From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=54731 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OGu2p-0000za-I2 for qemu-devel@nongnu.org; Tue, 25 May 2010 09:19:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OGu2o-0006TA-CK for qemu-devel@nongnu.org; Tue, 25 May 2010 09:19:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3877) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OGu2o-0006Sz-4S for qemu-devel@nongnu.org; Tue, 25 May 2010 09:19:42 -0400 Message-ID: <4BFBCE6A.1000201@redhat.com> Date: Tue, 25 May 2010 16:19:38 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH v2 12/15] monitor: Add basic device state visualization References: <1f557b9feb1965a61e64f7166bcf4918bed8d0ec.1274516288.git.jan.kiszka@web.de> <4BF82895.6000706@redhat.com> <4BFAE004.6090501@codemonkey.ws> <4BFB7B06.2090005@redhat.com> <4BFBCABC.5040707@linux.vnet.ibm.com> In-Reply-To: <4BFBCABC.5040707@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Juan Quintela , Jan Kiszka , qemu-devel@nongnu.org, Luiz Capitulino , Jan Kiszka , Markus Armbruster On 05/25/2010 04:03 PM, Anthony Liguori wrote: >> >>> I don't think that qdev device names and paths are something we have >>> to worry much about changing over time since they reflect logical >>> bus layout. They should remain static provided the devices remain >>> static. >> >> Modulo mistakes. We already saw one (lack of pci domains). To >> reduce the possibility of mistakes, we need reviewable documentation. > > > pci domains was only a mistake as a nice-to-have. We can add pci > domains in a backwards compatible way. It adds a new level to the qdev tree. Of course we can hide the new level for older clients, and newer clients can drop the level for older qemus, but it will be oh-so-painful. > > The arguments you're making about the importance of backwards > compatibility and what's needed to strongly guarantee it are equally > applicable to the live migration protocol. We really do need to > formally document the live migration protocol in such a way that it's > reviewable if we hope to truly make it compatible across versions. Mostly agreed. I think live migration has a faster/easier deprecation schedule (easier not to support migration from 0.n-k to 0.n than to remove qmp support for a feature introduced in 0.n-k when releasing 0.n). But that's a minor concern, improving our externally visible interface documentation is a good thing and badly needed. -- error compiling committee.c: too many arguments to function