Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758679AbZIQQqV (ORCPT ); Thu, 17 Sep 2009 12:46:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753047AbZIQQqV (ORCPT ); Thu, 17 Sep 2009 12:46:21 -0400 Received: from claw.goop.org ([74.207.240.146]:58746 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752120AbZIQQqU (ORCPT ); Thu, 17 Sep 2009 12:46:20 -0400 Message-ID: <4AB267DC.50901@goop.org> Date: Thu, 17 Sep 2009 09:46:20 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Lightning/1.0pre Thunderbird/3.0b3 MIME-Version: 1.0 To: Keir Fraser CC: Sheng Yang , Jeremy Fitzhardinge , xen-devel , Eddie Dong , "linux-kernel@vger.kernel.org" , Jun Nakajima Subject: Re: [Xen-devel] [RFC][PATCH 03/10] xen/hybrid: Xen Hybrid Extension initialization References: In-Reply-To: X-Enigmail-Version: 0.97a Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 34 On 09/16/09 23:22, Keir Fraser wrote: >> I think having an option to put PV guests into an HVM container is a >> good one, but as I mentioned in the other mail, I don't think this is >> the right approach. >> >> It would be much better to make it so that an unmodified guest works in >> such a mode; even with no specific optimisations the guest would get >> benefit from faster kernel<->usermode switches. >> > By unmodified you mean ordinary PV guest? Right. > It's an interesting comparison -- > PVing an HVM guest, versus HVMing (to some extent) a PV guest. > KVM is basically using the model of starting with a fully emulated hvm domain, then adding paravirtualizations as incremental extensions to that. If you want to go that route, then we may as well just adopt their interfaces and use the existing kernel support as-is (though their most useful paravirtualization - time - is adopted from Xen's ABI). If we want to get a PV kernel which makes use of hvm features, then we should do the analogous thing in the other direction: use the current PV ABI as baseline, then add small optional extensions to take advantage of the HVM container's features. 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/