Re: [PATCH 1/5] x86, mm, pat: Set WT to PA4 slot of PAT MSR

From: Toshi Kani
Date: Fri Sep 05 2014 - 11:33:28 EST


On Fri, 2014-09-05 at 08:07 -0700, H. Peter Anvin wrote:
> On 09/05/2014 07:00 AM, Toshi Kani wrote:
> >
> > That's a fine idea, but as Ingo also suggested, I am going to disable
> > this feature on all Pentium 4 models. That should give us a safety
> > margin. Using slot 4 has a benefit that it keeps the PAT setup
> > consistent with Xen.
> >
>
> Slot 4 is also the maximally problematic one, because it is the one that
> might be incorrectly invoked for the page tables themselves.

Good point. I wonder if Xen folks feel strongly about keeping the PAT
setup consistent with the kernel. If not, we may choose to use slot 6
(or 7).

Thanks,
-Toshi

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