Messages in this thread | | | Date | Sun, 01 Mar 2009 16:46:48 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] xen: core dom0 support |
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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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