From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42759) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1annt4-0001w0-BE for qemu-devel@nongnu.org; Wed, 06 Apr 2016 09:52:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1annt0-0007TH-8c for qemu-devel@nongnu.org; Wed, 06 Apr 2016 09:52:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37559) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1annt0-0007T5-2e for qemu-devel@nongnu.org; Wed, 06 Apr 2016 09:52:46 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (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 0E7A7ED25F for ; Wed, 6 Apr 2016 13:52:45 +0000 (UTC) Date: Wed, 6 Apr 2016 19:22:26 +0530 From: Amit Shah Message-ID: <20160406135226.GC21483@grmbl.mre> 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> <57046AE3.8000105@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57046AE3.8000105@redhat.com> 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: Jason Wang Cc: Paolo Bonzini , Juan Quintela , "Dr. David Alan Gilbert" , qemu list On (Wed) 06 Apr 2016 [09:48:19], Jason Wang wrote: > > > 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? OK, sorry for the wrong alarm. The VMStateDescription's 'name' field has remained the same; but the section name has changed, which is fine (that isn't transmitted over the wire). So my initial reading was correct - and the whitelist I added in 1483e0d74dcfd183ff46dd63cc57e1fe8b775bf8 is fine. So nothing needed for the migration stream. Thanks, Jason. Amit