Message-ID: <48E41C94.7040904@kernel.org>
Date: Wed, 01 Oct 2008 17:57:56 -0700
From: "H. Peter Anvin" <hpa@kernel.org>
Organization: Linux Kernel Organization, Inc.
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To: Zachary Amsden <zach@vmware.com>
CC: Anthony Liguori <anthony@codemonkey.ws>,
       Jeremy Fitzhardinge <jeremy@goop.org>,
       Alok Kataria <akataria@vmware.com>, "avi@redhat.com" <avi@redhat.com>,
       Rusty Russell <rusty@rustcorp.com.au>,
       Gerd Hoffmann <kraxel@redhat.com>, Ingo Molnar <mingo@elte.hu>,
       the arch/x86 maintainers <x86@kernel.org>,
       LKML <linux-kernel@vger.kernel.org>,
       "Nakajima, Jun" <jun.nakajima@intel.com>,
       Daniel Hecht <dhecht@vmware.com>,
       "virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
       "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC] CPUID usage for interaction between Hypervisors	and	Linux.
References: <1222881242.9381.17.camel@alok-dev1> <48E3BBC1.2050607@goop.org>	 <1222894878.9381.63.camel@alok-dev1> <48E3E8DE.1080602@goop.org>	 <48E3ECD1.30809@codemonkey.ws> <1222904824.7330.83.camel@bodhitayantram.eng.vmware.com> <48E4183A.7090208@zytor.com>
In-Reply-To: <48E4183A.7090208@zytor.com>
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H. Peter Anvin wrote:
> 
> Ah, if it was only that simple.  Transmeta actually did this, but it's 
> not as useful as you think.
> 

For what it's worth, Transmeta's implementation used CPUID leaf 
0x80860001.ECX to give the TSC frequency rounded to the nearest MHz. 
The caveat of spread-spectrum modulation applies.

	-hpa
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