From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55934) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOD57-0007HU-PL for qemu-devel@nongnu.org; Tue, 16 Oct 2012 15:45:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TOD56-0004eC-G3 for qemu-devel@nongnu.org; Tue, 16 Oct 2012 15:45:37 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:59702) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOD56-0004e5-C6 for qemu-devel@nongnu.org; Tue, 16 Oct 2012 15:45:36 -0400 Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 16 Oct 2012 15:45:35 -0400 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 71A266E8071 for ; Tue, 16 Oct 2012 15:45:20 -0400 (EDT) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q9GJjKgh305234 for ; Tue, 16 Oct 2012 15:45:20 -0400 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q9GJjKCX007280 for ; Tue, 16 Oct 2012 16:45:20 -0300 Message-ID: <507DB94E.7040400@linux.vnet.ibm.com> Date: Tue, 16 Oct 2012 15:45:18 -0400 From: Corey Bryant MIME-Version: 1.0 References: <1350409868-2117-1-git-send-email-coreyb@linux.vnet.ibm.com> <507DB4F2.3090309@redhat.com> In-Reply-To: <507DB4F2.3090309@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 0/4] command line fd passing using fd sets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , Stefan Hajnoczi Cc: kwolf@redhat.com, libvir-list@redhat.com, qemu-devel@nongnu.org On 10/16/2012 03:26 PM, Eric Blake wrote: > On 10/16/2012 11:51 AM, Corey Bryant wrote: >> This series adds command line file descriptor passing support >> via a new -add-fd option. This is a follow-on to the existing >> QMP fd passing support provided in the following patch series: >> comments.gmane.org/gmane.comp.emulators.qemu/165463 >> >> The new -add-fd option is designed to mirror the add-fd QMP >> option as much as possible. > > Before this can still be useful in libvirt, we need a way to pass in fds > for all of a backing chain, and not just the top-level. And you can't > argue that libvirt should be temporarily rewriting qcow2 metadata to > stick in names such as /dev/fdset/1 into the metadata. Consider the > case of: > > /- guest1.img > base.img <- snap1.img < > \- guest2.img > > snap1.img is supposed to be read-only, and there's no guarantee that > /dev/fdset/1 will be available for both guest1 and guest2 to rewrite the > header. Thus, I argue that snap1.img must encode the name base.img in > its metadata, but that we must also have a way to tell qemu to open > /dev/fdset/1 instead of trying open(base.img) in order to get the open > fd for base.img. I think the -blockdev command is going to solve this. Stefan, do you have any information on the -blockdev support? > > But even though we are still not at a point where the overall feature is > useful, I can at least review these patches for getting us incrementally > closer to our goal. > Thanks Eric. -- Regards, Corey Bryant