From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andi Kleen <andi@firstfloor.org>
Subject: Re: Cross vendor migration ideas
Date: Sat, 15 Nov 2008 14:03:46 +0100
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Cc: "Skywing" <Skywing@valhallalegends.com>,
	"Alexander Graf" <agraf@suse.de>,
	"Anthony Liguori" <anthony@codemonkey.ws>, <kvm@vger.kernel.org>,
	"Amit Shah" <amit.shah@redhat.com>, "Avi Kivity" <avi@redhat.com>,
	"Wahlig, Elsie" <elsie.wahlig@amd.com>,
	"Nakajima, Jun" <jun.nakajima@intel.com>
To: "Serebrin, Benjamin (Calendar)" <Benjamin.Serebrin@exchange.amd.com>
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In-Reply-To: <7CCF7468C07AFF4B991DD1528058EC2F042C7283@SSVLEXMB1.amd.com> (Benjamin Serebrin's message of "Wed, 12 Nov 2008 17:48:21 -0800")
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"Serebrin, Benjamin (Calendar)" <Benjamin.Serebrin@exchange.amd.com> writes:
>
> 64-bit OSes will use SYSCALL for 64-bit code.  CPUID name string should
> be "FakeCPUFakeCPU"

One problem is that you'll disable a lot of vendor specific setup 
code if you do that. Might have all kinds of unexpected side effects.

Also it might break user space, unless you key the fake vendor CPUID
intercept on ring 0 vs ring 3 (but even if that might not be enough
because some kernel modules can call CPUID on their own)

I think just emulating SYSCALL/SYSENTER would be safer. It shouldn't
be that much slower than int 0x80 hopefully.

-Andi