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SubjectRe: [PATCH] xen: core dom0 support
Jeremy Fitzhardinge wrote:
> H. Peter Anvin wrote:
>> In this particular case, this is actually false. "No PAT" in the
>> processor is *not* the same thing as "no cacheability controls in the
>> page tables". Every processor since the 386 has had UC, WT, and WB
>> controls in the page tables; PAT only added the ability to do WC (and
>> WP, which we don't use). Since the number of processors which can do
>> WC at all but don't have PAT is a small set of increasingly obsolete
>> processors, we may very well choose to simply ignore the WC
>> capabilities of these particular processors.
>
> I'm not quite sure what you're referring to with "this is actually
> false". Certainly we support cachability control in ptes under Xen. We
> just don't support full PAT because Xen uses PAT for itself.
>

What do you define as "full PAT"? If what you mean is that Xen lays
claims to the PAT MSR and only allows a certain mapping that's hardly a
problem... other than that it's not an exhaustible resource so I guess I
really don't understand what you're trying to say here.

-hpa


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