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

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Message-ID: <4FD5C6C6.30000@ladisch.de>
Date:	Mon, 11 Jun 2012 12:21:58 +0200
From:	Clemens Ladisch <clemens@...isch.de>
To:	Boszormenyi Zoltan <zboszor@...hu>
CC:	linux-kernel@...r.kernel.org
Subject: Re: AMD FX CPU bug, not fixed by latest microcode?

Boszormenyi Zoltan wrote:
> 2012-06-11 09:52 keltezéssel, Clemens Ladisch írta:
>>> Similar errors happened during copying large files on the same
>>> machine but it seems it's enough to trigger if the total amount
>>> of data read is large enough.
>>
>> Does "large enough" mean "large enough so that they are not in the file
>> cache"?
>>
> "Large enough" means it's usually not in file system cache

If you could see a change while it's in the cache, you could rule
out the disks.

>> All caches and your memory are ECC protected,
>
> Unfortunately the memory is not with ECC.

Sorry, I misread your mail.

This means that you cannot rule out bad memory.

>> so I think it is unlikely
>> that the problem is with these.  If I had to guess, I'd point to your
>> disk (firmware) or the SATA controller.  (A bad or loose SATA cable
>> would throw CRC errors into the kernel log.  Are there any?)
>
> The disks (8 of them) are attached to 3ware 9650SE-8LPML in RAID10.
> tw_cli reports no problems.

Could you check whether the same happens with some disk connected to
the on-board SATA controller?  Or while copying around lots of data
inside a RAM disk?

>> What is the exact offset of the changed byte in the file?  (It might be
>> at a cacheline, sector, or page boundary.)
>
> The bad character is at offset 0x4b74.

That's completely random, i.e., probably an hardware error.

>> http://support.amd.com/us/Processor_TechDocs/48063_15h_Mod_00h-0Fh_Rev_Guide.pdf
>
> The "no fix planned" for every errata is saddening...

It's good news, because none of them actually matter.

Regards,
Clemens
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