[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: The memory type of non-RAM address is WB by default?
On 23/10/08 11:01, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote: > Keir Fraser wrote: >> Why take any notice of guest MTRR/PAT in cases where the host knows >> better? >> > So we don't treat this warning as a bug and would not fix it. Correct? > I don't like warning. :-) Well, one approach would be not to warn! :-) Seriously: for anything which is not guest RAM, the host should really know best what memory type it should be mapped as (probably UC or WC). Hence why mess around validating a guest-requested memory type? The situation is different of course for guest RAM being used in non-WB contexts for device communications: in that case the guest does know best. The alternative is to give guests a shedload more MTRR ranges. This is kind of clunky and will also slow down the MTRR-range search which Xen currently does when working out guest effective memory type. But it does have the advantage of letting us have default type as UC, which I guess is the default type on just about every real machine in the world? -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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