Re: [PATCH] xen: core dom0 support

[H. Peter Anvin]

Jeremy Fitzhardinge wrote:
>>
>> 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.
> 
> It does not allow guests to set their own PAT MSRs.  It can't easily be
> multiplexed either, as all CPUs must have the same settings for their
> PAT MSRs.  I guess it could be handled by allowing domains to set their
> own virtual PAT MSRs, and then rewriting the ptes to convert from the
> guest PAT settings to Xen's, but I don't know if this is possible in
> general (and it poses some problems because the pte modifications would
> be guest-visible).
> 

It would make a lot more sense to simply specify a particular set of
mappings.  Since the only one anyone cares about that isn't in the
default set is WC anyway, it's easy to do.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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