Re: [Xen-devel] PVH and mtrr/PAT.........

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.11.13 at 11:43, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> I'm not incredibly familiar with the PAT / MTRR stuff, either from a 
> hardware level or a Xen level, so sorry if this is a dumb question. It 
> sounds like you're saying, because we have virtual MTRRs that are 
> already translated into EPT types, we should disable virtual MTRRs and 
> use PAT instead.  That doesn't make any kind of sense to me.  (I didn't 
> understand it when Jan said it either.)

The underlying observation is that MTRRs aren't really needed -
all they can do can be done with PAT. They pre-date PAT though,
hence hardware vendors can't easily drop them. But in a model
like PVH I just don't see the value of allowing their use, considering
that this adds unnecessary complexity.

Jan


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