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    SubjectRe: [GIT PULL] xen /proc/mtrr implementation
    Ingo Molnar wrote:
    >> That's it. I could add any number of bizarre convolutions to
    >> achieve the same effect, but given that there's an existing
    >> interface that is exactly designed for what we want to achieve, I
    >> have to admit it didn't occur to me to do anything else.
    > Exactly what is 'bizarre' about using the API defined by the _CPU_
    > already, without adding any ad-hoc hypecall? Catch the dom0 WRMSRs,
    > filter out the MTRR indices - that's it.

    Well, the x86 world can't seem to decide what the ABI is supposed to be,
    which is why we have mtrr_ops in the first place. Doing emulation at
    the MSR level means that I'd need to decide which MTRR interface we're
    emulating today and do that.

    Yes, I realize that almost everyone is using the same Intel-like
    interface these days, but it does mean there's a level of fragility that
    doesn't exist if we just implement mtrr_ops.

    There's some secondary issues which arise. For example, the mtrr
    trimming test is meaningless in dom0 (the e820 is fake, so it doesn't
    make sense to compare it with the mtrrs); we currently avoid that
    because the test only happens if the mtrr vendor is Intel. We would
    need to disable that test some other way.


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      Last update: 2009-05-20 18:15    [W:0.019 / U:6.988 seconds]
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