From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1767557AbXCIWOE (ORCPT ); Fri, 9 Mar 2007 17:14:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933410AbXCIWOD (ORCPT ); Fri, 9 Mar 2007 17:14:03 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:55165 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933409AbXCIWOA (ORCPT ); Fri, 9 Mar 2007 17:14:00 -0500 Date: Fri, 9 Mar 2007 23:12:33 +0100 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Chris Wright , Zachary Amsden , Thomas Gleixner , john stultz , akpm@linux-foundation.org, LKML , Rusty Russell , Andi Kleen , Alan Cox Subject: Re: ABI coupling to hypervisors via CONFIG_PARAVIRT Message-ID: <20070309221233.GA24341@elte.hu> References: <20070309180230.GA17988@elte.hu> <20070309192420.GA27747@elte.hu> <20070309210430.GA14905@elte.hu> <20070309212714.GU10574@sequoia.sous-sol.org> <20070309214704.GA20988@elte.hu> <45F1D8D7.9040207@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45F1D8D7.9040207@goop.org> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Jeremy Fitzhardinge wrote: > Now it may be that you've got a change that's absolutely great for > everyone, and the only blocker is that the FoobieVisor can't deal with > it. OK, great, then you'd have a point. yep. That's precisely my worry. And it doesnt have to be a 'great' thing - just any random small change in the kernel that makes sense: what is the likelyhood that it cannot be implemented, no matter what amount of insight, paravirt_ops + hyper-ABI emulation hackery, for FoobieVisor, because FoobieVisor messed up its ABI. that likelyhood is a pure function of how FoobieVisor's hypercall ABI is shaped. Wow! So can you guess where my fixation about not having too many ABIs could possibly originate from? ;-) Until today everyone on the hypervisor side of the argument pretended that paravirt_ops solves all problems and acted stupid when i said an ABI is an ABI is an ABI, and that "backwards compatibility" does have some technological consequences. _Now_ at least i've got this minimal admission that FoobieVisor _might_ break. Quite a breakthrough =B-) Ingo