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Re: [Xen-devel] Intel: Overly restrictive test for availablility of CPUI

To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Intel: Overly restrictive test for availablility of CPUID masking MSRs?
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Tue, 2 Mar 2010 15:35:59 +0000
Cc: Rob Hoes <Rob.Hoes@xxxxxxxxxx>, Jun Nakajima <jun.nakajima@xxxxxxxxx>, Liping Ke <liping.ke@xxxxxxxxx>
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On Tue, 2010-03-02 at 14:11 +0000, Ian Campbell wrote:

> > Is there a more precise way of detecting the presence of this
> > capability? I've seen:
> >         family > 0x6 || (model > 0x17 || (model = 0x17 && stepping >= 4))
> > suggested but this looks like it matches exactly the same set of
> > processors as the "eax < 0x00010674" in the code before aab9fbd6ffa0
> > which was apparently too lenient?

Or alternatively, is there any reason we can't just use wrmsr_safe
instead to gracefully handle processors which can't cope?


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