Make the hardware perceive the RX descriptor ring as a null-terminated linked
list, instead of a circular ring.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add some debugging and error printing.
The show_rx_chain() prints out the status of the rx chain,
which shows that the status of the descriptors gets
messed up after the second & subsequent RX ramfulls.
Print out contents of bad packets if error occurs.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Delete possible source of chain corruption; the hardware
already knows the location of the tail, and writing it
again is likely to mess it up.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add memory barrier to make sure that the rest of the
RX descriptor state is flushed to memory before we tell
the hardware that its ready to go.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Tell the hardware the location of the rx ring tail.
More punctuation cleanup.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Remove unused variable; this makes code easier to read.
Tweak commentary.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The invocation of the rx ring refill routine is haphazard,
it can be called from a central location.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Simplify the somewhat convoluted use of return codes
in the rx buffer handling.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Another skb leak in an error branch. Fix this by adding
call to dev_kfree_skb_irq() after moving to a more
appropriate spot.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
One of the unlikely error branches has an skb memory leak.
Fix this by handling the error conditions consistently.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
There is no need to pass a flag into spider_net_decode_one_descr()
so remove this, and perform some othre minor cleanup.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Get rid of the rxramfull tasklet, and let the NAPI poll routine
deal with this situation. (The rxramfull interrupt is simply
stating that the h/w has run out of room for incoming packets).
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds net_ratelimit to many of the printks in order to
limit extraneous warning messages (created in response to Bug 28554).
This patch supercedes all previous ratelimit patches.
This has been tested, please apply.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <jlinas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The current driver code performs 512 DMA mappings of a bunch of
32-byte ring descriptor structures. This is silly, as they are
all in contiguous memory. This patch changes the code to
dma_map_coherent() each rx/tx ring as a whole.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
We forget to call spider_net_free_rx_chain_contents which does the
actual dev_kfree_skb. New skbs are allocated from skbuff_head_cache
on each "ifconfig up" letting the cache grow infinitely.
This patch fixes it.
Signed-off-by: Jens Osterkamp <jens@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Conflicts:
drivers/ata/libata-scsi.c
include/linux/libata.h
Futher merge of Linus's head and compilation fixups.
Signed-Off-By: David Howells <dhowells@redhat.com>
Conflicts:
drivers/infiniband/core/iwcm.c
drivers/net/chelsio/cxgb2.c
drivers/net/wireless/bcm43xx/bcm43xx_main.c
drivers/net/wireless/prism54/islpci_eth.c
drivers/usb/core/hub.h
drivers/usb/input/hid-core.c
net/core/netpoll.c
Fix up merge failures with Linus's head and fix new compilation failures.
Signed-Off-By: David Howells <dhowells@redhat.com>
We use the powerpc specific low level MMIO accessor variants instead
of readl() or readl_be() because we know spidernet is not a real PCI
device and we can thus avoid the performance hit caused by the PCI
workarounds.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Correct a problem seen on later kernels running the NetPIPE application.
Specifically, NetPIPE would begin running very slowly at the 1533 packet
size. It was determined that Spidernet slowed with an idle DMA engine.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
In an earlier patch, code was added to pad packets that were less that
ETH_ZLEN (60) bytes using the skb_pad function. This has caused hangs when
accessing certain NFS mounted file systems. This patch removes the check
and solves the NFS problem. The driver, with this patch, has been tested
extensively. Please apply.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Cc: Stephen Hemminger <shemminger@osdl.org>
Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Bugfix: rx descriptor release function fails to visit
the last entry while walking receive descriptor ring.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The ring buffer descriptors are DMA-accessed bidirectionally,
but are not declared in this way. Fix this.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Cosmetic patch: give the variable holding the numer of descriptors
a more descriptive name, so to avoid confusion.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The current code attempts to start the TX dma every time a packet
is queued. This is too conservative, and wastes CPU time. This
patch changes behaviour to call the kick-dma function less often,
only when the tx queue is at risk of emptying.
This reduces cpu usage, improves performance.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Remove a dummy register read that is not needed.
This reduces CPU usage notably during transmit.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The transmit side of the spider ethernet driver currently
places locks around some very large chunks of code. This
results in a fair amount of lock contention is some cases.
This patch makes the locks much more fine-grained, protecting
only the cirtical sections. One lock is used to protect
three locations: the queue head and tail pointers, and the
queue low-watermark location.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch moves transmit queue cleanup code out of the
interrupt context, and into the NAPI polling routine.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Implement basic low-watermark support for the transmit queue.
Hardware low-watermarks allow a properly configured kernel
to continously stream data to a device and not have to handle
any interrupts at all in doing so. Correct zero-interrupt
operation can be actually observed for this driver, when the
socket buffer is made large enough.
The basic idea of a low-watermark interrupt is as follows.
The device driver queues up a bunch of packets for the hardware
to transmit, and then kicks the hardware to get it started.
As the hardware drains the queue of pending, untransmitted
packets, the device driver will want to know when the queue
is almost empty, so that it can queue some more packets.
If the queue drains down to the low waterark, then an interrupt
will be generated. However, if the kernel/driver continues
to add enough packets to keep the queue partially filled,
no interrupt will actually be generated, and the hardware
can continue streaming packets indefinitely in this mode.
The impelmentation is done by setting the DESCR_TXDESFLG flag
in one of the packets. When the hardware sees this flag, it will
interrupt the device driver. Because this flag is on a fixed
packet, rather than at fixed location in the queue, the
code below needs to move the flag as more packets are
queued up. This implementation attempts to keep the flag
at about 1/4 from "empty".
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Bugfix -- the rx chain is in memory after the tx chain --
the offset being used was wrong, resulting in memory corruption
when the size of the rx and tx rings weren't exactly the same.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Turn off mis-interpretation of the queue-empty interrupt
status bit as an error.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The print message associated with the descriptor chain end interrupt
prints a bogs value. Fix that.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds a call to netif_stop_queue() when there is
no more room for more packets on the transmit queue.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch fixes the names of a few fields in the DMA control
register. There is no functional change.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Set the netdev watchdog timer.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Polite device drivers pad short packets to 60 bytes,
so that mean-spirited users don't accidentally DOS
some other OS that can't handle short packets.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Bugfix: when cleaning up the transmit queue upon device close,
be sure to walk the entire queue.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The module param permsissions should bw read-only, not writable.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch adds version information as reported by
ethtool -i to the Spidernet driver.
From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
A driver shouldn't compare to DMA_ERROR_CODE directly, use
pci_dma_mapping_error() instead.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add the ethtool -S (show statistics) feature to the Spidernet ethernet
driver. I have tested it extensively and believe it is ready to be
applied.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Add ethtool -g (show ring sizes) support to the Spidernet network driver.
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Now that get_property() returns a void *, there's no need to cast its
return value. Also, treat the return value as const, so we can
constify get_property later.
powerpc-specific network device driver changes.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
With this patch TX queue descriptors are not chained per default any more.
The pointer to next descriptor is set only when next descriptor is prepaired
for transfer. Also the mechanism of checking wether Spider is ready has been
changed: it checks not for CARDOWNED flag in status of previous descriptor
but for a TXDMAENABLED flag in Spider's register.
Signed-off-by: Maxim Shchetynin <maxim@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
We want to intitialize addr instead of data register first.
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
A newer board revision changed the type of ethernet phy.
Moreover, this generalizes the way that a phy gets switched
into fiber mode when autodetection is not available.
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
We found a new chip setting that we need in order
to make the driver work more reliable.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
This enables TX checksum offloading for the spidernet driver by default.
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This patch reduces the message level of the RX ram full messages
from err to debug to prevent spamming the console leaving it in the
logfiles though.
From: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This is now required to avoid
drivers/net/spider_net.c:844: error: 'IPPROTO_TCP' undeclared
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Performance optimizations, changes in these areas:
- RX and TX checksum offload
- correct maximum MTU
- don't use TX interrupts anymore, use a timer instead
- remove some superfluous barriers
- improve RX RAM full handling
From: Utz Bacher <utz.bacher@de.ibm.com>
Signed-off-by: Jens Osterkamp <jens.osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
The driver incorrectly used dma_addr_t to describe
HW structures and consequently broke when that type
was changed in 2.6.15-rc.
This changed spidernet to use u32 for 32 bit HW defined
structure elements.
From: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
request_firmware() is sometimes problematic, especially
in initramfs, reading the firmware from Open Firmware
is much preferrable.
We still try to get the firmware from the file system
first, in order to support old SLOF releases and to allow
updates of the spidernet firmware without reflashing
the system.
From: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Uploading the device firmware may fail if wrong input data
was provided by the user. This checks for the condition.
From: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Jens Osterkamp <Jens.Osterkamp@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
This patch makes the driver work with any BladeCenter
network switch, it used to work only with certain
models.
Please apply.
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Another small update for the spidernet driver to fix a bug encountered
during testing our latest hardware with dual-ethernet support.
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
- Prevent PCI posting problems by using synchronous register access
in critical places
- Check return value from firmware device tree functions
- fix device cleanup
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
This patch adds a driver for a new 1000 Mbit ethernet NIC. It is
integrated on the south bridge that is used for our Cell Blades.
The code gets the MAC address from the Open Firmware device tree, so it
won't compile on platforms other than ppc64.
This is the first public release, so I don't expect the first version to
get merged, but I'd aim for integration within the 2.6.13 time frame.
Cc: Utz Bacher <utz.bacher@de.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
