Re: xfstests, bad generic tests 009 and 308

From: Dave Chinner <david@fromorbit.com>
To: Yann Dupont - Veille Techno <veilletechno-irts@univ-nantes.fr>
Cc: xfs@oss.sgi.com
Subject: Re: xfstests, bad generic tests 009 and 308
Date: Thu, 24 Sep 2015 08:04:44 +1000	[thread overview]
Message-ID: <20150923220444.GP19114@dastard> (raw)
In-Reply-To: <56028249.7040103@univ-nantes.fr>

On Wed, Sep 23, 2015 at 12:43:21PM +0200, Yann Dupont - Veille Techno wrote:
> Le 22/09/2015 00:52, Dave Chinner a écrit :
> >As it is, I highly recommend that you try a current 4.3 kernel, as
> >there are several code fixes in the XFS kernel code that work
> >around compiler issues we know about. AFAIA, the do_div() asm bug
> >that trips recent gcc optimisations isn't in the upstream kernel
> >yet, but that can be worked around by setting
> >CONFIG_CC_OPTIMIZE_FOR_SIZE=y in your build.
> 
> Hi dave,
> 
> I can confirm that CONFIG_CC_OPTIMIZE_FOR_SIZE=y is (was ?) the only
> way for me to have reliable XFS kernel code on different arm
> platforms (Marvell kirkwood, Allwinner A20, Amlogic S805), no matter
> what recent gcc version I've been using.
> 
> I must admit I was cross-compiling from X86-64 too, but I think (not
> sure) that it was also the case with native gcc.
> 
> I must also admit that I didn't tried since some months, because
> CONFIG_CC_OPTIMIZE_FOR_SIZE=y was the silver bullet for arm xfs
> kernel crashes. This crash was difficult to understand because it
> occurs quite randomly (I.e it can take several hours to trigger)
> 
> If there's a patch floating around for gcc (or kernel), I'm
> interested to test.

See this subthread from august:

http://oss.sgi.com/archives/xfs/2015-08/msg00234.html

AFAICT, the do_div patch to fix the problem has not yet been picked
up - it's not in the 4.3-rc2 kernel...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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