From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:40936) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7o4m-0007Fa-7G for qemu-devel@nongnu.org; Wed, 14 Mar 2012 09:17:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S7o4g-0003HD-Li for qemu-devel@nongnu.org; Wed, 14 Mar 2012 09:17:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38716) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7o4g-0003Gz-E7 for qemu-devel@nongnu.org; Wed, 14 Mar 2012 09:17:06 -0400 Date: Wed, 14 Mar 2012 13:17:01 +0000 From: "Daniel P. Berrange" Message-ID: <20120314131701.GF2315@redhat.com> References: <1331483977-18910-1-git-send-email-alevy@redhat.com> <1331494004-26177-1-git-send-email-alevy@redhat.com> <1331494004-26177-5-git-send-email-alevy@redhat.com> <20120313103555.0ae4b834@doriath.home> <20120313144514.GK27659@garlic.redhat.com> <4F605376.1050703@redhat.com> <20120314083713.GA26510@redhat.com> <20120314093258.4bdbc0a3@doriath.home> <20120314131410.GE27659@garlic.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20120314131410.GE27659@garlic.redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 4/5] console: pass Monitor to vga_hw_screen_dump/hw_vga_dump Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino , aliguori@us.ibm.com, Gerd Hoffmann , qemu-devel@nongnu.org On Wed, Mar 14, 2012 at 03:14:10PM +0200, Alon Levy wrote: > On Wed, Mar 14, 2012 at 09:32:58AM -0300, Luiz Capitulino wrote: > > On Wed, 14 Mar 2012 08:37:13 +0000 > > "Daniel P. Berrange" wrote: > > > > > > First, with this applied you will not know the size in advance. Also > > > > one of the approaches discussed is to allow passing in a file handle. > > > > That is a possible way to handle async screendumps too: just write to > > > > the passed file handle and close it when done. Obvious drawback is that > > > > this will not cover the classic way of specifying the output filename as > > > > argument. > > > > As Daniel explains below, this is not a drawback and there's no problem > > supporting multiple ways of returning the image. > > > > The real drawback of making this w/o async support is that you can't detect > > errors. > > > > You also can't detect when the writing is done (unless you continuously > try to parse the file yourself..) That's one of the nice benefits of using a pipe - you'll just get EOF when reading from it, when QEMU is done. > > > > This would not be a problem from libvirt's POV - we don't really want a > > > file on disk anyway, nor do we want to pull the whole image into memory. > > > Our ideal approach is to just have an pipe FD with QEMU, which we just > > > incrementally read image data from, and forward to the client app via > > > a libvirt stream object. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|