Re: [Xen-devel] [PATCH 10/24] xen: mask XSAVE from cpuid

[Andi Kleen]

> The point is YOU DON'T KNOW.  In particular, there might be new traps,
> there might be new state, there might be new MSRs, there might be new
> control bits... anything.  Therefore, you cannot blindly pass the bit
> on, even though XSAVE solves one part of the problem.

I think what will happen if you don't expose it is that there will
be always hypervisors which are behind and applications/OS will end up
doing probing for opcodes instead of trusting CPUID bits.

Probably not what you intended.

-Andi
-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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