From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: Re: Integrate kqemu emulation into xen hypervisor possible? Date: Tue, 1 Apr 2008 19:23:51 +0100 Message-ID: <20080401182351.GE31765@redhat.com> References: <20080401154852.GI4637@implementation.nationalexpresswifi.train> <20080401105036421.00000002504@djm-pc> Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <20080401105036421.00000002504@djm-pc> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: "Ross S. W. Walker" , "xen-devel@lists.xensource.com" , Samuel Thibault List-Id: xen-devel@lists.xenproject.org On Tue, Apr 01, 2008 at 10:50:36AM -0600, Dan Magenheimer wrote: > > Ross S. W. Walker, le Tue 01 Apr 2008 11:41:24 -0400, a =E9crit : > > > Samuel Thibault wrote: > > > > Ross S. W. Walker, le Tue 01 Apr 2008 11:19:35 -0400, a =E9crit : > > > > > I was wondering if now that the kqemu source has been=20 > > GPL'd if it was > > > > > possible if it's functionality could be incorporated=20 > > into the Xen > > > > > hypervisor to provide full virtualization on hardware=20 > > that doesn't > > > > > support it? > > > > > > > > What would be the benefit, compared to just running qemu in > > > > user space? > >=20 > > Oooh, oops, you are talking about *k*qemu, not qemu, sorry, ok, I see. > > Well, a first step would be to make kqemu work with Xen's dom0 Linux. > > Then, adding the feature in the Hypervisor may make sense indeed, but > > I'm not sure you'd get much bigger performance than with just the dom= 0 > > support. >=20 > If I'm not misunderstanding, an interesting side effect of this > would be recursive virtual machines, e.g. Xen could run Xen running > an hvm. >=20 > Who cares about such a thing in the real world, you ask? > Probably not particularly useful in production, but it > would be useful in education and debugging. >=20 > On the other hand, kqemu isn't really needed for that, just full > emulation of the VT instruction set, correct? Indeed that is correct - atlhough I've not tried it out, upstream QEMU do= es already emulate the SVM instructions which should allow Xen / KVM to do fullyvirt. > What kqemu-in-xen *could* be used for would be running x86 VMs on > a non-x86 architecture! (Insert shameless plug for googling > MagiXen here :-) No it can't - AFAIK kqemu is for matched host-guest arch only. Only plain emulated QEMU can do mixed host-guest archiecture, and it cannot take advantage of kqemu when doing this emulation. Dan. --=20 |: Red Hat, Engineering, Boston -o- http://people.redhat.com/berrange= / :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 950= 5 :|