From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754474AbXKESdR (ORCPT ); Mon, 5 Nov 2007 13:33:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752358AbXKESdF (ORCPT ); Mon, 5 Nov 2007 13:33:05 -0500 Received: from terminus.zytor.com ([198.137.202.10]:39832 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751112AbXKESdE (ORCPT ); Mon, 5 Nov 2007 13:33:04 -0500 Message-ID: <472F61C8.4040300@zytor.com> Date: Mon, 05 Nov 2007 10:32:40 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Linus Torvalds CC: Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , Mikael Petterson , Eric Biederman , Jeremy Fitzhardinge Subject: Re: [GIT PULL] x86 setup: correct booting on 486 (revised) References: <200711050358.lA53wlho003349@tazenda.hos.anvin.org> <472F5941.2060507@zytor.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 X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds wrote: > > Final comment: shouldn't we set up %esp to be correct for the new %ss too? > Well, the 32-bit code needs to set up its own stack, and only it knows where it wants its stack; we don't guarantee that the stack is valid when we enter the 32-bit code and we're entering with both INT and NMI disabled (requiring a stack would probably break all existing users of the 32-bit entrypoint.) However, that being said, doing so is trivial, and it might help some debugging hack; anything that makes debugging easier is a Good Thing[TM]. -hpa