From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59496) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7AHl-0004v0-UV for qemu-devel@nongnu.org; Mon, 12 Mar 2012 14:47:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S7AHg-0007RL-T9 for qemu-devel@nongnu.org; Mon, 12 Mar 2012 14:47:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63030) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7AHg-0007Qv-KP for qemu-devel@nongnu.org; Mon, 12 Mar 2012 14:47:52 -0400 Message-ID: <4F5E445A.7000201@redhat.com> Date: Mon, 12 Mar 2012 20:45:46 +0200 From: Yonit Halperin MIME-Version: 1.0 References: <4F5CA590.1000605@redhat.com> <4F5CB429.4000907@codemonkey.ws> <20120311152528.GD7273@garlic.redhat.com> <4F5CC692.7050002@codemonkey.ws> <4F5DAC69.6010002@redhat.com> <4F5DB906.2030508@redhat.com> <4F5DC604.9010702@redhat.com> <4F5DF074.2030305@redhat.com> <4F5DFF3B.3040007@redhat.com> In-Reply-To: <4F5DFF3B.3040007@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Spice-devel] seamless migration with spice List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Anthony Liguori , Hans de Goede , Alon Levy , qemu-devel , "spice-devel@freedesktop.org" Hi, On 03/12/2012 03:50 PM, Gerd Hoffmann wrote: > Hi, > >> Can you explain/exemplify, why sending data as a blob (either by (a) or >> (b)), that is verified only by the two ends that actually use it, is a >> problem? > > It tends to be not very robust. Especially when the creating/parsing is > done ad-hoc and the format changes now and then due to more info needing > to be stored later on. The qemu migration format which has almost no > structure breaks now and then because of that. Thus I'd prefer to not > go down this route when creating something new. > > cheers, > Gerd Exposing spice server internals to the client/qemu seems to me more vulnerable then sending it as a blob. Nonetheless, it introduces more complexity to backward compatibility support and it will need to involve not only the capabilities/versions of the server but also those of the qemu/client. Which reminds me, that we also need capabilities negotiation for the migration protocol between the src and the destination. Regards, Yonit.