To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Avuton Olrich <avuton@gmail.com>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: Kernel panic: Machine check exception
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	<3aa654a40511191254x4bf50cc8l6a9b8786f1a5ebc8@mail.gmail.com>
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From: ebiederm@xmission.com (Eric W. Biederman)
Date: Tue, 06 Dec 2005 04:13:24 -0700
In-Reply-To: <1132436886.19692.17.camel@localhost.localdomain> (Alan Cox's
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> On Sad, 2005-11-19 at 12:54 -0800, Avuton Olrich wrote:
>> Is there a good way to narrow it down? I guess running a badmem
>> program would be good to start with, otherwise ...(?).
>
> A memory test may be worth doing but most machine checks indicate the
> fault is more serious than bad memory.

Although on the Opteron that is usually what it is (as memory
errors can be reported through the machine check interface)

In this case bank 4 is the appropriate bank.  Although the
other bits don't look right for a memory error.  I wonder
if it is that darn iommu fault again.

To decode an Opteron machine_check you can look in
the bios and kernel programmers guide.  (Possibly the
architecture but I think that is too generic) to see
what all of the bits mean.

It is a pain but is faster than poking blindly in
the dark.

Eric
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