From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [RFC] CPUID usage for interaction between Hypervisors and Linux.
Date: Wed, 01 Oct 2008 13:08:08 -0700
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Cc: akataria@vmware.com, kvm@vger.kernel.org,
	the arch/x86 maintainers <x86@kernel.org>,
	Dan Hecht <dhecht@vmware.com>,
	LKML <linux-kernel@vger.kernel.org>,
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	"avi@redhat.com" <avi@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>
To: Anthony Liguori <anthony@codemonkey.ws>
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Anthony Liguori wrote:
> Mmm, cpuid bikeshedding :-)

My shade of blue is better.

>> The space 0x40000000-0x400000ff is reserved for hypervisor usage.
>>
>> This region is divided into 16 16-leaf blocks.  Each block has the 
>> structure:
>>
>> 0x400000x0:
>>     eax: max used leaf within the leaf block (max 0x400000xf)
>
> Why even bother with this?  It doesn't seem necessary in your proposal.

It allows someone to incrementally add things to their block in a fairly 
orderly way.  But more importantly, its the prevailing idiom, and the 
existing and proposed cpuid schemes already do this, so they'd fit in as-is.

    J