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    SubjectRe: [RFC PATCH 18/33] Subarch support for CPUID instruction
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    On Tue, 2006-07-18 at 00:00 -0700, Chris Wright wrote:
    > plain text document attachment (i386-cpuid)
    > Allow subarchitectures to modify the CPUID instruction. This allows
    > the subarch to provide a limited set of CPUID feature flags during CPU
    > identification. Add a subarch implementation for Xen that traps to the
    > hypervisor where unsupported feature flags can be hidden from guests.

    Hi,

    I'm wondering if this is entirely the wrong level of abstraction; to me
    it feels the subarch shouldn't override the actual cpuid, but the cpu
    feature flags that linux uses. That's a lot less messy: cpuid has many
    many pieces of information which are near impossible to filter in
    practice, however filtering the USAGE of it is trivial; linux basically
    flattens the cpuid namespace into a simple bitmap of "what the kernel
    can use". That is really what the subarch should filter/fixup, just like
    we do for cpu quirks etc etc.

    Greetings,
    Arjan van de Ven

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