
This describes how the VFS can manipulate the superblock of your
filesystem. As of kernel 2.1.99, the following members are defined:
filesystem. As of kernel 2.6.13, the following members are defined:
struct super_operations {
void (*read_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*put_inode) (struct inode *);
void (*drop_inode) (struct inode *);
void (*delete_inode) (struct inode *);
int (*notify_change) (struct dentry *, struct iattr *);
void (*put_super) (struct super_block *);
void (*write_super) (struct super_block *);
int (*statfs) (struct super_block *, struct statfs *, int);
int (*remount_fs) (struct super_block *, int *, char *);
void (*clear_inode) (struct inode *);
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
void (*read_inode) (struct inode *);
void (*dirty_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*put_inode) (struct inode *);
void (*drop_inode) (struct inode *);
void (*delete_inode) (struct inode *);
void (*put_super) (struct super_block *);
void (*write_super) (struct super_block *);
int (*sync_fs)(struct super_block *sb, int wait);
void (*write_super_lockfs) (struct super_block *);
void (*unlockfs) (struct super_block *);
int (*statfs) (struct super_block *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void (*clear_inode) (struct inode *);
void (*umount_begin) (struct super_block *);
void (*sync_inodes) (struct super_block *sb,
struct writeback_control *wbc);
int (*show_options)(struct seq_file *, struct vfsmount *);
ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
};
All methods are called without any locks being held, unless otherwise
@ -193,43 +237,62 @@ noted. This means that most methods can block safely. All methods are
only called from a process context (i.e. not from an interrupt handler
or bottom half).
alloc_inode: this method is called by inode_alloc() to allocate memory
for struct inode and initialize it.
destroy_inode: this method is called by destroy_inode() to release
resources allocated for struct inode.
read_inode: this method is called to read a specific inode from the
mounted filesystem. The "i_ino" member in the "struct inode"
will be initialised by the VFS to indicate which inode to
read. Other members are filled in by this method
mounted filesystem. The i_ino member in the struct inode is
initialized by the VFS to indicate which inode to read. Other
members are filled in by this method.
You can set this to NULL and use iget5_locked() instead of iget()
to read inodes. This is necessary for filesystems for which the
inode number is not sufficient to identify an inode.
dirty_inode: this method is called by the VFS to mark an inode dirty.
write_inode: this method is called when the VFS needs to write an
inode to disc. The second parameter indicates whether the write
should be synchronous or not, not all filesystems check this flag.
put_inode: called when the VFS inode is removed from the inode
cache. This method is optional
cache.
drop_inode: called when the last access to the inode is dropped,
with the inode_lock spinlock held.
This method should be either NULL (normal unix filesystem
This method should be either NULL (normal UNIX filesystem
semantics) or "generic_delete_inode" (for filesystems that do not
want to cache inodes - causing "delete_inode" to always be
called regardless of the value of i_nlink)
The "generic_delete_inode()" behaviour is equivalent to the
The "generic_delete_inode()" behavior is equivalent to the
old practice of using "force_delete" in the put_inode() case,
but does not have the races that the "force_delete()" approach
had.
delete_inode: called when the VFS wants to delete an inode
notify_change: called when VFS inode attributes are changed. If this
is NULL the VFS falls back to the write_inode() method. This
is called with the kernel lock held
put_super: called when the VFS wishes to free the superblock
(i.e. unmount). This is called with the superblock lock held
write_super: called when the VFS superblock needs to be written to
disc. This method is optional
sync_fs: called when VFS is writing out all dirty data associated with
a superblock. The second parameter indicates whether the method
should wait until the write out has been completed. Optional.
write_super_lockfs: called when VFS is locking a filesystem and forcing
it into a consistent state. This function is currently used by the
Logical Volume Manager (LVM).
unlockfs: called when VFS is unlocking a filesystem and making it writable
again.
statfs: called when the VFS needs to get filesystem statistics. This
is called with the kernel lock held
@ -238,21 +301,31 @@ or bottom half).
clear_inode: called then the VFS clears the inode. Optional
umount_begin: called when the VFS is unmounting a filesystem.
sync_inodes: called when the VFS is writing out dirty data associated with
a superblock.
show_options: called by the VFS to show mount options for /proc/<pid>/mounts.
quota_read: called by the VFS to read from filesystem quota file.
quota_write: called by the VFS to write to filesystem quota file.
The read_inode() method is responsible for filling in the "i_op"
field. This is a pointer to a "struct inode_operations" which
describes the methods that can be performed on individual inodes.
struct inode_operations <section>
struct inode_operations
=======================
This describes how the VFS can manipulate an inode in your
filesystem. As of kernel 2.1.99, the following members are defined:
filesystem. As of kernel 2.6.13, the following members are defined:
struct inode_operations {
struct file_operations * default_file_ops;
int (*create) (struct inode *,struct dentry *,int);
int (*lookup) (struct inode *,struct dentry *);
int (*create) (struct inode *,struct dentry *,int, struct nameidata *);
struct dentry * (*lookup) (struct inode *,struct dentry *, struct nameidata *);
int (*link) (struct dentry *,struct inode *,struct dentry *);
int (*unlink) (struct inode *,struct dentry *);
int (*symlink) (struct inode *,struct dentry *,const char *);
@ -261,25 +334,22 @@ struct inode_operations {
int (*mknod) (struct inode *,struct dentry *,int,dev_t);
int (*rename) (struct inode *, struct dentry *,
struct inode *, struct dentry *);
int (*readlink) (struct dentry *, char *,int);
struct dentry * (*follow_link) (struct dentry *, struct dentry *);
int (*readpage) (struct file *, struct page *);
int (*writepage) (struct page *page, struct writeback_control *wbc);
int (*bmap) (struct inode *,int);
int (*readlink) (struct dentry *, char __user *,int);
void * (*follow_link) (struct dentry *, struct nameidata *);
void (*put_link) (struct dentry *, struct nameidata *, void *);
void (*truncate) (struct inode *);
int (*permission) (struct inode *, int);
int (*smap) (struct inode *,int);
int (*updatepage) (struct file *, struct page *, const char *,
unsigned long, unsigned int, int);
int (*revalidate) (struct dentry *);
int (*permission) (struct inode *, int, struct nameidata *);
int (*setattr) (struct dentry *, struct iattr *);
int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t);
ssize_t (*listxattr) (struct dentry *, char *, size_t);
int (*removexattr) (struct dentry *, const char *);
};
Again, all methods are called without any locks being held, unless
otherwise noted.
default_file_ops: this is a pointer to a "struct file_operations"
which describes how to open and then manipulate open files
create: called by the open(2) and creat(2) system calls. Only
required if you want to support regular files. The dentry you
get should not have an inode (i.e. it should be a negative
@ -328,31 +398,143 @@ otherwise noted.
you want to support reading symbolic links
follow_link: called by the VFS to follow a symbolic link to the
inode it points to. Only required if you want to support
symbolic links
inode it points to. Only required if you want to support
symbolic links. This function returns a void pointer cookie
that is passed to put_link().
put_link: called by the VFS to release resources allocated by
follow_link(). The cookie returned by follow_link() is passed to
to this function as the last parameter. It is used by filesystems
such as NFS where page cache is not stable (i.e. page that was
installed when the symbolic link walk started might not be in the
page cache at the end of the walk).
truncate: called by the VFS to change the size of a file. The i_size
field of the inode is set to the desired size by the VFS before
this function is called. This function is called by the truncate(2)
system call and related functionality.
permission: called by the VFS to check for access rights on a POSIX-like
filesystem.
setattr: called by the VFS to set attributes for a file. This function is
called by chmod(2) and related system calls.
getattr: called by the VFS to get attributes of a file. This function is
called by stat(2) and related system calls.
setxattr: called by the VFS to set an extended attribute for a file.
Extended attribute is a name:value pair associated with an inode. This
function is called by setxattr(2) system call.
getxattr: called by the VFS to retrieve the value of an extended attribute
name. This function is called by getxattr(2) function call.
listxattr: called by the VFS to list all extended attributes for a given
file. This function is called by listxattr(2) system call.
removexattr: called by the VFS to remove an extended attribute from a file.
This function is called by removexattr(2) system call.
struct file_operations <section>
struct address_space_operations
===============================
This describes how the VFS can manipulate mapping of a file to page cache in
your filesystem. As of kernel 2.6.13, the following members are defined:
struct address_space_operations {
int (*writepage)(struct page *page, struct writeback_control *wbc);
int (*readpage)(struct file *, struct page *);
int (*sync_page)(struct page *);
int (*writepages)(struct address_space *, struct writeback_control *);
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
sector_t (*bmap)(struct address_space *, sector_t);
int (*invalidatepage) (struct page *, unsigned long);
int (*releasepage) (struct page *, int);
ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
loff_t offset, unsigned long nr_segs);
struct page* (*get_xip_page)(struct address_space *, sector_t,
int);
};
writepage: called by the VM write a dirty page to backing store.
readpage: called by the VM to read a page from backing store.
sync_page: called by the VM to notify the backing store to perform all
queued I/O operations for a page. I/O operations for other pages
associated with this address_space object may also be performed.
writepages: called by the VM to write out pages associated with the
address_space object.
set_page_dirty: called by the VM to set a page dirty.
readpages: called by the VM to read pages associated with the address_space
object.
prepare_write: called by the generic write path in VM to set up a write
request for a page.
commit_write: called by the generic write path in VM to write page to
its backing store.
bmap: called by the VFS to map a logical block offset within object to
physical block number. This method is use by for the legacy FIBMAP
ioctl. Other uses are discouraged.
invalidatepage: called by the VM on truncate to disassociate a page from its
address_space mapping.
releasepage: called by the VFS to release filesystem specific metadata from
a page.
direct_IO: called by the VM for direct I/O writes and reads.
get_xip_page: called by the VM to translate a block number to a page.
The page is valid until the corresponding filesystem is unmounted.
Filesystems that want to use execute-in-place (XIP) need to implement
it. An example implementation can be found in fs/ext2/xip.c.
struct file_operations
======================
This describes how the VFS can manipulate an open file. As of kernel
2.1.99, the following members are defined:
2.6.13, the following members are defined:
struct file_operations {
loff_t (*llseek) (struct file *, loff_t, int);
ssize_t (*read) (struct file *, char *, size_t, loff_t *);
ssize_t (*write) (struct file *, const char *, size_t, loff_t *);
ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
ssize_t (*aio_read) (struct kiocb *, char __user *, size_t, loff_t);
ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
ssize_t (*aio_write) (struct kiocb *, const char __user *, size_t, loff_t);
int (*readdir) (struct file *, void *, filldir_t);
unsigned int (*poll) (struct file *, struct poll_table_struct *);
int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
int (*open) (struct inode *, struct file *);
int (*flush) (struct file *);
int (*release) (struct inode *, struct file *);
int (*fsync) (struct file *, struct dentry *);
int (*fasync) (struct file *, int);
int (*check_media_change) (kdev_t dev);
int (*revalidate) (kdev_t dev);
int (*fsync) (struct file *, struct dentry *, int datasync);
int (*aio_fsync) (struct kiocb *, int datasync);
int (*fasync) (int, struct file *, int);
int (*lock) (struct file *, int, struct file_lock *);
ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
int (*check_flags)(int);
int (*dir_notify)(struct file *filp, unsigned long arg);
int (*flock) (struct file *, int, struct file_lock *);
};
Again, all methods are called without any locks being held, unless
@ -362,8 +544,12 @@ otherwise noted.
read: called by read(2) and related system calls
aio_read: called by io_submit(2) and other asynchronous I/O operations
write: called by write(2) and related system calls
aio_write: called by io_submit(2) and other asynchronous I/O operations
readdir: called when the VFS needs to read the directory contents
poll: called by the VFS when a process wants to check if there is
@ -372,18 +558,25 @@ otherwise noted.
ioctl: called by the ioctl(2) system call
unlocked_ioctl: called by the ioctl(2) system call. Filesystems that do not
require the BKL should use this method instead of the ioctl() above.
compat_ioctl: called by the ioctl(2) system call when 32 bit system calls
are used on 64 bit kernels.
mmap: called by the mmap(2) system call
open: called by the VFS when an inode should be opened. When the VFS
opens a file, it creates a new "struct file" and initialises
the "f_op" file operations member with the "default_file_ops"
field in the inode structure. It then calls the open method
for the newly allocated file structure. You might think that
the open method really belongs in "struct inode_operations",
and you may be right. I think it's done the way it is because
it makes filesystems simpler to implement. The open() method
is a good place to initialise the "private_data" member in the
file structure if you want to point to a device structure
opens a file, it creates a new "struct file". It then calls the
open method for the newly allocated file structure. You might
think that the open method really belongs in
"struct inode_operations", and you may be right. I think it's
done the way it is because it makes filesystems simpler to
implement. The open() method is a good place to initialize the
"private_data" member in the file structure if you want to point
to a device structure
flush: called by the close(2) system call to flush a file
release: called when the last reference to an open file is closed
@ -392,6 +585,23 @@ otherwise noted.
fasync: called by the fcntl(2) system call when asynchronous
(non-blocking) mode is enabled for a file
lock: called by the fcntl(2) system call for F_GETLK, F_SETLK, and F_SETLKW
commands
readv: called by the readv(2) system call
writev: called by the writev(2) system call
sendfile: called by the sendfile(2) system call
get_unmapped_area: called by the mmap(2) system call
check_flags: called by the fcntl(2) system call for F_SETFL command
dir_notify: called by the fcntl(2) system call for F_NOTIFY command
flock: called by the flock(2) system call
Note that the file operations are implemented by the specific
filesystem in which the inode resides. When opening a device node
(character or block special) most filesystems will call special
@ -400,29 +610,28 @@ driver information. These support routines replace the filesystem file
operations with those for the device driver, and then proceed to call
the new open() method for the file. This is how opening a device file
in the filesystem eventually ends up calling the device driver open()
method. Note the devfs (the Device FileSystem) has a more direct path
from device node to device driver (this is an unofficial kernel
patch).
method.
Directory Entry Cache (dcache) <section>
------------------------------
Directory Entry Cache (dcache)
==============================
struct dentry_operations
========================
------------------------
This describes how a filesystem can overload the standard dentry
operations. Dentries and the dcache are the domain of the VFS and the
individual filesystem implementations. Device drivers have no business
here. These methods may be set to NULL, as they are either optional or
the VFS uses a default. As of kernel 2.1.99, the following members are
the VFS uses a default. As of kernel 2.6.13, the following members are
defined:
struct dentry_operations {
int (*d_revalidate)(struct dentry *);
int (*d_revalidate)(struct dentry *, struct nameidata *);
int (*d_hash) (struct dentry *, struct qstr *);
int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
void (*d_delete)(struct dentry *);
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
};
@ -451,6 +660,7 @@ Each dentry has a pointer to its parent dentry, as well as a hash list
of child dentries. Child dentries are basically like files in a
directory.
Directory Entry Cache APIs
--------------------------
@ -471,7 +681,7 @@ manipulate dentries:
"d_delete" method is called
d_drop: this unhashes a dentry from its parents hash list. A
subsequent call to dput() will dellocate the dentry if its
subsequent call to dput() will deallocate the dentry if its
usage count drops to 0
d_delete: delete a dentry. If there are no other open references to
@ -507,16 +717,16 @@ up by walking the tree starting with the first component
of the pathname and using that dentry along with the next
component to look up the next level and so on. Since it
is a frequent operation for workloads like multiuser
environments and webservers, it is important to optimize
environments and web servers, it is important to optimize
this path.
Prior to 2.5.10, dcache_lock was acquired in d_lookup and thus
in every component during path look-up. Since 2.5.10 onwards,
fastwalk algorithm changed this by holding the dcache_lock
fast-walk algorithm changed this by holding the dcache_lock
at the beginning and walking as many cached path component
dentries as possible. This signficantly decreases the number
dentries as possible. This significantly decreases the number
of acquisition of dcache_lock. However it also increases the
lock hold time signficantly and affects performance in large
lock hold time significantly and affects performance in large
SMP machines. Since 2.5.62 kernel, dcache has been using
a new locking model that uses RCU to make dcache look-up
lock-free.
@ -527,7 +737,7 @@ protected the hash chain, d_child, d_alias, d_lru lists as well
as d_inode and several other things like mount look-up. RCU-based
changes affect only the way the hash chain is protected. For everything
else the dcache_lock must be taken for both traversing as well as
updating. The hash chain updations too take the dcache_lock.
updating. The hash chain updates too take the dcache_lock.
The significant change is the way d_lookup traverses the hash chain,
it doesn't acquire the dcache_lock for this and rely on RCU to
ensure that the dentry has not been *freed*.
@ -535,14 +745,15 @@ ensure that the dentry has not been *freed*.
Dcache locking details
----------------------
For many multi-user workloads, open() and stat() on files are
very frequently occurring operations. Both involve walking
of path names to find the dentry corresponding to the
concerned file. In 2.4 kernel, dcache_lock was held
during look-up of each path component. Contention and
cacheline bouncing of this global lock caused significant
cache-line bouncing of this global lock caused significant
scalability problems. With the introduction of RCU
in linux kernel, this was worked around by making
in Linux kernel, this was worked around by making
the look-up of path components during path walking lock-free.
@ -562,7 +773,7 @@ Some of the important changes are :
2. Insertion of a dentry into the hash table is done using
hlist_add_head_rcu() which take care of ordering the writes -
the writes to the dentry must be visible before the dentry
is inserted. This works in conjuction with hlist_for_each_rcu()
is inserted. This works in conjunction with hlist_for_each_rcu()
while walking the hash chain. The only requirement is that
all initialization to the dentry must be done before hlist_add_head_rcu()
since we don't have dcache_lock protection while traversing
@ -584,7 +795,7 @@ Some of the important changes are :
the same. In some sense, dcache_rcu path walking looks like
the pre-2.5.10 version.
5. All dentry hash chain updations must take the dcache_lock as well as
5. All dentry hash chain updates must take the dcache_lock as well as
the per-dentry lock in that order. dput() does this to ensure
that a dentry that has just been looked up in another CPU
doesn't get deleted before dget() can be done on it.
@ -640,10 +851,10 @@ handled as described below :
Since we redo the d_parent check and compare name while holding
d_lock, lock-free look-up will not race against d_move().
4. There can be a theoritical race when a dentry keeps coming back
4. There can be a theoretical race when a dentry keeps coming back
to original bucket due to double moves. Due to this look-up may
consider that it has never moved and can end up in a infinite loop.
But this is not any worse that theoritical livelocks we already
But this is not any worse that theoretical livelocks we already
have in the kernel.

2
Documentation/ioctl/cdrom.txt
View file

@ -878,7 +878,7 @@ DVD_READ_STRUCT Read structure
error returns:
EINVAL physical.layer_num exceeds number of layers
EIO Recieved invalid response from drive
EIO Received invalid response from drive

14
Documentation/kbuild/makefiles.txt
View file

@ -31,7 +31,7 @@ This document describes the Linux kernel Makefiles.
=== 6 Architecture Makefiles
--- 6.1 Set variables to tweak the build to the architecture
--- 6.2 Add prerequisites to prepare:
--- 6.2 Add prerequisites to archprepare:
--- 6.3 List directories to visit when descending
--- 6.4 Architecture specific boot images
--- 6.5 Building non-kbuild targets
@ -734,18 +734,18 @@ When kbuild executes the following steps are followed (roughly):
for loadable kernel modules.
--- 6.2 Add prerequisites to prepare:
--- 6.2 Add prerequisites to archprepare:
The prepare: rule is used to list prerequisites that needs to be
The archprepare: rule is used to list prerequisites that needs to be
built before starting to descend down in the subdirectories.
This is usual header files containing assembler constants.
Example:
#arch/s390/Makefile
prepare: include/asm-$(ARCH)/offsets.h
#arch/arm/Makefile
archprepare: maketools
In this example the file include/asm-$(ARCH)/offsets.h will
be built before descending down in the subdirectories.
In this example the file target maketools will be processed
before descending down in the subdirectories.
See also chapter XXX-TODO that describe how kbuild supports
generating offset header files.

16
Documentation/kdump/kdump.txt
View file

@ -39,8 +39,7 @@ SETUP
and apply http://lse.sourceforge.net/kdump/patches/kexec-tools-1.101-kdump.patch
and after that build the source.
2) Download and build the appropriate (latest) kexec/kdump (-mm) kernel
patchset and apply it to the vanilla kernel tree.
2) Download and build the appropriate (2.6.13-rc1 onwards) vanilla kernel.
Two kernels need to be built in order to get this feature working.
@ -84,15 +83,16 @@ SETUP
4) Load the second kernel to be booted using:
kexec -p <second-kernel> --crash-dump --args-linux --append="root=<root-dev>
init 1 irqpoll"
kexec -p <second-kernel> --args-linux --elf32-core-headers
--append="root=<root-dev> init 1 irqpoll"
Note: i) <second-kernel> has to be a vmlinux image. bzImage will not work,
as of now.
ii) By default ELF headers are stored in ELF32 format (for i386). This
is sufficient to represent the physical memory up to 4GB. To store
headers in ELF64 format, specifiy "--elf64-core-headers" on the
kexec command line additionally.
ii) By default ELF headers are stored in ELF64 format. Option
--elf32-core-headers forces generation of ELF32 headers. gdb can
not open ELF64 headers on 32 bit systems. So creating ELF32
headers can come handy for users who have got non-PAE systems and
hence have memory less than 4GB.
iii) Specify "irqpoll" as command line parameter. This reduces driver
initialization failures in second kernel due to shared interrupts.

10
Documentation/kernel-parameters.txt
View file

@ -164,6 +164,15 @@ running once the system is up.
over-ride platform specific driver.
See also Documentation/acpi-hotkey.txt.
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.
ad1816= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
See also Documentation/sound/oss/AD1816.
@ -549,6 +558,7 @@ running once the system is up.
keyboard and can not control its state
(Don't attempt to blink the leds)
i8042.noaux [HW] Don't check for auxiliary (== mouse) port
i8042.nokbd [HW] Don't check/create keyboard port
i8042.nomux [HW] Don't check presence of an active multiplexing
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX

2
Documentation/mono.txt
View file

@ -30,7 +30,7 @@ other program after you have done the following:
Read the file 'binfmt_misc.txt' in this directory to know
more about the configuration process.
3) Add the following enries to /etc/rc.local or similar script
3) Add the following entries to /etc/rc.local or similar script
to be run at system startup:
# Insert BINFMT_MISC module into the kernel

4
Documentation/networking/bonding.txt
View file

@ -1241,7 +1241,7 @@ traffic while still maintaining carrier on.
If running SNMP agents, the bonding driver should be loaded
before any network drivers participating in a bond. This requirement
is due to the the interface index (ipAdEntIfIndex) being associated to
is due to the interface index (ipAdEntIfIndex) being associated to
the first interface found with a given IP address. That is, there is
only one ipAdEntIfIndex for each IP address. For example, if eth0 and
eth1 are slaves of bond0 and the driver for eth0 is loaded before the
@ -1937,7 +1937,7 @@ switches currently available support 802.3ad.
If not explicitly configured (with ifconfig or ip link), the
MAC address of the bonding device is taken from its first slave
device. This MAC address is then passed to all following slaves and
remains persistent (even if the the first slave is removed) until the
remains persistent (even if the first slave is removed) until the
bonding device is brought down or reconfigured.
If you wish to change the MAC address, you can set it with

4
Documentation/networking/wan-router.txt
View file

@ -355,7 +355,7 @@ REVISION HISTORY
There is no functional difference between the two packages
2.0.7 Aug 26, 1999 o Merged X25API code into WANPIPE.
o Fixed a memeory leak for X25API
o Fixed a memory leak for X25API
o Updated the X25API code for 2.2.X kernels.
o Improved NEM handling.
@ -514,7 +514,7 @@ beta2-2.2.0 Jan 8 2001
o Patches for 2.4.0 kernel
o Patches for 2.2.18 kernel
o Minor updates to PPP and CHLDC drivers.
Note: No functinal difference.
Note: No functional difference.
beta3-2.2.9 Jan 10 2001
o I missed the 2.2.18 kernel patches in beta2-2.2.0

2
Documentation/pci.txt
View file

@ -84,7 +84,7 @@ Each entry consists of:
Most drivers don't need to use the driver_data field. Best practice
for use of driver_data is to use it as an index into a static list of
equivalant device types, not to use it as a pointer.
equivalent device types, not to use it as a pointer.
Have a table entry {PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID}
to have probe() called for every PCI device known to the system.

2
Documentation/powerpc/eeh-pci-error-recovery.txt
View file

@ -134,7 +134,7 @@ pci_get_device_by_addr() will find the pci device associated
with that address (if any).
The default include/asm-ppc64/io.h macros readb(), inb(), insb(),
etc. include a check to see if the the i/o read returned all-0xff's.
etc. include a check to see if the i/o read returned all-0xff's.
If so, these make a call to eeh_dn_check_failure(), which in turn
asks the firmware if the all-ff's value is the sign of a true EEH
error. If it is not, processing continues as normal. The grand

2
Documentation/s390/s390dbf.txt
View file

@ -468,7 +468,7 @@ The hex_ascii view shows the data field in hex and ascii representation
The raw view returns a bytestream as the debug areas are stored in memory.
The sprintf view formats the debug entries in the same way as the sprintf
function would do. The sprintf event/expection fuctions write to the
function would do. The sprintf event/expection functions write to the
debug entry a pointer to the format string (size = sizeof(long))
and for each vararg a long value. So e.g. for a debug entry with a format
string plus two varargs one would need to allocate a (3 * sizeof(long))

2
Documentation/scsi/ibmmca.txt
View file

@ -344,7 +344,7 @@
/proc/scsi/ibmmca/<host_no>. ibmmca_proc_info() provides this information.
This table is quite informative for interested users. It shows the load
of commands on the subsystem and wether you are running the bypassed
of commands on the subsystem and whether you are running the bypassed
(software) or integrated (hardware) SCSI-command set (see below). The
amount of accesses is shown. Read, write, modeselect is shown separately
in order to help debugging problems with CD-ROMs or tapedrives.

2
Documentation/sound/alsa/ALSA-Configuration.txt
View file

@ -1459,7 +1459,7 @@ devices where %i is sound card number from zero to seven.
To auto-load an ALSA driver for OSS services, define the string
'sound-slot-%i' where %i means the slot number for OSS, which
corresponds to the card index of ALSA. Usually, define this
as the the same card module.
as the same card module.
An example configuration for a single emu10k1 card is like below:
----- /etc/modprobe.conf

2
Documentation/sparse.txt
View file

@ -57,7 +57,7 @@ With BK, you can just get it from
and DaveJ has tar-balls at
http://www.codemonkey.org.uk/projects/bitkeeper/sparse/
http://www.codemonkey.org.uk/projects/git-snapshots/sparse/
Once you have it, just do

2
Documentation/sysrq.txt
View file

@ -171,7 +171,7 @@ the header 'include/linux/sysrq.h', this will define everything else you need.
Next, you must create a sysrq_key_op struct, and populate it with A) the key
handler function you will use, B) a help_msg string, that will print when SysRQ
prints help, and C) an action_msg string, that will print right before your
handler is called. Your handler must conform to the protoype in 'sysrq.h'.
handler is called. Your handler must conform to the prototype in 'sysrq.h'.
After the sysrq_key_op is created, you can call the macro
register_sysrq_key(int key, struct sysrq_key_op *op_p) that is defined in

2
Documentation/uml/UserModeLinux-HOWTO.txt
View file

@ -2176,7 +2176,7 @@
If you want to access files on the host machine from inside UML, you
can treat it as a separate machine and either nfs mount directories
from the host or copy files into the virtual machine with scp or rcp.
However, since UML is running on the the host, it can access those
However, since UML is running on the host, it can access those
files just like any other process and make them available inside the
virtual machine without needing to use the network.

2
Documentation/usb/gadget_serial.txt
View file

@ -20,7 +20,7 @@ License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA.
This document and the the gadget serial driver itself are
This document and the gadget serial driver itself are
Copyright (C) 2004 by Al Borchers (alborchers@steinerpoint.com).
If you have questions, problems, or suggestions for this driver

4
Documentation/video4linux/CARDLIST.bttv
View file

@ -126,10 +126,12 @@ card=124 - AverMedia AverTV DVB-T 761
card=125 - MATRIX Vision Sigma-SQ
card=126 - MATRIX Vision Sigma-SLC
card=127 - APAC Viewcomp 878(AMAX)
card=128 - DVICO FusionHDTV DVB-T Lite
card=128 - DViCO FusionHDTV DVB-T Lite
card=129 - V-Gear MyVCD
card=130 - Super TV Tuner
card=131 - Tibet Systems 'Progress DVR' CS16
card=132 - Kodicom 4400R (master)
card=133 - Kodicom 4400R (slave)
card=134 - Adlink RTV24
card=135 - DViCO FusionHDTV 5 Lite
card=136 - Acorp Y878F

3
Documentation/video4linux/CARDLIST.saa7134
View file

@ -62,3 +62,6 @@
61 -> Philips TOUGH DVB-T reference design [1131:2004]
62 -> Compro VideoMate TV Gold+II
63 -> Kworld Xpert TV PVR7134
64 -> FlyTV mini Asus Digimatrix [1043:0210,1043:0210]
65 -> V-Stream Studio TV Terminator
66 -> Yuan TUN-900 (saa7135)

1
Documentation/video4linux/CARDLIST.tuner
View file

@ -64,3 +64,4 @@ tuner=62 - Philips TEA5767HN FM Radio
tuner=63 - Philips FMD1216ME MK3 Hybrid Tuner
tuner=64 - LG TDVS-H062F/TUA6034
tuner=65 - Ymec TVF66T5-B/DFF
tuner=66 - LG NTSC (TALN mini series)

2
Documentation/video4linux/Zoran
View file

@ -222,7 +222,7 @@ was introduced in 1991, is used in the DC10 old
can generate: PAL , NTSC , SECAM
The adv717x, should be able to produce PAL N. But you find nothing PAL N
specific in the the registers. Seem that you have to reuse a other standard
specific in the registers. Seem that you have to reuse a other standard
to generate PAL N, maybe it would work if you use the PAL M settings.
==========================

5
Documentation/x86_64/boot-options.txt
View file

@ -11,6 +11,11 @@ Machine check
If your BIOS doesn't do that it's a good idea to enable though
to make sure you log even machine check events that result
in a reboot.
mce=tolerancelevel (number)
0: always panic, 1: panic if deadlock possible,
2: try to avoid panic, 3: never panic or exit (for testing)
default is 1
Can be also set using sysfs which is preferable.
nomce (for compatibility with i386): same as mce=off

49
Kbuild Normal file
View file

@ -0,0 +1,49 @@
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate asm-offsets.h
#####
# 1) Generate asm-offsets.h
#
offsets-file := include/asm-$(ARCH)/asm-offsets.h
always := $(offsets-file)
targets := $(offsets-file)
targets += arch/$(ARCH)/kernel/asm-offsets.s
# Default sed regexp - multiline due to syntax constraints
define sed-y
"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
endef
# Override default regexp for specific architectures
sed-$(CONFIG_MIPS) := "/^@@@/s///p"
quiet_cmd_offsets = GEN $@
define cmd_offsets
mkdir -p $(dir $@); \
cat $< | \
(set -e; \
echo "#ifndef __ASM_OFFSETS_H__"; \
echo "#define __ASM_OFFSETS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by $(srctree)/Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y); \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(ARCH)/kernel/asm-offsets.s: arch/$(ARCH)/kernel/asm-offsets.c FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(offsets-file): arch/$(ARCH)/kernel/asm-offsets.s Kbuild
$(call cmd,offsets)

24
MAINTAINERS
View file

@ -626,6 +626,12 @@ M: rmk@arm.linux.org.uk
W: http://www.arm.linux.org.uk/
S: Maintained
CYBLAFB FRAMEBUFFER DRIVER
P: Knut Petersen
M: Knut_Petersen@t-online.de
L: linux-fbdev-devel@lists.sourceforge.net
S: Maintained
CYCLADES 2X SYNC CARD DRIVER
P: Arnaldo Carvalho de Melo
M: acme@conectiva.com.br
@ -925,6 +931,13 @@ L: linux-tape@vger.kernel.org
W: http://sourceforge.net/projects/ftape
S: Orphan
FUSE: FILESYSTEM IN USERSPACE
P: Miklos Szeredi
M: miklos@szeredi.hu
L: fuse-devel@lists.sourceforge.net
W: http://fuse.sourceforge.net/
S: Maintained
FUTURE DOMAIN TMC-16x0 SCSI DRIVER (16-bit)
P: Rik Faith
M: faith@cs.unc.edu
@ -2691,6 +2704,17 @@ L: rio500-users@lists.sourceforge.net
W: http://rio500.sourceforge.net
S: Maintained
V9FS FILE SYSTEM
P: Eric Van Hensbergen
M: ericvh@gmail.com
P: Ron Minnich
M: rminnich@lanl.gov
P: Latchesar Ionkov
M: lucho@ionkov.net
L: v9fs-developer@lists.sourceforge.net
W: http://v9fs.sf.net
S: Maintained
VIDEO FOR LINUX
P: Mauro Carvalho Chehab
M: mchehab@brturbo.com.br

80
Makefile
View file

@ -334,7 +334,7 @@ KALLSYMS = scripts/kallsyms
PERL = perl
CHECK = sparse
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ $(CF)
MODFLAGS = -DMODULE
CFLAGS_MODULE = $(MODFLAGS)
AFLAGS_MODULE = $(MODFLAGS)
@ -382,6 +382,9 @@ RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn --exclude CV
scripts_basic:
$(Q)$(MAKE) $(build)=scripts/basic
# To avoid any implicit rule to kick in, define an empty command.
scripts/basic/%: scripts_basic ;
.PHONY: outputmakefile
# outputmakefile generate a Makefile to be placed in output directory, if
# using a seperate output directory. This allows convinient use
@ -444,9 +447,8 @@ ifeq ($(config-targets),1)
include $(srctree)/arch/$(ARCH)/Makefile
export KBUILD_DEFCONFIG
config: scripts_basic outputmakefile FORCE
$(Q)$(MAKE) $(build)=scripts/kconfig $@
%config: scripts_basic outputmakefile FORCE
config %config: scripts_basic outputmakefile FORCE
$(Q)mkdir -p include/linux
$(Q)$(MAKE) $(build)=scripts/kconfig $@
else
@ -489,6 +491,7 @@ include .config
# If .config is newer than include/linux/autoconf.h, someone tinkered
# with it and forgot to run make oldconfig
include/linux/autoconf.h: .config
$(Q)mkdir -p include/linux
$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
else
# Dummy target needed, because used as prerequisite
@ -641,8 +644,13 @@ quiet_cmd_vmlinux__ ?= LD $@
# Generate new vmlinux version
quiet_cmd_vmlinux_version = GEN .version
cmd_vmlinux_version = set -e; \
. $(srctree)/scripts/mkversion > .tmp_version; \
mv -f .tmp_version .version; \
if [ ! -r .version ]; then \
rm -f .version; \
echo 1 >.version; \
else \
mv .version .old_version; \
expr 0$$(cat .old_version) + 1 >.version; \
fi; \
$(MAKE) $(build)=init
# Generate System.map
@ -756,6 +764,7 @@ endif # ifdef CONFIG_KALLSYMS
# vmlinux image - including updated kernel symbols
vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) FORCE
$(call if_changed_rule,vmlinux__)
$(Q)rm -f .old_version
# The actual objects are generated when descending,
# make sure no implicit rule kicks in
@ -768,22 +777,27 @@ $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;
# Error messages still appears in the original language
.PHONY: $(vmlinux-dirs)
$(vmlinux-dirs): prepare-all scripts
$(vmlinux-dirs): prepare scripts
$(Q)$(MAKE) $(build)=$@
# Things we need to do before we recursively start building the kernel
# or the modules are listed in "prepare-all".
# A multi level approach is used. prepare1 is updated first, then prepare0.
# prepare-all is the collection point for the prepare targets.
# or the modules are listed in "prepare".
# A multi level approach is used. prepareN is processed before prepareN-1.
# archprepare is used in arch Makefiles and when processed asm symlink,
# version.h and scripts_basic is processed / created.
.PHONY: prepare-all prepare prepare0 prepare1 prepare2
# Listed in dependency order
.PHONY: prepare archprepare prepare0 prepare1 prepare2 prepare3
# prepare2 is used to check if we are building in a separate output directory,
# prepare-all is deprecated, use prepare as valid replacement
.PHONY: prepare-all
# prepare3 is used to check if we are building in a separate output directory,
# and if so do:
# 1) Check that make has not been executed in the kernel src $(srctree)
# 2) Create the include2 directory, used for the second asm symlink
prepare2:
prepare3:
ifneq ($(KBUILD_SRC),)
@echo ' Using $(srctree) as source for kernel'
$(Q)if [ -f $(srctree)/.config ]; then \
@ -795,18 +809,23 @@ ifneq ($(KBUILD_SRC),)
$(Q)ln -fsn $(srctree)/include/asm-$(ARCH) include2/asm
endif
# prepare1 creates a makefile if using a separate output directory
prepare1: prepare2 outputmakefile
# prepare2 creates a makefile if using a separate output directory
prepare2: prepare3 outputmakefile
prepare0: prepare1 include/linux/version.h include/asm \
prepare1: prepare2 include/linux/version.h include/asm \
include/config/MARKER
ifneq ($(KBUILD_MODULES),)
$(Q)rm -rf $(MODVERDIR)
$(Q)mkdir -p $(MODVERDIR)
endif
archprepare: prepare1 scripts_basic
prepare0: archprepare FORCE
$(Q)$(MAKE) $(build)=.
# All the preparing..
prepare-all: prepare0 prepare
prepare prepare-all: prepare0
# Leave this as default for preprocessing vmlinux.lds.S, which is now
# done in arch/$(ARCH)/kernel/Makefile
@ -845,7 +864,7 @@ include/asm:
# Split autoconf.h into include/linux/config/*
include/config/MARKER: include/linux/autoconf.h
include/config/MARKER: scripts/basic/split-include include/linux/autoconf.h
@echo ' SPLIT include/linux/autoconf.h -> include/config/*'
@scripts/basic/split-include include/linux/autoconf.h include/config
@touch $@
@ -897,7 +916,7 @@ modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux)
# Target to prepare building external modules
.PHONY: modules_prepare
modules_prepare: prepare-all scripts
modules_prepare: prepare scripts
# Target to install modules
.PHONY: modules_install
@ -949,26 +968,6 @@ modules modules_install: FORCE
endif # CONFIG_MODULES
# Generate asm-offsets.h
# ---------------------------------------------------------------------------
define filechk_gen-asm-offsets
(set -e; \
echo "#ifndef __ASM_OFFSETS_H__"; \
echo "#define __ASM_OFFSETS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by arch/$(ARCH)/Makefile"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne "/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"; \
echo ""; \
echo "#endif" )
endef
###
# Cleaning is done on three levels.
# make clean Delete most generated files
@ -991,7 +990,7 @@ MRPROPER_FILES += .config .config.old include/asm .version \
#
clean: rm-dirs := $(CLEAN_DIRS)
clean: rm-files := $(CLEAN_FILES)
clean-dirs := $(addprefix _clean_,$(vmlinux-alldirs))
clean-dirs := $(addprefix _clean_,$(srctree) $(vmlinux-alldirs))
.PHONY: $(clean-dirs) clean archclean
$(clean-dirs):
@ -1070,6 +1069,7 @@ help:
@echo ' rpm - Build a kernel as an RPM package'
@echo ' tags/TAGS - Generate tags file for editors'
@echo ' cscope - Generate cscope index'
@echo ' kernelrelease - Output the release version string'
@echo ''
@echo 'Static analysers'
@echo ' buildcheck - List dangling references to vmlinux discarded sections'

14
REPORTING-BUGS
View file

@ -9,7 +9,7 @@ screen please read "Documentation/oops-tracing.txt" before posting your
bug report. This explains what you should do with the "Oops" information
to make it useful to the recipient.
Send the output the maintainer of the kernel area that seems to
Send the output to the maintainer of the kernel area that seems to
be involved with the problem. Don't worry too much about getting the
wrong person. If you are unsure send it to the person responsible for the
code relevant to what you were doing. If it occurs repeatably try and
@ -18,15 +18,15 @@ The list of maintainers is in the MAINTAINERS file in this directory.
If it is a security bug, please copy the Security Contact listed
in the MAINTAINERS file. They can help coordinate bugfix and disclosure.
See Documentation/SecurityBugs for more infomation.
See Documentation/SecurityBugs for more information.
If you are totally stumped as to whom to send the report, send it to
linux-kernel@vger.kernel.org. (For more information on the linux-kernel
mailing list see http://www.tux.org/lkml/).
This is a suggested format for a bug report sent to the Linux kernel mailing
list. Having a standardized bug report form makes it easier for you not to
overlook things, and easier for the developers to find the pieces of
This is a suggested format for a bug report sent to the Linux kernel mailing
list. Having a standardized bug report form makes it easier for you not to
overlook things, and easier for the developers to find the pieces of
information they're really interested in. Don't feel you have to follow it.
First run the ver_linux script included as scripts/ver_linux, which
@ -35,9 +35,9 @@ the command "sh scripts/ver_linux".
Use that information to fill in all fields of the bug report form, and
post it to the mailing list with a subject of "PROBLEM: <one line
summary from [1.]>" for easy identification by the developers
summary from [1.]>" for easy identification by the developers.
[1.] One line summary of the problem:
[1.] One line summary of the problem:
[2.] Full description of the problem/report:
[3.] Keywords (i.e., modules, networking, kernel):
[4.] Kernel version (from /proc/version):

11
arch/alpha/Makefile
View file

@ -108,20 +108,9 @@ $(boot)/vmlinux.gz: vmlinux
bootimage bootpfile bootpzfile: vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
prepare: include/asm-$(ARCH)/asm_offsets.h
arch/$(ARCH)/kernel/asm-offsets.s: include/asm include/linux/version.h \
include/config/MARKER
include/asm-$(ARCH)/asm_offsets.h: arch/$(ARCH)/kernel/asm-offsets.s
$(call filechk,gen-asm-offsets)
archclean:
$(Q)$(MAKE) $(clean)=$(boot)
CLEAN_FILES += include/asm-$(ARCH)/asm_offsets.h
define archhelp
echo '* boot - Compressed kernel image (arch/alpha/boot/vmlinux.gz)'
echo ' bootimage - SRM bootable image (arch/alpha/boot/bootimage)'

9
arch/alpha/kernel/alpha_ksyms.c
View file

@ -185,15 +185,6 @@ EXPORT_SYMBOL(smp_num_cpus);
EXPORT_SYMBOL(smp_call_function);
EXPORT_SYMBOL(smp_call_function_on_cpu);
EXPORT_SYMBOL(_atomic_dec_and_lock);
#ifdef CONFIG_DEBUG_SPINLOCK
EXPORT_SYMBOL(_raw_spin_unlock);
EXPORT_SYMBOL(debug_spin_lock);
EXPORT_SYMBOL(debug_spin_trylock);
#endif
#ifdef CONFIG_DEBUG_RWLOCK
EXPORT_SYMBOL(_raw_write_lock);
EXPORT_SYMBOL(_raw_read_lock);
#endif
EXPORT_SYMBOL(cpu_present_mask);
#endif /* CONFIG_SMP */

2
arch/alpha/kernel/entry.S
View file

@ -5,7 +5,7 @@
*/
#include <linux/config.h>
#include <asm/asm_offsets.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/pal.h>
#include <asm/errno.h>

2
arch/alpha/kernel/head.S
View file

@ -9,7 +9,7 @@
#include <linux/config.h>
#include <asm/system.h>
#include <asm/asm_offsets.h>
#include <asm/asm-offsets.h>
.globl swapper_pg_dir
.globl _stext

8
arch/alpha/kernel/module.c
View file

@ -47,7 +47,7 @@ module_free(struct module *mod, void *module_region)
struct got_entry {
struct got_entry *next;
Elf64_Addr r_offset;
Elf64_Sxword r_addend;
int got_offset;
};
@ -57,14 +57,14 @@ process_reloc_for_got(Elf64_Rela *rela,
{
unsigned long r_sym = ELF64_R_SYM (rela->r_info);
unsigned long r_type = ELF64_R_TYPE (rela->r_info);
Elf64_Addr r_offset = rela->r_offset;
Elf64_Sxword r_addend = rela->r_addend;
struct got_entry *g;
if (r_type != R_ALPHA_LITERAL)
return;
for (g = chains + r_sym; g ; g = g->next)
if (g->r_offset == r_offset) {
if (g->r_addend == r_addend) {
if (g->got_offset == 0) {
g->got_offset = *poffset;
*poffset += 8;
@ -74,7 +74,7 @@ process_reloc_for_got(Elf64_Rela *rela,
g = kmalloc (sizeof (*g), GFP_KERNEL);
g->next = chains[r_sym].next;
g->r_offset = r_offset;
g->r_addend = r_addend;
g->got_offset = *poffset;
*poffset += 8;
chains[r_sym].next = g;

7
arch/alpha/kernel/osf_sys.c
View file

@ -974,6 +974,7 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp,
size_t size;
long timeout;
int ret = -EINVAL;
struct fdtable *fdt;
timeout = MAX_SCHEDULE_TIMEOUT;
if (tvp) {
@ -995,7 +996,8 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp,
}
}
if (n < 0 || n > current->files->max_fdset)
fdt = files_fdtable(current->files);
if (n < 0 || n > fdt->max_fdset)
goto out_nofds;
/*
@ -1152,8 +1154,7 @@ osf_usleep_thread(struct timeval32 __user *sleep, struct timeval32 __user *remai
ticks = timeval_to_jiffies(&tmp);
current->state = TASK_INTERRUPTIBLE;
ticks = schedule_timeout(ticks);
ticks = schedule_timeout_interruptible(ticks);
if (remain) {
jiffies_to_timeval(ticks, &tmp);

172
arch/alpha/kernel/smp.c
View file

@ -989,175 +989,3 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
preempt_enable();
}
#ifdef CONFIG_DEBUG_SPINLOCK
void
_raw_spin_unlock(spinlock_t * lock)
{
mb();
lock->lock = 0;
lock->on_cpu = -1;
lock->previous = NULL;
lock->task = NULL;
lock->base_file = "none";
lock->line_no = 0;
}
void
debug_spin_lock(spinlock_t * lock, const char *base_file, int line_no)
{
long tmp;
long stuck;
void *inline_pc = __builtin_return_address(0);
unsigned long started = jiffies;
int printed = 0;
int cpu = smp_processor_id();
stuck = 1L << 30;
try_again:
/* Use sub-sections to put the actual loop at the end
of this object file's text section so as to perfect
branch prediction. */
__asm__ __volatile__(
"1: ldl_l %0,%1\n"
" subq %2,1,%2\n"
" blbs %0,2f\n"
" or %0,1,%0\n"
" stl_c %0,%1\n"
" beq %0,3f\n"
"4: mb\n"
".subsection 2\n"
"2: ldl %0,%1\n"
" subq %2,1,%2\n"
"3: blt %2,4b\n"
" blbs %0,2b\n"
" br 1b\n"
".previous"
: "=r" (tmp), "=m" (lock->lock), "=r" (stuck)
: "m" (lock->lock), "2" (stuck) : "memory");
if (stuck < 0) {
printk(KERN_WARNING
"%s:%d spinlock stuck in %s at %p(%d)"
" owner %s at %p(%d) %s:%d\n",
base_file, line_no,
current->comm, inline_pc, cpu,
lock->task->comm, lock->previous,
lock->on_cpu, lock->base_file, lock->line_no);
stuck = 1L << 36;
printed = 1;
goto try_again;
}
/* Exiting. Got the lock. */
lock->on_cpu = cpu;
lock->previous = inline_pc;
lock->task = current;
lock->base_file = base_file;
lock->line_no = line_no;
if (printed) {
printk(KERN_WARNING
"%s:%d spinlock grabbed in %s at %p(%d) %ld ticks\n",
base_file, line_no, current->comm, inline_pc,
cpu, jiffies - started);
}
}
int
debug_spin_trylock(spinlock_t * lock, const char *base_file, int line_no)
{
int ret;
if ((ret = !test_and_set_bit(0, lock))) {
lock->on_cpu = smp_processor_id();
lock->previous = __builtin_return_address(0);
lock->task = current;
} else {
lock->base_file = base_file;
lock->line_no = line_no;
}
return ret;
}
#endif /* CONFIG_DEBUG_SPINLOCK */
#ifdef CONFIG_DEBUG_RWLOCK
void _raw_write_lock(rwlock_t * lock)
{
long regx, regy;
int stuck_lock, stuck_reader;
void *inline_pc = __builtin_return_address(0);
try_again:
stuck_lock = 1<<30;
stuck_reader = 1<<30;
__asm__ __volatile__(
"1: ldl_l %1,%0\n"
" blbs %1,6f\n"
" blt %1,8f\n"
" mov 1,%1\n"
" stl_c %1,%0\n"
" beq %1,6f\n"
"4: mb\n"
".subsection 2\n"
"6: blt %3,4b # debug\n"
" subl %3,1,%3 # debug\n"
" ldl %1,%0\n"
" blbs %1,6b\n"
"8: blt %4,4b # debug\n"
" subl %4,1,%4 # debug\n"
" ldl %1,%0\n"
" blt %1,8b\n"
" br 1b\n"
".previous"
: "=m" (*(volatile int *)lock), "=&r" (regx), "=&r" (regy),
"=&r" (stuck_lock), "=&r" (stuck_reader)
: "m" (*(volatile int *)lock), "3" (stuck_lock), "4" (stuck_reader) : "memory");
if (stuck_lock < 0) {
printk(KERN_WARNING "write_lock stuck at %p\n", inline_pc);
goto try_again;
}
if (stuck_reader < 0) {
printk(KERN_WARNING "write_lock stuck on readers at %p\n",
inline_pc);
goto try_again;
}
}
void _raw_read_lock(rwlock_t * lock)
{
long regx;
int stuck_lock;
void *inline_pc = __builtin_return_address(0);
try_again:
stuck_lock = 1<<30;
__asm__ __volatile__(
"1: ldl_l %1,%0;"
" blbs %1,6f;"
" subl %1,2,%1;"
" stl_c %1,%0;"
" beq %1,6f;"
"4: mb\n"
".subsection 2\n"
"6: ldl %1,%0;"
" blt %2,4b # debug\n"
" subl %2,1,%2 # debug\n"
" blbs %1,6b;"
" br 1b\n"
".previous"
: "=m" (*(volatile int *)lock), "=&r" (regx), "=&r" (stuck_lock)
: "m" (*(volatile int *)lock), "2" (stuck_lock) : "memory");
if (stuck_lock < 0) {
printk(KERN_WARNING "read_lock stuck at %p\n", inline_pc);
goto try_again;
}
}
#endif /* CONFIG_DEBUG_RWLOCK */

2
arch/alpha/lib/dbg_stackcheck.S
View file

@ -5,7 +5,7 @@
* Verify that we have not overflowed the stack. Oops if we have.
*/
#include <asm/asm_offsets.h>
#include <asm/asm-offsets.h>
.text
.set noat

2
arch/alpha/lib/dbg_stackkill.S
View file

@ -6,7 +6,7 @@
* uninitialized local variables in the act.
*/
#include <asm/asm_offsets.h>
#include <asm/asm-offsets.h>
.text
.set noat

4
arch/arm/Kconfig
View file

@ -326,8 +326,8 @@ config SMP
processor machines. On a single processor machine, the kernel will
run faster if you say N here.
See also the <file:Documentation/smp.tex>,
<file:Documentation/smp.txt>, <file:Documentation/i386/IO-APIC.txt>,
See also the <file:Documentation/smp.txt>,
<file:Documentation/i386/IO-APIC.txt>,
<file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
<http://www.linuxdoc.org/docs.html#howto>.

2
arch/arm/Kconfig.debug
View file

@ -53,7 +53,7 @@ config DEBUG_LL
bool "Kernel low-level debugging functions"
depends on DEBUG_KERNEL
help
Say Y here to include definitions of printascii, printchar, printhex
Say Y here to include definitions of printascii, printch, printhex
in the kernel. This is helpful if you are debugging code that
executes before the console is initialized.

11
arch/arm/Makefile
View file

@ -175,10 +175,10 @@ else
endif
@touch $@
prepare: maketools include/asm-arm/.arch
archprepare: maketools include/asm-arm/.arch
.PHONY: maketools FORCE
maketools: include/asm-arm/constants.h include/linux/version.h FORCE
maketools: include/linux/version.h FORCE
$(Q)$(MAKE) $(build)=arch/arm/tools include/asm-arm/mach-types.h
# Convert bzImage to zImage
@ -190,7 +190,7 @@ zImage Image xipImage bootpImage uImage: vmlinux
zinstall install: vmlinux
$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $@
CLEAN_FILES += include/asm-arm/constants.h* include/asm-arm/mach-types.h \
CLEAN_FILES += include/asm-arm/mach-types.h \
include/asm-arm/arch include/asm-arm/.arch
# We use MRPROPER_FILES and CLEAN_FILES now
@ -201,11 +201,6 @@ archclean:
bp:; $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/bootpImage
i zi:; $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $@
arch/$(ARCH)/kernel/asm-offsets.s: include/asm include/linux/version.h \
include/asm-arm/.arch
include/asm-$(ARCH)/constants.h: arch/$(ARCH)/kernel/asm-offsets.s
$(call filechk,gen-asm-offsets)
define archhelp
echo '* zImage - Compressed kernel image (arch/$(ARCH)/boot/zImage)'

2
arch/arm/common/scoop.c
View file

@ -91,7 +91,7 @@ EXPORT_SYMBOL(read_scoop_reg);
EXPORT_SYMBOL(write_scoop_reg);
#ifdef CONFIG_PM
static int scoop_suspend(struct device *dev, uint32_t state, uint32_t level)
static int scoop_suspend(struct device *dev, pm_message_t state, uint32_t level)
{
if (level == SUSPEND_POWER_DOWN) {
struct scoop_dev *sdev = dev_get_drvdata(dev);

5
arch/arm/kernel/calls.S
View file

@ -10,7 +10,7 @@
* This file is included twice in entry-common.S
*/
#ifndef NR_syscalls
#define NR_syscalls 320
#define NR_syscalls 328
#else
__syscall_start:
@ -333,6 +333,9 @@ __syscall_start:
.long sys_inotify_init
.long sys_inotify_add_watch
.long sys_inotify_rm_watch
.long sys_mbind_wrapper
/* 320 */ .long sys_get_mempolicy
.long sys_set_mempolicy
__syscall_end:
.rept NR_syscalls - (__syscall_end - __syscall_start) / 4

4
arch/arm/kernel/entry-common.S
View file

@ -269,6 +269,10 @@ sys_arm_fadvise64_64_wrapper:
str r5, [sp, #4] @ push r5 to stack
b sys_arm_fadvise64_64
sys_mbind_wrapper:
str r5, [sp, #4]
b sys_mbind
/*
* Note: off_4k (r5) is always units of 4K. If we can't do the requested
* offset, we return EINVAL.

2
arch/arm/kernel/entry-header.S
View file

@ -3,7 +3,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/errno.h>
#include <asm/thread_info.h>

2
arch/arm/kernel/head.S
View file

@ -20,7 +20,7 @@
#include <asm/mach-types.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/system.h>

2
arch/arm/kernel/iwmmxt.S
View file

@ -17,7 +17,7 @@
#include <linux/linkage.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#define MMX_WR0 (0x00)
#define MMX_WR1 (0x08)

2
arch/arm/lib/copy_page.S
View file

@ -11,7 +11,7 @@
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#define COPY_COUNT (PAGE_SZ/64 PLD( -1 ))

2
arch/arm/lib/csumpartialcopyuser.S
View file

@ -13,7 +13,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
.text

2
arch/arm/lib/getuser.S
View file

@ -26,7 +26,7 @@
* Note that ADDR_LIMIT is either 0 or 0xc0000000.
* Note also that it is intended that __get_user_bad is not global.
*/
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/errno.h>

2
arch/arm/lib/putuser.S
View file

@ -26,7 +26,7 @@
* Note that ADDR_LIMIT is either 0 or 0xc0000000
* Note also that it is intended that __put_user_bad is not global.
*/
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/errno.h>

28
arch/arm/mach-pxa/corgi.c
View file

@ -131,27 +131,12 @@ static struct platform_device corgits_device = {
/*
* MMC/SD Device
*
* The card detect interrupt isn't debounced so we delay it by HZ/4
* The card detect interrupt isn't debounced so we delay it by 250ms
* to give the card a chance to fully insert/eject.
*/
static struct mmc_detect {
struct timer_list detect_timer;
void *devid;
} mmc_detect;
static struct pxamci_platform_data corgi_mci_platform_data;
static void mmc_detect_callback(unsigned long data)
{
mmc_detect_change(mmc_detect.devid);
}
static irqreturn_t corgi_mmc_detect_int(int irq, void *devid, struct pt_regs *regs)
{
mmc_detect.devid=devid;
mod_timer(&mmc_detect.detect_timer, jiffies + HZ/4);
return IRQ_HANDLED;
}
static int corgi_mci_init(struct device *dev, irqreturn_t (*unused_detect_int)(int, void *, struct pt_regs *), void *data)
static int corgi_mci_init(struct device *dev, irqreturn_t (*corgi_detect_int)(int, void *, struct pt_regs *), void *data)
{
int err;
@ -161,11 +146,9 @@ static int corgi_mci_init(struct device *dev, irqreturn_t (*unused_detect_int)(i
pxa_gpio_mode(CORGI_GPIO_nSD_DETECT | GPIO_IN);
pxa_gpio_mode(CORGI_GPIO_SD_PWR | GPIO_OUT);
init_timer(&mmc_detect.detect_timer);
mmc_detect.detect_timer.function = mmc_detect_callback;
mmc_detect.detect_timer.data = (unsigned long) &mmc_detect;
corgi_mci_platform_data.detect_delay = msecs_to_jiffies(250);
err = request_irq(CORGI_IRQ_GPIO_nSD_DETECT, corgi_mmc_detect_int, SA_INTERRUPT,
err = request_irq(CORGI_IRQ_GPIO_nSD_DETECT, corgi_detect_int, SA_INTERRUPT,
"MMC card detect", data);
if (err) {
printk(KERN_ERR "corgi_mci_init: MMC/SD: can't request MMC card detect IRQ\n");
@ -198,7 +181,6 @@ static int corgi_mci_get_ro(struct device *dev)
static void corgi_mci_exit(struct device *dev, void *data)
{
free_irq(CORGI_IRQ_GPIO_nSD_DETECT, data);
del_timer(&mmc_detect.detect_timer);
}
static struct pxamci_platform_data corgi_mci_platform_data = {

2
arch/arm/mach-pxa/corgi_ssp.c
View file

@ -22,7 +22,7 @@
#include <asm/arch/corgi.h>
#include <asm/arch/pxa-regs.h>
static spinlock_t corgi_ssp_lock = SPIN_LOCK_UNLOCKED;
static DEFINE_SPINLOCK(corgi_ssp_lock);
static struct ssp_dev corgi_ssp_dev;
static struct ssp_state corgi_ssp_state;

11
arch/arm/mach-s3c2410/devs.c
View file

@ -29,7 +29,7 @@
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <asm/mach/irq.h>
#include <asm/arch/fb.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
@ -103,6 +103,15 @@ struct platform_device s3c_device_lcd = {
EXPORT_SYMBOL(s3c_device_lcd);
static struct s3c2410fb_mach_info s3c2410fb_info;
void __init set_s3c2410fb_info(struct s3c2410fb_mach_info *hard_s3c2410fb_info)
{
memcpy(&s3c2410fb_info,hard_s3c2410fb_info,sizeof(struct s3c2410fb_mach_info));
s3c_device_lcd.dev.platform_data = &s3c2410fb_info;
}
EXPORT_SYMBOL(set_s3c2410fb_info);
/* NAND Controller */
static struct resource s3c_nand_resource[] = {

51
arch/arm/mach-s3c2410/mach-h1940.c
View file

@ -45,6 +45,9 @@
//#include <asm/debug-ll.h>
#include <asm/arch/regs-serial.h>
#include <asm/arch/regs-lcd.h>
#include <asm/arch/fb.h>
#include <linux/serial_core.h>
@ -88,6 +91,48 @@ static struct s3c2410_uartcfg h1940_uartcfgs[] = {
/**
* Set lcd on or off
**/
static struct s3c2410fb_mach_info h1940_lcdcfg __initdata = {
.fixed_syncs= 1,
.regs={
.lcdcon1= S3C2410_LCDCON1_TFT16BPP | \
S3C2410_LCDCON1_TFT | \
S3C2410_LCDCON1_CLKVAL(0x0C),
.lcdcon2= S3C2410_LCDCON2_VBPD(7) | \
S3C2410_LCDCON2_LINEVAL(319) | \
S3C2410_LCDCON2_VFPD(6) | \
S3C2410_LCDCON2_VSPW(0),
.lcdcon3= S3C2410_LCDCON3_HBPD(19) | \
S3C2410_LCDCON3_HOZVAL(239) | \
S3C2410_LCDCON3_HFPD(7),
.lcdcon4= S3C2410_LCDCON4_MVAL(0) | \
S3C2410_LCDCON4_HSPW(3),
.lcdcon5= S3C2410_LCDCON5_FRM565 | \
S3C2410_LCDCON5_INVVLINE | \
S3C2410_LCDCON5_HWSWP,
},
.lpcsel= 0x02,
.gpccon= 0xaa940659,
.gpccon_mask= 0xffffffff,
.gpcup= 0x0000ffff,
.gpcup_mask= 0xffffffff,
.gpdcon= 0xaa84aaa0,
.gpdcon_mask= 0xffffffff,
.gpdup= 0x0000faff,
.gpdup_mask= 0xffffffff,
.width= 240,
.height= 320,
.xres= {240,240,240},
.yres= {320,320,320},
.bpp= {16,16,16},
};
static struct platform_device *h1940_devices[] __initdata = {
&s3c_device_usb,
@ -116,6 +161,11 @@ void __init h1940_init_irq(void)
}
void __init h1940_init(void)
{
set_s3c2410fb_info(&h1940_lcdcfg);
}
MACHINE_START(H1940, "IPAQ-H1940")
/* Maintainer: Ben Dooks <ben@fluff.org> */
.phys_ram = S3C2410_SDRAM_PA,
@ -124,5 +174,6 @@ MACHINE_START(H1940, "IPAQ-H1940")
.boot_params = S3C2410_SDRAM_PA + 0x100,
.map_io = h1940_map_io,
.init_irq = h1940_init_irq,
.init_machine = h1940_init,
.timer = &s3c24xx_timer,
MACHINE_END

2
arch/arm/mm/copypage-v3.S
View file

@ -12,7 +12,7 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
.text
.align 5

2
arch/arm/mm/copypage-v4wb.S
View file

@ -11,7 +11,7 @@
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
.text
.align 5

2
arch/arm/mm/copypage-v4wt.S
View file

@ -14,7 +14,7 @@
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
.text
.align 5

2
arch/arm/mm/proc-arm1020.S
View file

@ -28,7 +28,7 @@
#include <linux/config.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-arm1020e.S
View file

@ -28,7 +28,7 @@
#include <linux/config.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-arm1022.S
View file

@ -17,7 +17,7 @@
#include <linux/config.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-arm1026.S
View file

@ -17,7 +17,7 @@
#include <linux/config.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-arm6_7.S
View file

@ -13,7 +13,7 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-arm720.S
View file

@ -33,7 +33,7 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/procinfo.h>
#include <asm/ptrace.h>

2
arch/arm/mm/proc-macros.S
View file

@ -4,7 +4,7 @@
* VMA_VM_FLAGS
* VM_EXEC
*/
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
/*

2
arch/arm/mm/proc-sa110.S
View file

@ -15,7 +15,7 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/procinfo.h>
#include <asm/hardware.h>
#include <asm/pgtable.h>

2
arch/arm/mm/proc-sa1100.S
View file

@ -20,7 +20,7 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/constants.h>
#include <asm/asm-offsets.h>
#include <asm/procinfo.h>
#include <asm/hardware.h>
#include <asm/pgtable.h>

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