From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933606Ab3GSSrJ (ORCPT ); Fri, 19 Jul 2013 14:47:09 -0400 Received: from terminus.zytor.com ([198.137.202.10]:46721 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752697Ab3GSSrI (ORCPT ); Fri, 19 Jul 2013 14:47:08 -0400 Message-ID: <51E989A0.8050103@zytor.com> Date: Fri, 19 Jul 2013 11:46:56 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Ramkumar Ramachandra CC: LKML , Rusty Russell Subject: Re: [QUERY] lguest64 References: <51E97779.3020103@zytor.com> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/19/2013 10:42 AM, Ramkumar Ramachandra wrote: > H. Peter Anvin wrote: >> We want to reduce pvops and pvops users, not increase them... > > I see. So the future is true virtualization which exposes the > underlying hardware, like KVM? Why do bare-metal virtualizers like > Xen employ paravirtualization? Also, where does UML stand? > UML, lguest and Xen were done before the x86 architecture supported hardware virtualization. UML does paravirtualization without needing hooks all over the kernel, which is really impressive, but unfortunately rather slow, which makes it useful mostly for testing. I did at some point wonder if UML would make a decent base platform for something similar to libguestfs, but on KVM-enabled hardware KVM seems like the better option (and is indeed what libguestfs uses.) -hpa