From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56076) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anca4-0001In-Gw for qemu-devel@nongnu.org; Tue, 05 Apr 2016 21:48:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1anca1-0007r6-9j for qemu-devel@nongnu.org; Tue, 05 Apr 2016 21:48:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55618) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anca1-0007qR-3k for qemu-devel@nongnu.org; Tue, 05 Apr 2016 21:48:25 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3B308C049D5D for ; Wed, 6 Apr 2016 01:48:24 +0000 (UTC) References: <1483e0d74dcfd183ff46dd63cc57e1fe8b775bf8.1454680535.git.amit.shah@redhat.com> <56BC86C6.6060103@redhat.com> <20160222123940.GD10967@grmbl.mre> <56CC0422.3010005@redhat.com> <20160223074121.GF10967@grmbl.mre> <20160405133233.GF2242@work-vm> From: Jason Wang Message-ID: <57046AE3.8000105@redhat.com> Date: Wed, 6 Apr 2016 09:48:19 +0800 MIME-Version: 1.0 In-Reply-To: <20160405133233.GF2242@work-vm> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PULL 8/9] static checker: e1000-82540em got aliased to e1000 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , Amit Shah Cc: Paolo Bonzini , qemu list , Juan Quintela On 04/05/2016 09:32 PM, Dr. David Alan Gilbert wrote: > * Amit Shah (amit.shah@redhat.com) wrote: >> On (Tue) 23 Feb 2016 [15:02:58], Jason Wang wrote: >>>>> This means that 2.5 cannot migrate 2.4 virtual machines, right? Is that >>>>> something we want to rectify in 2.6 by making e1000-82540em an alias of >>>>> e1000 (instead of the other way round)? >>>> You're right; I misread it. With that commit (8304402033): >>>> >>>> 2.4 with e1000-82540em will not migrate to 2.5 with e1000-82540em. >>>> >>>> This is despite they're aliased (so the cmdline is backward >>>> compatible), but the migration device name actually changed. >>>> >>>> Of course, 2.5->2.4 will also not work. >>>> >>>> Since 2.4 emits 'e1000-82540em' as the device name in the migration >>>> stream, and 2.5 emits just 'e1000', we have two different names for >>>> the same device in two versions. >>>> >>>> To fix this, we'll need a hack on the dest side to allow e1000 and >>>> e1000-82540em in the migration stream for the device, and this can be >>>> done for 2.6 and 2.5.stable. >>>> >>>> Jason, can you attempt this? >>>> >>> Sure, but just need to understand the "problem". If I understand this >>> correctly, the issue only happen for JSON description at the end of >>> migration stream, and it won't break migration in fact? >> No, this does break migration. >> >> The stream contained 'e1000-82540em' as the section header for the >> device earlier. It now only has 'e1000'. So a newer qemu will only >> accept 'e1000', but not 'e1000-82540em' (from an older release). > OK, so do we need to get this fixed for 2.6 - i.e. now. > > Dave Sorry for the late response. Have a try with 2.4 -> 2.5 migration and it works. Looking at save_section_header(), it will save se->idstr which seems always be "e1000" even if e1000-82540em is used in cli, or is there anything I missed? > >> Amit > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK