From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44387) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WsRlH-0005vj-1I for qemu-devel@nongnu.org; Thu, 05 Jun 2014 03:07:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WsRl9-0002I0-Id for qemu-devel@nongnu.org; Thu, 05 Jun 2014 03:06:54 -0400 Received: from oxygen.pond.sub.org ([144.76.244.19]:53124) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WsRl9-0002Hi-Dj for qemu-devel@nongnu.org; Thu, 05 Jun 2014 03:06:47 -0400 Received: from blackfin.pond.sub.org (p5B32BB48.dip0.t-ipconnect.de [91.50.187.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by oxygen.pond.sub.org (Postfix) with ESMTPSA id 2435E2454D for ; Thu, 5 Jun 2014 09:06:43 +0200 (CEST) From: Markus Armbruster References: <538FA3C8.7000108@redhat.com> <20140605001214.GA2639@localhost.localdomain> <538FCDF2.4080409@redhat.com> <20140605020906.GA10963@T430.nay.redhat.com> <538FDC27.3020607@redhat.com> Date: Thu, 05 Jun 2014 09:06:42 +0200 In-Reply-To: <538FDC27.3020607@redhat.com> (Eric Blake's message of "Wed, 04 Jun 2014 20:55:35 -0600") Message-ID: <87ppinesxp.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] active block commit bug? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: Jeff Cody , akong@redhat.com, Fam Zheng , "qemu-devel@nongnu.org" Eric Blake writes: > On 06/04/2014 08:09 PM, Fam Zheng wrote: > >>> Sounds like we have an off-by-one condition if empty files behave >>> differently from other files. We ought to fix that bug (not that your >>> normal guest will ever have a 0-length backing file, but this was what I >>> was trying to use for libvirt's probing of whether active commit is >>> supported) >>> >> >> Yes, agreed, this special case is only going to make management confused. I >> will send a patch to fix this. > > Thanks. > >> >> Eric, is this a good way to probe the active commit? I was expecting full >> instrospection of QMP could do it, but I don't know about the status of that >> piece of work. Amos, any ideas? > > Introspection already missed qemu 2.0 when active commit was added; and > we're close enough to soft freeze for 2.1 that I'm guessing it will miss > 2.1 as well :( Almost certainly. It has non-trivial design issues. To have a chance to make it into 2.x, it needs to be posted for review early in the 2.x cycle. [...]