Re: [PATCH] xen: core dom0 support
From: Jeremy Fitzhardinge
Date: Sun Mar 01 2009 - 19:08:52 EST
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.
J
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