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From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: eranian-sDzT885Ts8HQT0dZR+AlfA@public.gmane.org
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: CPUID emulation
Date: Thu, 31 May 2007 14:52:05 +0300	[thread overview]
Message-ID: <465EB6E5.7000000@qumranet.com> (raw)
In-Reply-To: <20070531114447.GF22798-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org>

Stephane Eranian wrote:
>>
>> If the guest cpuid is set to a least common denominator, it should work.
>>
>>     
> There is no common denominator between a P4 and Intel Core 2 Duo for the
> performance counters. So you cannot simply use a generic member of family
> 15 to fake the guest cpuid runnning on Intel Core 2 Duo host.
>
>   

So, the performance counter functionality will not be available if you 
have a mixed server farm with these processors.

If applications use model version to detect performance counters, and 
not cpuid bits, then there is no way to prevent guests using performance 
counters.  Fortunately this is limited to specialized applications.

-- 
error compiling committee.c: too many arguments to function


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  parent reply	other threads:[~2007-05-31 11:52 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-31  8:20 CPUID emulation Stephane Eranian
     [not found] ` <20070531082006.GB22798-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org>
2007-05-31  8:39   ` Avi Kivity
     [not found]     ` <465E89A8.9020201-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-05-31 11:29       ` Stephane Eranian
     [not found]         ` <20070531112906.GC22798-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org>
2007-05-31 11:35           ` Avi Kivity
     [not found]             ` <465EB310.7080402-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-05-31 11:44               ` Stephane Eranian
     [not found]                 ` <20070531114447.GF22798-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org>
2007-05-31 11:52                   ` Avi Kivity [this message]
     [not found]                     ` <465EB6E5.7000000-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-05-31 11:58                       ` Stephane Eranian
     [not found]                         ` <20070531115841.GG22798-HU54gidqsKnWxDs0y9d3MAC/G2K4zDHf@public.gmane.org>
2007-05-31 15:12                           ` Troy Benjegerdes
     [not found]                             ` <20070531151244.GC6474-na1kE3HDu0idQnJuSAr7PQ@public.gmane.org>
2007-05-31 15:38                               ` ron minnich
2007-05-31 18:30                           ` Ulrich Drepper
     [not found]                             ` <465F145F.5040003-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2007-06-01  1:12                               ` H. Peter Anvin

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