From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: Standardizing an MSR or other hypercall to get an RNG seed?
Date: Fri, 19 Sep 2014 08:04:44 +0200
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To: David Hepkin <davidhep@microsoft.com>, Andy Lutomirski <luto@amacapital.net>, Niels Ferguson <niels@microsoft.com>
Cc: Mathew John <mathewj@microsoft.com>, Theodore Ts'o <tytso@mit.edu>, John Starks <John.Starks@microsoft.com>, kvm list <kvm@vger.kernel.org>, Gleb Natapov <gleb@kernel.org>, Linux Virtualization <virtualization@lists.linux-foundation.org>, "H. Peter Anvin" <hpa@zytor.com>, Jake Oshins <jakeo@microsoft.com>
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Il 18/09/2014 23:54, David Hepkin ha scritto:
> The chief advantage I see to using a hypercall based mechanism is
> that it would work across more architectures.  MSR's and CPUID's are
> specific to X86.  If we ever wanted this same mechanism to be
> available on an architecture that doesn't support MSR's,  a hypercall
> based approach would allow for a more consistent mechanism across the
> architectures.
> 
> I agree, though, that converging on a common hypercall interface that
> would be implemented by all of the hypervisors would likely be much
> harder to achieve.

There are differences between architectures at the hypercall level,
starting with the calling convention.  So I don't think it makes much
sense to use a hypercall.

Paolo