From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41226) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YMEGL-0003mm-Oo for qemu-devel@nongnu.org; Fri, 13 Feb 2015 06:18:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YMEGG-0006bh-OQ for qemu-devel@nongnu.org; Fri, 13 Feb 2015 06:18:21 -0500 Received: from cantor2.suse.de ([195.135.220.15]:37764 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YMEGG-0006bQ-Em for qemu-devel@nongnu.org; Fri, 13 Feb 2015 06:18:16 -0500 Message-ID: <54DDDD76.6060300@suse.de> Date: Fri, 13 Feb 2015 12:18:14 +0100 From: Alexander Graf MIME-Version: 1.0 References: <871tlu7p96.fsf@neno.neno> <54DD4701.7070908@suse.de> <20150213090456.GA2401@work-vm> In-Reply-To: <20150213090456.GA2401@work-vm> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] HEAD is failing virt-test on migration tests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: amit.shah@redhat.com, Developers qemu-devel , Lucas Meneghel Rodrigues , quintela@redhat.com On 13.02.15 10:04, Dr. David Alan Gilbert wrote: > * Alexander Graf (agraf@suse.de) wrote: >> >> >> On 13.02.15 01:29, Lucas Meneghel Rodrigues wrote: >>> Copying Alex. >>> >>> OK, after bisecting, this is what I've got: >>> >>> 8118f0950fc77cce7873002a5021172dd6e040b5 is the first bad commit >>> commit 8118f0950fc77cce7873002a5021172dd6e040b5 >>> Author: Alexander Graf > >>> Date: Thu Jan 22 15:01:39 2015 +0100 >>> >>> migration: Append JSON description of migration stream >>> >>> One of the annoyances of the current migration format is the fact that >>> it's not self-describing. In fact, it's not properly describing at all. >>> Some code randomly scattered throughout QEMU elaborates roughly how to >>> read and write a stream of bytes. >>> >>> We discussed an idea during KVM Forum 2013 to add a JSON description of >>> the migration protocol itself to the migration stream. This patch >>> adds a section after the VM_END migration end marker that contains >>> description data on what the device sections of the stream are >>> composed of. >>> >>> This approach is backwards compatible with any QEMU version reading the >>> stream, because QEMU just stops reading after the VM_END marker and >>> ignores >>> any data following it. >>> >>> With an additional external program this allows us to decipher the >>> contents of any migration stream and hopefully make migration bugs >>> easier >>> to track down. >>> >>> Signed-off-by: Alexander Graf > >>> Signed-off-by: Amit Shah >> > >>> Signed-off-by: Juan Quintela >> > >>> >>> :040000 040000 e9a8888ac242a61fbd05bbb0daa3e8877970e738 >>> 61df81f831bc86b29f65883523ea95abb36f1ec5 Mhw >>> :040000 040000 fe0659bed17d86c43657c26622d64fd44a1af037 >>> 7092a6b6515a3d0077f68ff2d80dbd74597a244f Minclude >>> :040000 040000 d90d6f1fe839abf21a45eaba5829d5a6a22abeb1 >>> c2b1dcda197d96657458d699c185e39ae45f3c6c Mmigration >>> :100644 100644 98895fee81edfbc659fc42d467e930d06b1afa7d >>> 80407662ad3ed860d33a9d35f5c44b1d19c4612b Msavevm.c >>> :040000 040000 cf218bc2b841cd51ebe3972635be2cfbb1de9dfa >>> 7aaf3d10ef7f73413b228e854fe6f04317151e46 Mtests >>> >>> So there you go. I'm going to sleep, if you need any extra help let me know. >> >> So the major difference with this patch applied is that the sender could >> send more data than the receive wants to read. I can't see the actual >> migrate command you used down there. >> >> I haven't seen this actually being a problem so far, as the receiver >> just close()s its file descriptor once it hits VM_EOF. This should only >> break senders if they expect they can send more. That said, I think I >> only tested offline migration (via exec:), so maybe QEMU is behaving >> badly and actually wants to send all data and just fails the migration >> without? > > Hmm, for such an odd change to the migration stream it's a surprise you > didn't test it live. Well, let's say I don't remember explicitly testing it live - I probably did at one point. I just verified that migrating with tcp:... works fine in master. Alex