From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: Xen & VMI? Date: Tue, 06 Mar 2007 09:03:53 -0600 Message-ID: <45ED82D9.6050204@codemonkey.ws> References: <45ECC91D.1020809@vmware.com> <45ECC9B6.1060209@goop.org> <20070306081909.GA9331@elte.hu> <45ED2837.3020108@suse.de> <20070306085222.GA17002@elte.hu> <45ED3121.8090308@suse.de> <20070306093436.GA30239@elte.hu> <45ED3F29.6000705@suse.de> <20070306102658.GA7478@elte.hu> <45ED4AD8.6020504@suse.de> <20070306115937.GA25313@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20070306115937.GA25313@elte.hu> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.osdl.org Errors-To: virtualization-bounces@lists.osdl.org To: Ingo Molnar Cc: virtualization , Roland McGrath , Andrew Morton , Linus Torvalds , Jan Beulich , linux-kernel@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org Ingo Molnar wrote: > * Gerd Hoffmann wrote: > = >>>> So in the end you would still have two different hypervisor ABI's, = >>>> the VMI ROM just hides that. >>> oh, but that way i have cleverly pushed the problem out of Linux and = >>> into the VMI-ROM's domain ;) Which is all i care about. >> Fine, so lets move kvm paravirtualitzation into vmi too (proof of = >> concept code by Anthony Liguori exists) and kill one more item on the = >> (linux) QA test matrix? (just following your arguments, not that I'm = >> confident it would actually help reducing QA effort). > = > yes - although obviously a KVM Linux guest does not need such an = > interface - but it's a nice proof of concept to integrate other guest = > OSs into KVM. I disagree that a KVM Linux guest does not benefit from VMI. Right now, = your KVM paravirt interface only covers CR3 target caching and apic = enhancements (neither of which I believe have made it into 2.6.21). = Inevitably, things like MMU batching will be added. Using paravirt_ops, this is going to require new kernels for the guests. = Every new paravirtualization feature will require a new guest kernel. = With VMI, one can add these features to any 2.6.21+ guest by just = modifying the ROM (assuming a newer host). Some features will require = new VMI entry points but quite a lot will fall under the current entry = points. Of all the hypervisors, KVM is the easiest to use VMI with. QEMU = already supports option ROM loading and Zach just made some changes to = allow a native ROM to be implemented very easily. If we're going to use VMI for anything other than VMware, it seems to be = that KVM should be what we use it for. Regards, Anthony Liguori > Ingo