Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752611AbZFBTGe (ORCPT ); Tue, 2 Jun 2009 15:06:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751052AbZFBTG1 (ORCPT ); Tue, 2 Jun 2009 15:06:27 -0400 Received: from mx2.redhat.com ([66.187.237.31]:55997 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776AbZFBTG0 (ORCPT ); Tue, 2 Jun 2009 15:06:26 -0400 Message-ID: <4A257687.2030801@redhat.com> Date: Tue, 02 Jun 2009 21:59:19 +0300 From: Avi Kivity User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Linus Torvalds CC: George Dunlap , Thomas Gleixner , David Miller , "jeremy@goop.org" , "mingo@elte.hu" , Dan Magenheimer , "xen-devel@lists.xensource.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Keir Fraser , "gregkh@suse.de" , "kurt.hackel@oracle.com" , Ian Pratt , "xen-users@lists.xensource.com" , ksrinivasan , "EAnderson@novell.com" , "wimcoekaerts@wimmekes.net" , Stephen Spector , "jens.axboe@oracle.com" , "npiggin@suse.de" Subject: Re: Xen is a feature References: <162f4c90-6431-4a2a-b337-6d7451d7b11e@default> <20090528001350.GD26820@elte.hu> <4A1F302E.8030501@goop.org> <20090528.210559.137121893.davem@davemloft.net> <4A1FCE8E.2060604@eu.citrix.com> <4A25564A.70608@eu.citrix.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; 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: 1794 Lines: 36 Linus Torvalds wrote: > The point? Xen really is horribly badly separated out. It gets way more > incestuous with other systems than it should. It's entirely possible that > this is very fundamental to both paravirtualization and to hypervisor > behavior, but it doesn't matter - it just measn that I can well see that > Xen is a f*cking pain to merge. > > So please, Xen people, look at your track record, and look at the issues > from the standpoint of somebody merging your code, rather than just from > the standpoint of somebody who whines "I want my code to be merged". > > IOW, if you have trouble getting your code merged, ask yourself what _you_ > are doing wrong. > There is in fact a way to get dom0 support with nearly no changes to Linux, but it involves massive changes to Xen itself and requires hardware support: run dom0 as a fully virtualized guest, and assign it all the resources dom0 can access. It's probably a massive effort though. I've considered it for kvm when faced with the "I want a thin hypervisor" question: compile the hypervisor kernel with PCI support but nothing else (no CONFIG_BLOCK or CONFIG_NET, no device drivers), load userspace from initramfs, and assign host devices to one or more privileged guests. You could probably run the host with a heavily stripped configuration, and enjoy the slimness while every interrupt invokes the scheduler, a context switch, and maybe an IPI for good measure. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. -- 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/