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Re: [Xen-devel] [PATCH 2/2] hvm: allow pass-through of new CPUID feature

To: Andre Przywara <andre.przywara@xxxxxxx>
Subject: Re: [Xen-devel] [PATCH 2/2] hvm: allow pass-through of new CPUID features
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Thu, 27 Jan 2011 12:13:03 +0000
Cc: Keir Fraser <keir@xxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
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On Thu, 27 Jan 2011, Andre Przywara wrote:
> Ian Jackson wrote:
> > Andre Przywara writes ("[Xen-devel] [PATCH 2/2] hvm: allow pass-through of 
> > new CPUID features"):
> >> there are some new CPUID features that are safe for guests to see, as 
> >> they don't require OS awareness (FPU/ALU related instructions only). 
> >> Among features for new AMD CPUs there is also the PCLMULQDQ bit, which 
> >> Intel CPU have already for quite a while.
> > 
> > This would seem to be a new feature.
> I agree to some point, although (at least in respect to PCLMULQDQ) I'd 
> consider this more as "forgotten enablement".
>  > We are currently in feature freeze.
> > 
> > Can you make a justification for a freeze exception ?
> If you can make me believe that it does not take another year until this 
> shows up in an official release, then I am totally fine with skipping 4.1.0.
> What is the policy regarding the 4.1.x releases? Have features like 
> those a chance of being applied?

I think Ian was just looking for a well written explanation of why we
need this now :)

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