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SubjectRe: [GIT PULL][RESEND #2] KVM Updates for 2.6.23-rc1
Linus Torvalds wrote:
>
> Actually, I think the *real* solution would be:
>
> - add a X86_HAS_CMPXCHG8B config option, and set it for the appropriate
> CPU selection (P6 and up, or whatever the rule is)
>
> - make KVM depend on it
>
> - make KVM and HIGHMEM64 _select_ another config option, namely the
> NEEDS_CMPXCHG8B
>
> and then we make the cpufeatures code check the CMPXCHG bit only if the
> NEEDS_CMPXCHG8B thing is set. That gives us the best of all worlds.
>
> Because there is no point in checking whether the CPU supports it if the
> kernel doesn't _need_ it. Especially since we know that some CPU's lie
> about it due to old NT bugs.
>

Yes. This is probably also true for other CPU feature options, at least
in the abstract (i.e. it may not apply to any of the current options).

-hpa
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