From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271AbZDLRyo (ORCPT ); Sun, 12 Apr 2009 13:54:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752043AbZDLRyf (ORCPT ); Sun, 12 Apr 2009 13:54:35 -0400 Received: from terminus.zytor.com ([198.137.202.10]:38399 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978AbZDLRye (ORCPT ); Sun, 12 Apr 2009 13:54:34 -0400 Message-ID: <49E22A2D.6010009@zytor.com> Date: Sun, 12 Apr 2009 10:51:41 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Linus Torvalds CC: Avi Kivity , Pavel Machek , Ingo Molnar , mingo@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com, rjw@sisk.pl, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/setup] x86, setup: "glove box" BIOS calls -- infrastructure References: <49DE7F79.4030106@zytor.com> <20090410080444.GC16512@elf.ucw.cz> <20090410103934.GA21506@elte.hu> <20090410104648.GA31516@elf.ucw.cz> <20090410112546.GD21506@elte.hu> <20090410113824.GA18823@elf.ucw.cz> <49E0C1AB.2050608@redhat.com> <49E17A6E.5000104@zytor.com> In-Reply-To: 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 Linus Torvalds wrote: > > This discussion is just taking us down a rat-hole of more complexity, and > _way_ more fragility. > > I'm absolutely willing to bet that trying to do the BIOS calls will break > way more than it will fix. Sure, it will probably work for 99.9% of all > BIOSes, but then it will break horribly for some BIOS that tries to do > something "clever". SMM has already been mentioned as an example of > something that simply isn't virtualizable. > > Timing is another, very traditional, one. There used to be video BIOSes > that simply didn't work in a dosbox-like environment because they had > tight timing loops that were coupled to hardware. I can pretty much > guarantee that that has gone away as far as the video BIOS is concerned, > but the main BIOS? Who the hell knows. > > Sure, none of the calls we do to the BIOS from the kernel should need > anything fancy at all, and maybe I'm pessimistic. But at the same time, I > really don't think the BIOS calls are worth that kind of infrastructure. > > Sure, go ahead and wrap them in some kind of "save and restore all > registers" wrapping, but nothing fancier than that. It would just be > overkill, and likely to break more than it fixes. > Agreed completely. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.