From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:33104) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWrh2-00059k-Rj for qemu-devel@nongnu.org; Tue, 22 May 2012 12:12:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SWrgz-0008B9-F7 for qemu-devel@nongnu.org; Tue, 22 May 2012 12:12:16 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:59307) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWrgz-0008A2-5O for qemu-devel@nongnu.org; Tue, 22 May 2012 12:12:13 -0400 Message-ID: <4FBBBAE1.9030808@rdsoftware.de> Date: Tue, 22 May 2012 18:12:17 +0200 From: Erik Rull MIME-Version: 1.0 References: <4FBA735D.4010701@rdsoftware.de> <4FBB6BD1.9080003@siemens.com> <4FBB8647.4060307@siemens.com> In-Reply-To: <4FBB8647.4060307@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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: Jan Kiszka Cc: "qemu-devel@nongnu.org" , Stefan Hajnoczi , Marcelo Tosatti , Avi Kivity , Gerd Hoffmann Jan Kiszka wrote: > 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 > Hi all, thanks a lot! I don't use PCI device assignment - so the missing irqchip-default-option should be the biggest difference between these two versions, right? Best regards, Erik