Re: [RFC] x86: xsave/xrstor support, ucontext_t extensions

[H. Peter Anvin]

Roland McGrath wrote:
> > hmm.. so the kernel needs to export all the cpuid info (that the kernel
> > enables and supports) to the user through some mechanism then?
>
> For a cheap interface, we use AT_HWCAP for this.  Unfortunately that only
> covers the first 32 bits of CPUID info.  (For another cheap interface,
> giving all the CPUID bits in the vDSO would be easy.)
>
> For a clunky interface that already exists and is "simple" to use,
> there is /dev/cpu/0/cpuid now.  I wonder if having a device node and
> opening it too much for applications that consider the vDSO too complex.

I doubt it.

	-hpa

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