linux-kernel - Re: AMD FX CPU bug, not fixed by latest microcode?

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Date:	Mon, 11 Jun 2012 13:05:57 +0200
From:	Johannes Stezenbach <js@...21.net>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Boszormenyi Zoltan <zboszor@...hu>, linux-kernel@...r.kernel.org,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: AMD FX CPU bug, not fixed by latest microcode?

On Mon, Jun 11, 2012 at 11:49:05AM +0200, Borislav Petkov wrote:
> On Mon, Jun 11, 2012 at 10:43:18AM +0200, Borislav Petkov wrote:
> > On Sun, Jun 10, 2012 at 09:24:13PM +0200, Boszormenyi Zoltan wrote:
> > > I have an AMD FX-8120 boxed CPU in an ASUS M5A99X-EVO mainboard
> > > with 32GB DDR3/1600 memory, running Fedora 17, upgraded from 16.
> > > memtest86+ show no problems.
> 
> Ohe other thing: if there's an option in the BIOS to disable the IOMMU,
> can you do that and try reproducing the issue with IOMMU disabled?

Maybe not related, but I had bad memory in my Intel Core-i5
based system some months ago which resulted in rare crashes,
usually manifested itself as g++ ICEs when compiling a
mid-sized  C++ project -- compiling a kernel with make -p4 showed
no problem.  Also memtest86+ didn't show the issue,
so I tried memtest86-4.0a which claims to find more errors
due to SMP support.  An overnight run left me with a screen
full of garbage and a crashed memtest86-4.0.  I replaced
the RAM anyway and the box was stable since then.

memtest86-4.0a is at
http://memtest86.com/

The page claims:
  With a single CPU it is not possible to drive multi-channel memory
  controllers at full speed making it impossible to detect some types of errors

Maybe someone knowledgable could comment if this is true.

Johannes
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