From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55106) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1borAw-0005HY-S9 for qemu-devel@nongnu.org; Tue, 27 Sep 2016 08:07:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1borAs-00049n-E9 for qemu-devel@nongnu.org; Tue, 27 Sep 2016 08:07:54 -0400 Date: Tue, 27 Sep 2016 08:07:25 -0400 (EDT) From: Paolo Bonzini Message-ID: <2133222015.3059876.1474978044995.JavaMail.zimbra@redhat.com> In-Reply-To: <61b997ac-f9b9-37a2-6a0b-412ad77ddedd@virtuozzo.com> References: <1474893981-5302-1-git-send-email-vsementsov@virtuozzo.com> <27bd2bc9-b879-81ef-c7b6-31335e6be84f@virtuozzo.com> <912490881.3041685.1474971311025.JavaMail.zimbra@redhat.com> <61b997ac-f9b9-37a2-6a0b-412ad77ddedd@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] proto: add 'shift' extension. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" Cc: Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org, nbd-general@lists.sourceforge.net, alex@alex.org.uk, eblake@redhat.com, kwolf@redhat.com, stefanha@redhat.com, w@uter.be ----- Original Message ----- > From: "Denis V. Lunev" > To: "Paolo Bonzini" > Cc: "Vladimir Sementsov-Ogievskiy" , qemu-devel@nongnu.org, qemu-block@nongnu.org, > nbd-general@lists.sourceforge.net, alex@alex.org.uk, eblake@redhat.com, kwolf@redhat.com, stefanha@redhat.com, > w@uter.be > Sent: Tuesday, September 27, 2016 12:25:54 PM > Subject: Re: [PATCH] proto: add 'shift' extension. > > On 09/27/2016 01:15 PM, Paolo Bonzini wrote: > >> We could go in a different direction and export flag > >> 'has_zero_init' which will report that the storage is > >> initialized with all zeroes at the moment. In this > >> case mirroring code will not fall into this > >> branch. > > Why don't you add the zero_init flag to QEMU's NBD driver instead? > > for all cases without knowing real backend on the server side? > I think this would be wrong. Add it to the command line, and leave it to libvirt or the user to pass "-drive file.driver=nbd,...,file.zero-init=on". Paolo