From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1Mntey-0005iX-TH
	for qemu-devel@nongnu.org; Wed, 16 Sep 2009 08:30:56 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1Mntet-0005fB-V3
	for qemu-devel@nongnu.org; Wed, 16 Sep 2009 08:30:56 -0400
Received: from [199.232.76.173] (port=47937 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Mntet-0005es-N9
	for qemu-devel@nongnu.org; Wed, 16 Sep 2009 08:30:51 -0400
Received: from mx20.gnu.org ([199.232.41.8]:42838)
	by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32)
	(Exim 4.60) (envelope-from <mst@redhat.com>) id 1Mntet-0007R0-6H
	for qemu-devel@nongnu.org; Wed, 16 Sep 2009 08:30:51 -0400
Received: from mx1.redhat.com ([209.132.183.28])
	by mx20.gnu.org with esmtp (Exim 4.60)
	(envelope-from <mst@redhat.com>) id 1Mnter-0003KS-Vh
	for qemu-devel@nongnu.org; Wed, 16 Sep 2009 08:30:50 -0400
Received: from int-mx05.intmail.prod.int.phx2.redhat.com
	(int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18])
	by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n8GCUmPM022002
	for <qemu-devel@nongnu.org>; Wed, 16 Sep 2009 08:30:48 -0400
Date: Wed, 16 Sep 2009 15:29:01 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20090916122901.GA4729@redhat.com>
References: <20090916104620.GA4456@redhat.com> <m34or3up58.fsf@neno.mitica>
	<20090916114133.GA4567@redhat.com> <m3k4zzt7e5.fsf@neno.mitica>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <m3k4zzt7e5.fsf@neno.mitica>
Subject: [Qemu-devel] Re: optional feature
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: qemu-devel@nongnu.org, gleb@redhat.com

On Wed, Sep 16, 2009 at 02:13:06PM +0200, Juan Quintela wrote:
> VMState rules are simple:
> - Everything is explicit

By the way, pci currently has cmask,
which performs checking on load, making sure
that load does not modify a constant field in config space,
which can't change as a result of guest actions.
If it does - migration fails.

This is IMO much better and more robust than
simply hoping that there are no bugs or that
developers remember to increment a version
number each time they change some field.

I think it's pretty important to keep this
feature, and maybe add something similar
to other devices.

How will VMState support this?

-- 
MST