Re: PVH and mtrr/PAT.........

[George Dunlap <george.dunlap@eu.citrix.com>]

On 22/11/13 11:09, Jan Beulich wrote:
>>>> On 22.11.13 at 11:43, George Dunlap <george.dunlap@eu.citrix.com> 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.

OK -- so when we move forward with the plan of "PVH mode is HVM mode 
with a couple of tweaks", you think that we should have an "enable 
virtual MTRR" flag, and disable this for PVH mode?

  -George