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SubjectRe: [RFC] CPUID usage for interaction between Hypervisors and Linux.
Jeremy Fitzhardinge wrote:
> Alok Kataria wrote:
>
> I guess, but the bulk of the uses of this stuff are going to be
> hypervisor-specific. You're hard-pressed to come up with any other
> generic uses beyond tsc.

And arguably, storing TSC frequency in CPUID is a terrible interface
because the TSC frequency can change any time a guest is entered. It
really should be a shared memory area so that a guest doesn't have to
vmexit to read it (like it is with the Xen/KVM paravirt clock).

Regards,

Anthony Liguori

> In general, if a hypervisor is going to put something in a special
> cpuid leaf, its because there's no other good way to represent it.
> Generic things are generally going to appear as an emulated piece of
> the virtualized platform, in ACPI, DMI, a hardware-defined cpuid leaf,
> etc...



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