From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758064AbZCBJcz (ORCPT ); Mon, 2 Mar 2009 04:32:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756859AbZCBJcq (ORCPT ); Mon, 2 Mar 2009 04:32:46 -0500 Received: from mx2.redhat.com ([66.187.237.31]:37780 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756783AbZCBJcp (ORCPT ); Mon, 2 Mar 2009 04:32:45 -0500 Message-ID: <49ABA633.2050903@redhat.com> Date: Mon, 02 Mar 2009 10:26:11 +0100 From: Gerd Hoffmann User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Ingo Molnar CC: Jeremy Fitzhardinge , Andrew Morton , "H. Peter Anvin" , the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel Subject: Re: [PATCH] xen: core dom0 support References: <1235786365-17744-1-git-send-email-jeremy@goop.org> <20090227212812.26d02f34.akpm@linux-foundation.org> <49A8DF28.4050301@goop.org> <20090228072055.GC9351@elte.hu> In-Reply-To: <20090228072055.GC9351@elte.hu> 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 Ingo Molnar wrote: >>> In three years time, will we regret having merged this? >> Its a pretty minor amount of extra stuff on top of what's been >> added over the last 3 years, so I don't think it's going to >> tip the scales on its own. I wouldn't be comfortable in >> trying to merge something that's very intrusive. > > Hm, how can the same code that you call "massive out-of-tree > patches which doesn't make anyone happy" in an out of tree > context suddenly become non-intrusive "minor amount of extra > stuff" in an upstream context? The current, out-of-tree xen kernel stuff is based on 2.6.18. That predates pv_ops and is quite intrusive stuff, with alot of cut+paste programming and dirty hacks. Alot has happened in x86 land since 2.6.18. Being one of the x86 arch maintainers you should know that very well. Most notably: * pv_ops. Point of adding these is to allow virtualization-friendly kernels *without* being intrusive as hell. * x86 arch merge, followed up by tons of cleanups and code reorganizations. These changes also make it easier to merge xen support in a non-intrusive manner. Also the xen support code in the linux kernel itself is basically a rewrite from scratch, it hasn't much in common with the 2.6.18 code base. > I wish the upstream kernel was able to do such magic, but i'm > afraid it is not. It's no magic, it's alot of hard work. cheers, Gerd