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Date: Thu, 18 Jun 2015 14:26:12 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
Message-ID: <20150618172612.GD3874@thinpad.lan.raisama.net>
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Subject: Re: [Qemu-devel] [PATCH 2/2] target-i386: automatically raise cpuid
	level to 0xd
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To: Bandan Das <bsd@redhat.com>
Cc: pbonzini@redhat.com, rth@twiddle.net, qemu-devel@nongnu.org, Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>

On Thu, Jun 18, 2015 at 01:12:32PM -0400, Bandan Das wrote:
> Eduardo Habkost <ehabkost@redhat.com> writes:
>=20
> > On Thu, Jun 18, 2015 at 05:24:24PM +0200, Radim Kr=C4=8Dm=C3=A1=C5=99=
 wrote:
> >> We already bump to level 7 if features there are requested, so do th=
e
> >> same for 0xD.
>=20
> But doesn't bumping to 7 for feat[ebx] have the potential to break
> ABI too ?

It's not the auto-bumping that breaks ABI, but having older
machine-types now exposing different CPUID data to guests after applying
the patch.

The auto-bump to 7 was introduced at the same time we introduced the
first CPUID[7] features, so you couldn't have any running machines that
would break.

--=20
Eduardo