From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:54927) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWoC5-0004RA-35 for qemu-devel@nongnu.org; Tue, 22 May 2012 08:28:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SWoBz-0004sQ-Lg for qemu-devel@nongnu.org; Tue, 22 May 2012 08:28:04 -0400 Received: from goliath.siemens.de ([192.35.17.28]:22662) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWoBz-0004rp-Bk for qemu-devel@nongnu.org; Tue, 22 May 2012 08:27:59 -0400 Message-ID: <4FBB8647.4060307@siemens.com> Date: Tue, 22 May 2012 09:27:51 -0300 From: Jan Kiszka MIME-Version: 1.0 References: <4FBA735D.4010701@rdsoftware.de> <4FBB6BD1.9080003@siemens.com> In-Reply-To: <4FBB6BD1.9080003@siemens.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Current differences between qemu --enable-kvm and qemu-kvm? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Avi Kivity , Erik Rull , Gerd Hoffmann , "qemu-devel@nongnu.org" , Marcelo Tosatti On 2012-05-22 07:34, Jan Kiszka wrote: > On 2012-05-22 07:04, Stefan Hajnoczi wrote: >> On Mon, May 21, 2012 at 5:54 PM, Erik Rull wrote: >>> is there a summary existing that shows up the rough or actual differences >>> between qemu --enable-kvm and qemu-kvm? I tested both versions with the same >>> compile and start options, the CPU performance results are identical, only >>> the bootup time of my guest system with qemu-kvm seemed to be a bit faster >>> (not measured, it just feeled so). > > Current upstream does not enable the in-kernel irqchip of KVM by > default. This should explain the difference in boot-up times. Try > "-machine accel=kvm,kernel_irqchip=on". But the default will be on, just > like in qemu-kvm, once [1] is merged. > >> >> For production KVM instances I think it still makes sense to use >> qemu-kvm packages from your distro or qemu-kvm upstream source. >> >> Jan Kiszka has reduced the delta between qemu.git and qemu-kvm.git to >> the point where I think the list of differences is rather small - >> maybe PCI passthrough stuff, irqfd for vhost-net (which is now also >> being upstreamed into qemu.git), and a few other things I don't know >> of. > > Right, the list of differences is dramatically shrinking. As stated in > [2], soon only PCI passthrough and legacy interface dependencies on > qemu-kvm will be the remaining reasons to use it. If we are lucky, PCI > passthrough will also make it into upstream for QEMU 1.2, we are working > on this. > >> >> For development most patches should be against qemu.git unless they >> have a dependency on qemu-kvm.git code. > > Yes, unless you are working on the upstream merge itself, there is > practically no reason anymore to develop against qemu-kvm directly. > > Jan > > [1] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/91171 > [2] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/91026 > I've added some more details on this to the QEMU wiki, see http://wiki.qemu.org/KVM. BTW, if someone could have a look at the VGA diffs and resolve them, that would be great. Gerd, what's the state of switching the BIOS? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux