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SubjectRE: 2.6.0-test3-mm1: scheduling while atomic (ext3?)
Date
See below.

] -Rich ...
] AMD Fellow
] richard.brunner at amd com

> From: Andi Kleen [mailto:ak@suse.de]

> On Wed, Aug 13, 2003 at 04:20:11PM +0100, Alan Cox wrote:
> > On Mer, 2003-08-13 at 15:20, Andi Kleen wrote:

> > Has AMD confirmed that your solution is ok for the K7 as well as K8 -
> > ie that if we hit the errata the fixup recovers the CPU from whatever
> > lunatic state it is now in ?
>
> My solution is a fix as the problem is described in the
> Opteron Specification Update (and also as our own testing
> showed - we discovered the problem originally)

Hi, AMD has not confirmed anything with respect to this issue
on K7/Athlon. We are currently trying to get the code that reproduces
this bug into AMD so we can see what triggers it.

Andi's workaround for Opteron (before a BIOS fix was available),
is probably a fine *short-term* workaround until we can get back
to you on this. AMD believes that dimissing a exception on
prefetch as spurious on Athlon will work you around the current
problem.

Linking the Opteron bug to an Athlon bug is pre-mature at this point.

> The Errata is basically: When there is a prefetch and a load for the
> same address in flight and the load faults and the CPU is in
> a very specific complicated state then the Exception is
> reported on the prefetch, not the fault.
>
> The fix just handles the exception and doesn't crash.
>
> At least on Opteron it can be also fixed with a magic bit in
> the BIOS, maybe that's possible on XP too. But I opted to
> work around it in the kernel to not force all people to get a
> new BIOS.

Let us get back to you, ok? I am starting up our
internal validation people to go poke at this.

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