From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: live migration between qemu-kvm 1.0 and 0.15 Date: Tue, 27 Mar 2012 17:59:08 +0200 Message-ID: <4F71E3CC.9070103@redhat.com> References: <20120327085521.GA4567@dhcp-192-168-178-175.profitbricks.localdomain> <4F718E8B.5090601@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Vasilis Liaskovitis , kvm@vger.kernel.org, qemu-devel@nongnu.org To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:54366 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750876Ab2C0P7Q (ORCPT ); Tue, 27 Mar 2012 11:59:16 -0400 In-Reply-To: <4F718E8B.5090601@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/27/2012 11:55 AM, Jan Kiszka wrote: > On 2012-03-27 10:55, Vasilis Liaskovitis wrote: > > Hi, > > > > is live migration between qemu-kvm stable-0.15 and stable-1.0 trees possible? > > When I live migrate a VM from 1.0 to 0.15, the destination side 0.15 qemu-kvm > > exits with: > > (qemu) Unknown savevm section or instance 'i8259' 0 > > > > That's expected, since commit "i8259:convert to qdev" 747c70af78f7088f182c87e683bdf847beead1e4 > > introduces the i8259 device in the qdev tree. > > > > The other direction (live migrate from 0.15.1 to 1.0.0) seems to work fine. > > Are any other issues expected in this direction? > > > > The vmstate for i8259 has not changed between these trees afaict. If the > > qdev-ified i8259 is reverted from stable-1.0 tree (to restore live-migration > > compatibility between the versions), would you expect problems? > > The legacy instance IDs used in old versions are not written out by > newer ones. They are just accepted on reading to allow moving forward. > There are more devices in the tree that used those instance IDs, not > only the i8259. Reverting the qdev conversion may reactivate backward > migratability for 1.0->0.15 (unless there are others as well). But that > will definitely be over after 1.1 as inrevertible code depends on the > qdev conversion. Is this true even for -M pc-0.15? -- error compiling committee.c: too many arguments to function