Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758515AbYJGXqV (ORCPT ); Tue, 7 Oct 2008 19:46:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757374AbYJGXpt (ORCPT ); Tue, 7 Oct 2008 19:45:49 -0400 Received: from gw.goop.org ([64.81.55.164]:39448 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756916AbYJGXps (ORCPT ); Tue, 7 Oct 2008 19:45:48 -0400 Message-ID: <48EBF4A7.3080704@goop.org> Date: Tue, 07 Oct 2008 16:45:43 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.16 (X11/20080919) MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Nakajima, Jun" , "akataria@vmware.com" , "avi@redhat.com" , Rusty Russell , Gerd Hoffmann , Ingo Molnar , the arch/x86 maintainers , LKML , Daniel Hecht , Zach Amsden , "virtualization@lists.linux-foundation.org" , "kvm@vger.kernel.org" Subject: Re: [RFC] CPUID usage for interaction between Hypervisors and Linux. References: <1222881242.9381.17.camel@alok-dev1> <48E3B19D.6060905@zytor.com> <1222882431.9381.23.camel@alok-dev1> <48E3BC21.4080803@goop.org> <1222895153.9381.69.camel@alok-dev1> <48E3FDD5.7040106@zytor.com> <0B53E02A2965CE4F9ADB38B34501A3A15D927EA4@orsmsx505.amr.corp.intel.com> <48E422CA.2010606@zytor.com> <0B53E02A2965CE4F9ADB38B34501A3A15DCBA221@orsmsx505.amr.corp.intel.com> <48E6AB15.8060405@zytor.com> <0B53E02A2965CE4F9ADB38B34501A3A15DCBA325@orsmsx505.amr.corp.intel.com> <48E6BA5B.2090804@zytor.com> <0B53E02A2965CE4F9ADB38B34501A3A15DE4F934@orsmsx505.amr.corp.intel.com> <48EBE499.5000304@zytor.com> In-Reply-To: <48EBE499.5000304@zytor.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1222 Lines: 26 H. Peter Anvin wrote: > And you're absolutely right that the guest may end up picking and > choosing different parts of the interfaces. That's how it is supposed > to work. No, that would be a horrible, horrible mistake. There's no sane way to implement that; it would mean that the hypervisor would have to have some kind of state model that incorporates all the ABIs in a consistent way. Any guest using multiple ABIs would effectively end up being dependent on a particular hypervisor via a frankensteinian interface that no other hypervisor would implement in the same way, even if they claim to implement the same set of interfaces. If the hypervisor just needs to deal with one at a time then it can have relatively simple ABI<->internal state translation. However, if you have the notion of hypervisor-agnostic or common interfaces, then you can include those as part of the rest of the ABI and make it sane (so Xen+common, hyperv+common, etc). J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/