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From: Pavel Roskin <proski@gnu.org>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] unaligned accesses
Date: Mon, 22 Mar 2010 17:49:34 -0400	[thread overview]
Message-ID: <1269294574.1237.114.camel@mj> (raw)
In-Reply-To: <40101cc31003221109t30343194x146c4c37a15a7119@mail.gmail.com>

On Mon, 2010-03-22 at 19:09 +0100, Matteo Croce wrote:
> I'm using ath9k on a MIPS platform, and the driver seems to do _lot_ of
> unaligned accesses, something like 270.000/sec

My first reaction was to reproduce it, but the only mips system I have
is a La Fonera router, which has no PCI.

I checked if it's possible to enable alignment checking on x86_64, but
it looks like gcc would use unaligned access on its own to initialize
data, so there will be massive false positives:

http://stackoverflow.com/questions/1929588/x86-howto-catch-data-alignment-faults-aka-sigbus-on-sparc

> u=$(cat /sys/kernel/debug/mips/unaligned_instructions)

I checked the sources for "unaligned_instructions" and found
"unaligned_action" nearby.  If set to 2 (UNALIGNED_ACTION_SHOW), it
would print registers, and then perhaps you could find the exact
location in the kernel.

-- 
Regards,
Pavel Roskin

  reply	other threads:[~2010-03-22 21:49 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-22 18:09 [ath9k-devel] unaligned accesses Matteo Croce
2010-03-22 21:49 ` Pavel Roskin [this message]
2010-03-22 23:22   ` Luca Niccoli
2010-03-23  0:18     ` Luca Niccoli
2010-03-23  7:03       ` Benoit PAPILLAULT

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