From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=41122 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OGuUR-0006Mw-Ip for qemu-devel@nongnu.org; Tue, 25 May 2010 09:48:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OGuDy-0008Jt-0e for qemu-devel@nongnu.org; Tue, 25 May 2010 09:31:22 -0400 Received: from mail-qy0-f198.google.com ([209.85.221.198]:64907) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OGuDx-0008Jn-TW for qemu-devel@nongnu.org; Tue, 25 May 2010 09:31:13 -0400 Received: by qyk36 with SMTP id 36so6941389qyk.19 for ; Tue, 25 May 2010 06:31:13 -0700 (PDT) Message-ID: <4BFBD11E.7030609@codemonkey.ws> Date: Tue, 25 May 2010 08:31:10 -0500 From: Anthony Liguori 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> <4BFBCE6A.1000201@redhat.com> In-Reply-To: <4BFBCE6A.1000201@redhat.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: Avi Kivity Cc: Juan Quintela , Jan Kiszka , qemu-devel@nongnu.org, Luiz Capitulino , Anthony Liguori , Jan Kiszka , Markus Armbruster On 05/25/2010 08:19 AM, Avi Kivity wrote: > 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. The tree is not organized like that today. IOW, the PCI hierarchy is not reflected in the qdev hierarchy. All PCI devices (regardless of whether they're a function or a full slot) simply sit below the PCI bus. >> >> 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. > Regards, Anthony Liguori