From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:54095) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S66z4-0003OD-Uz for qemu-devel@nongnu.org; Fri, 09 Mar 2012 16:04:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S66z2-0006oi-GA for qemu-devel@nongnu.org; Fri, 09 Mar 2012 16:04:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56830) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S66z2-0006jl-8Q for qemu-devel@nongnu.org; Fri, 09 Mar 2012 16:04:16 -0500 Date: Fri, 9 Mar 2012 21:04:03 +0000 From: "Daniel P. Berrange" Message-ID: <20120309210403.GA2319@redhat.com> References: <20111218095816.GG21664@redhat.com> <20120309205652.GA6807@otherpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20120309205652.GA6807@otherpad.lan.raisama.net> Subject: Re: [Qemu-devel] [libvirt] Modern CPU models cannot be used with libvirt Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: libvir-list@redhat.com, qemu-devel@nongnu.org, Gleb Natapov , Anthony Liguori , Jiri Denemark , Avi Kivity On Fri, Mar 09, 2012 at 05:56:52PM -0300, Eduardo Habkost wrote: > Resurrecting an old thread: > > I didn't see any clear conclusion in this thread (this is why I am > resurrecting it), except that many were arguing that libvirt should > simply copy and/or generate the CPU model definitions from Qemu. I > really don't think it's reasonable to expect that. > > On Thu, Dec 15, 2011 at 03:54:15PM +0100, Jiri Denemark wrote: > > Hi, > > > > Recently I realized that all modern CPU models defined in > > /etc/qemu/target-x86_64.conf are useless when qemu is used through libvirt. > > That's because we start qemu with -nodefconfig which results in qemu ignoring > > that file with CPU model definitions. We have a very good reason for using > > -nodefconfig because we need to control the ABI presented to a guest OS and we > > don't want any configuration file that can contain lots of things including > > device definitions to be read by qemu. However, we would really like the new > > CPU models to be understood by qemu even if used through libvirt. What would > > be the best way to solve this? > > > > I suspect this could have been already discussed in the past but obviously a > > workable solution was either not found or just not implemented. > > So, our problem today is basically: > > A) libvirt uses -nodefconfig; > B) -nodefconfig makes Qemu not load the config file containing the CPU > model definitions; and > C) libvirt expects the full CPU model list from Qemu to be available. I could have sworn we had this discussion a year ago or so, and had decided that the default CPU models would be in something like /usr/share/qemu/cpu-x86_64.conf and loaded regardless of the -nodefconfig setting. /etc/qemu/target-x86_64.conf would be solely for end user configuration changes, not for QEMU builtin defaults. But looking at the code in QEMU, it doesn't seem we ever implemented this ? 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 :|