From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=42182 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PnU1Y-00070y-J7 for qemu-devel@nongnu.org; Thu, 10 Feb 2011 05:45:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PnU1M-0007xp-8h for qemu-devel@nongnu.org; Thu, 10 Feb 2011 05:45:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42263) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PnU1M-0007xB-1Q for qemu-devel@nongnu.org; Thu, 10 Feb 2011 05:45:08 -0500 Date: Thu, 10 Feb 2011 10:44:45 +0000 From: "Daniel P. Berrange" Subject: Re: [Qemu-devel] [PATCH 02/18] Introduce read() to FdMigrationState. Message-ID: <20110210104445.GH2842@redhat.com> References: <1297330258-20494-1-git-send-email-tamura.yoshiaki@lab.ntt.co.jp> <1297330258-20494-3-git-send-email-tamura.yoshiaki@lab.ntt.co.jp> <4D53B5B9.8070509@codemonkey.ws> <20110210101856.GE2842@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Reply-To: "Daniel P. Berrange" List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yoshiaki Tamura Cc: kwolf@redhat.com, aliguori@us.ibm.com, mtosatti@redhat.com, ananth@in.ibm.com, kvm@vger.kernel.org, mst@redhat.com, dlaor@redhat.com, qemu-devel@nongnu.org, vatsa@linux.vnet.ibm.com, blauwirbel@gmail.com, ohmura.kei@lab.ntt.co.jp, avi@redhat.com, pbonzini@redhat.com, psuriset@linux.vnet.ibm.com, stefanha@linux.vnet.ibm.com On Thu, Feb 10, 2011 at 07:23:33PM +0900, Yoshiaki Tamura wrote: > 2011/2/10 Daniel P. Berrange : > > On Thu, Feb 10, 2011 at 10:54:01AM +0100, Anthony Liguori wrote: > >> On 02/10/2011 10:30 AM, Yoshiaki Tamura wrote: > >> >Currently FdMigrationState doesn't support read(), and this patch > >> >introduces it to get response from the other side. > >> > > >> >Signed-off-by: Yoshiaki Tamura > >> > >> Migration is unidirectional. =C2=A0Changing this is fundamental and = not > >> something to be done lightly. > > > > Making it bi-directional might break libvirt's save/restore > > to file support which uses migration, passing a unidirectional > > FD for the file. It could also break libvirt's secure tunnelled > > migration support which is currently only expecting to have > > data sent in one direction on the socket. >=20 > Hi Daniel, >=20 > IIUC, this patch isn't something to make existing live migration > bi-directional. Just opens up a way for Kemari to use it. Do > you think it's dangerous for libvirt still? The key is for it to be a no-op for any usage of the existing 'migrate' command. I had thought this was wiring up read into the event loop too, so it would be poll()ing for reads, but after re-reading I see this isn't the case here. Regards, Daniel --=20 |: http://berrange.com -o- http://www.flickr.com/photos/dberrange= / :| |: http://libvirt.org -o- http://virt-manager.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vn= c :|