Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757897AbYJGWbe (ORCPT ); Tue, 7 Oct 2008 18:31:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755947AbYJGWbJ (ORCPT ); Tue, 7 Oct 2008 18:31:09 -0400 Received: from mga01.intel.com ([192.55.52.88]:10260 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755381AbYJGWbH (ORCPT ); Tue, 7 Oct 2008 18:31:07 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.33,375,1220252400"; d="scan'208";a="388772926" From: "Nakajima, Jun" To: "H. Peter Anvin" CC: "akataria@vmware.com" , Jeremy Fitzhardinge , "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" Date: Tue, 7 Oct 2008 15:30:10 -0700 Subject: RE: [RFC] CPUID usage for interaction between Hypervisors and Linux. Thread-Topic: [RFC] CPUID usage for interaction between Hypervisors and Linux. Thread-Index: AckluaB72BLlsHRcTbeq450OBusaKQAAaQqQ Message-ID: <0B53E02A2965CE4F9ADB38B34501A3A15DE4F934@orsmsx505.amr.corp.intel.com> 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> In-Reply-To: <48E6BA5B.2090804@zytor.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by alpha id m97MVtdq019015 Content-Length: 1301 Lines: 22 On 10/3/2008 5:35:39 PM, H. Peter Anvin wrote: > Nakajima, Jun wrote: > > > > What's the significance of supporting multiple interfaces to the > > same guest simultaneously, i.e. _runtime_? We don't want the guests > > to run on such a literarily Frankenstein machine. And practically, > > such testing/debugging would be good only for Halloween :-). > > > > By that notion, EVERY CPU currently shipped is a "Frankenstein" CPU, > since at very least they export Intel-derived and AMD-derived interfaces. > This is in other words, a ridiculous claim. The big difference here is that you could create a VM at runtime (by combining the existing interfaces) that did not exist before (or was not tested before). For example, a hypervisor could show hyper-v, osx-v (if any), linux-v, etc., and a guest could create a VM with hyper-v MMU, osx-v interrupt handling, Linux-v timer, etc. And such combinations/variations can grow exponentially. Or are you suggesting that multiple interfaces be _available_ to guests at runtime but the guest chooses one of them? > -hpa > . Jun Nakajima | Intel Open Source Technology Center ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?