From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <jbeulich@novell.com>
Subject: Re: mapping of memory below 16Mb
Date: Thu, 24 Jan 2008 16:24:08 +0000
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	<C3BE5EAE.1B616%Keir.Fraser@cl.cam.ac.uk>
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To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
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>> The WP attribute raises another question: Are there any plans to make
>> Xen use PAT rather than (relying on) MTRRs? Linux folks seem to be
>> finally getting closer to this, too, so even virtual PAT support may be
>> needed in not too distant future...
>
>We already support PAT for both PV guests and HVM guests.

Oh, and my understanding of PAT support goes beyond just setting the
PAT MSR and adjusting page table flags. Specifically, if we have PAT we
should never need to modify MTRRs, which would eliminate conflicts on
updates of those that I'm seeing on various boxes, always just
depending on how BIOS sets them up, and always related to overlaps
of the video memory with existing MTRR ranges.

Jan