Re: Standardizing an MSR or other hypercall to get an RNG seed?

Nakajima, Jun
2014-09-19T00:49:45Z

On Thu, Sep 18, 2014 at 3:07 PM, Andy Lutomirski <luto@amacapital.net> wrote:

> So, as a concrete straw-man:
>
> CPUID leaf 0x48000000 would return a maximum leaf number in EAX (e.g.
> 0x48000001) along with a signature value (e.g. "CrossHVPara\0") in
> EBX, ECX, and EDX.
>
> CPUID 0x48000001.EAX would contain an MSR number to read to get a
> random number if supported and zero if not supported.
>
> Questions:
>
> 1. Can we use a fixed MSR number? This would be a little bit simpler,
> but it would depend on getting a wider MSR range from Intel.
>

Why do you need a wider MSR range if you always detect the feature by
CPUID.0x48000001?
Or are you still trying to avoid the detection by CPUID?

--
Jun
Intel Open Source Technology Center