From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:34845)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1Qf9nw-00071m-8C
	for qemu-devel@nongnu.org; Fri, 08 Jul 2011 08:05:13 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1Qf9nu-0002QI-Ej
	for qemu-devel@nongnu.org; Fri, 08 Jul 2011 08:05:08 -0400
Received: from mx1.redhat.com ([209.132.183.28]:12544)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1Qf9nu-0002Pz-1u
	for qemu-devel@nongnu.org; Fri, 08 Jul 2011 08:05:06 -0400
Received: from int-mx01.intmail.prod.int.phx2.redhat.com
	(int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11])
	by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p68C55el004428
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK)
	for <qemu-devel@nongnu.org>; Fri, 8 Jul 2011 08:05:05 -0400
Message-ID: <4E16F26D.40404@redhat.com>
Date: Fri, 08 Jul 2011 14:05:01 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1310115239-19288-1-git-send-email-kraxel@redhat.com>
	<4E16D3D8.60908@redhat.com> <4E16D4EF.5020903@redhat.com>
	<4E16D949.2060305@redhat.com> <4E16EE6A.6000506@redhat.com>
In-Reply-To: <4E16EE6A.6000506@redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 0/3] non-migratable devices
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org

On 07/08/2011 01:47 PM, Gerd Hoffmann wrote:
>
>
>> scsi-cd is new in 0.15, older versions have scsi-disk only. That's why
>> we should take the occasion to add the empty vmstate at least to it.
>
> Ok, good opportunity in that specific case.
>
>> For other devices, it's better to make the breakage in a single version.
>> It also allows to make 0.15 the "flag day" where each device shall have
>> a VMState or the entire VM will not be migratable.
>
> Not that easy given that we didn't fully migrate to vmstate yet,
> otherwise we could simply fail migration in case we find any device with
> qdev->vmsd == NULL.

You can always add

#define VMSD_NONE  ((const VMStateDescription *) 1)

>> If desired, in the
>> future we can revert this behavior for pc-0.14 and earlier machines.
>
> And I'm still looking for a sane way to handle *this*.

One possibility is to add device name remapping to machine types, like 
"ide is actually ide-0.14 when using pc-0.14" and put a different 
VMState in ide-0.14.

Paolo