From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1NDEHT-0002HI-41
	for qemu-devel@nongnu.org; Wed, 25 Nov 2009 04:35:23 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1NDEHO-0002Ey-DU
	for qemu-devel@nongnu.org; Wed, 25 Nov 2009 04:35:22 -0500
Received: from [199.232.76.173] (port=59575 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1NDEHO-0002Er-0M
	for qemu-devel@nongnu.org; Wed, 25 Nov 2009 04:35:18 -0500
Received: from mx1.redhat.com ([209.132.183.28]:55450)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <mst@redhat.com>) id 1NDEHN-0005ua-Je
	for qemu-devel@nongnu.org; Wed, 25 Nov 2009 04:35:17 -0500
Received: from int-mx03.intmail.prod.int.phx2.redhat.com
	(int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16])
	by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id nAP9ZGQl024833
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK)
	for <qemu-devel@nongnu.org>; Wed, 25 Nov 2009 04:35:16 -0500
Date: Wed, 25 Nov 2009 11:32:37 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20091125093237.GA7285@redhat.com>
References: <4B0952C9.9010803@redhat.com> <m3my2d4euy.fsf@neno.neno>
	<4B0BB7F6.5090103@redhat.com>
	<20091124140144.GK2405@redhat.com> <m3r5rot34h.fsf@neno.neno>
	<20091124160500.GD6737@redhat.com> <m33a43rlx4.fsf@neno.neno>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <m33a43rlx4.fsf@neno.neno>
Subject: [Qemu-devel] Re: Live migration protocol, device features,
	ABIs and other beasts
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Juan Quintela <quintela@redhat.com>
Cc: Dor Laor <dlaor@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On Wed, Nov 25, 2009 at 10:30:47AM +0100, Juan Quintela wrote:
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > On Tue, Nov 24, 2009 at 03:21:34PM +0100, Juan Quintela wrote:
> 
> > A device already supports load for a range
> > of versions between X and Y. We want to support
> > saving to a range of versions.
> >
> > Which versions to use is a separate decision
> > which should be taken on run time, not
> > at startup time.
> 
> Not in the general case.

If that means "not in all cases", I agree.
But it seems pretty common for bugfixes.

> Think that v8 brings featureX to one device.  If you _know_ that you don't
> want to use feature X, startup time is the proper place.  Important
> thing is not the savevm format (we can do any change here), what we
> really need is that the guest still runs on the destination, and for
> that you can't change the hardware too much.
> 
> Later, Juan.

I think it's clear: if you change guest visible properties
these are features that might belong in machine description.
If not - they don't belong in machine description.

-- 
MST