From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38357) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RDCxw-0006yJ-7b for qemu-devel@nongnu.org; Mon, 10 Oct 2011 06:20:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RDCxp-0003Kx-Vr for qemu-devel@nongnu.org; Mon, 10 Oct 2011 06:20:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32565) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RDCxp-0003JQ-Ke for qemu-devel@nongnu.org; Mon, 10 Oct 2011 06:20:05 -0400 Date: Mon, 10 Oct 2011 11:19:49 +0100 From: "Daniel P. Berrange" Message-ID: <20111010101949.GP9408@redhat.com> References: <4E8ECA91.8040409@cn.fujitsu.com> <4E8ED167.1000705@siemens.com> <20111008151622.GA17181@amd.home.annexia.org> <4E916035.5050906@web.de> <20111009102338.GN16799@amd.home.annexia.org> <4E92568E.2010507@cn.fujitsu.com> <20111010090825.GG9408@redhat.com> <20111010091021.GH9408@redhat.com> <4E92BC34.6090500@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4E92BC34.6090500@siemens.com> Subject: Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: qemu-devel , "Richard W.M. Jones" , Luiz Capitulino On Mon, Oct 10, 2011 at 11:34:44AM +0200, Jan Kiszka wrote: > On 2011-10-10 11:10, Daniel P. Berrange wrote: > > On Mon, Oct 10, 2011 at 10:08:26AM +0100, Daniel P. Berrange wrote: > >> On Mon, Oct 10, 2011 at 10:21:02AM +0800, Wen Congyang wrote: > >>> At 10/09/2011 06:23 PM, Richard W.M. Jones Write: > >>>> On Sun, Oct 09, 2011 at 10:49:57AM +0200, Jan Kiszka wrote: > >>>>> As explained in the other replies: It is way more future-proof to use an > >>>>> interface for this which was designed for it (remote gdb) instead of > >>>>> artificially relaxing reasonable constraints of the migration mechanism > >>>>> plus having to follow that format with the post-processing tool. > >>>> > >>>> Any interface that isn't "get this information off my production > >>>> server *now*" so that I can get the server restarted, and send it to > >>>> an expert to analyse -- is a poor interface, whether it was designed > >>>> like that or not. Perhaps we don't have the right interface at all, > >>>> but remote gdb is not it. > >>> > >>> What about the following idea? > >>> > >>> Introduce a new monitor command named dump, and this command accepts a filename. > >>> We can use almost all migration's code. We use this command to dump guest's > >>> memory, so there is no need to check whether the guest has a unmigratable device. > >> > >> I think it would be a good idea of QEMU had a dedicated 'dump' command > >> for this purpose, even if it was just an alias for 'migrate' initially. > >> I have never really liked the fact that we abuse the 'migrate' command > >> to generate a core dump. The resulting data file from this is more > >> complex than it really needs to be, causing complexity for post-processing > >> it. The needs of migration, are not entirely aligned with the needs of > >> core dumping in the long term, so we should allow the possibility of > >> their impls diverging without impacting apps using them. > >> > >> So adding a 'dump' command which wrote out data in a format that was > >> optimized for offline processing by tools like 'crash' (or the windows > >> equivalent) would be a good improvement, even if it just reuses the > >> migrate code for now. > > > > The other reason why it would be good, is that we would then have a clearly > > defined standard "QEMU dump format", instead of "libvirt dump format for QEMU" > > A core file would be that format - for direct gdb processing. No > proprietary re-inventions please. I have no personal attachment to any particular format, so if the standard core file format is possible, then we should definitely try to use it in QEMU. 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 :|