From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43192) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYG5A-0000KY-TP for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:36:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WYG53-0002aA-GL for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:36:00 -0400 Received: from mail-pd0-f177.google.com ([209.85.192.177]:36732) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYG53-0002a2-BQ for qemu-devel@nongnu.org; Thu, 10 Apr 2014 10:35:53 -0400 Received: by mail-pd0-f177.google.com with SMTP id y10so3898554pdj.8 for ; Thu, 10 Apr 2014 07:35:52 -0700 (PDT) Message-ID: <5346AC43.2060600@ozlabs.ru> Date: Fri, 11 Apr 2014 00:35:47 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1395888071-28677-1-git-send-email-aik@ozlabs.ru> <53341B8F.7040904@suse.de> <53341E41.7050101@ozlabs.ru> <533422AB.7080106@ozlabs.ru> <53435036.9020901@ozlabs.ru> <53468A29.50404@suse.de> In-Reply-To: <53468A29.50404@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH] target-ppc: Add @cpu_dt_id into migration stream List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf , Peter Maydell Cc: "qemu-ppc@nongnu.org" , =?UTF-8?B?QW5kcmVhcyBGw6Q=?= =?UTF-8?B?cmJlcg==?= , QEMU Developers On 04/10/2014 10:10 PM, Alexander Graf wrote: > > On 08.04.14 03:26, Alexey Kardashevskiy wrote: >> On 03/28/2014 12:07 AM, Alexey Kardashevskiy wrote: >>> On 03/27/2014 11:57 PM, Peter Maydell wrote: >>>> On 27 March 2014 12:49, Alexey Kardashevskiy wrote: >>>>> On 03/27/2014 11:37 PM, Andreas Färber wrote: >>>>>> Am 27.03.2014 03:41, schrieb Alexey Kardashevskiy: >>>>>>> This should prevent the destination guest from misbehaving when >>>>>>> the threads number is different in "-smp" command. >>>>>> Sorry, I don't understand. When migrating, surely -smp needs to be the >>>>>> same on source and destination, so how can they differ? >>>>> >>>>> The idea is that "-smp" does not migrate and if we run source and >>>>> destination guests with different numbers in -smp, we end up with weird >>>>> machine >>>> Yes, so don't do that. As I understand it: >>>> (1) if you don't run QEMU with the exact same command line >>>> and config at both ends then migration won't work >>>> (2) we don't guarantee to detect and cleanly fail if you >>>> don't do (1) >>>> >>>> It would probably be nice if we did detect config mismatches, >>> Yep, we do not send the device tree (as libvirt does). Pure command line >>> matching won't work. >>> >>>> but that seems to me like a problem we should be addressing >>>> more globally than just for one particular config item for >>>> one particular target... >> >> Ok. So. Let's assume I want to implement migration of "-smp" parameters. >> What would be the correct way of doing this in terms of the current QOM >> principles? Thanks. > > You don't. The migration protocol doesn't migrate configuration. If you > want to start to transfer VM configuration (which I'd be all in for), do it > properly and transfer _all_ configuration. Then what is the purpose of many, many VMSTATE_.*_EQUAL? And I do not want to send configuration by the proposed patch, I want to make sure that the new guest is able to continue. Why exactly is this bad? -- Alexey