From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754551AbXKESiK (ORCPT ); Mon, 5 Nov 2007 13:38:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752585AbXKESh5 (ORCPT ); Mon, 5 Nov 2007 13:37:57 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:54280 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277AbXKESh5 (ORCPT ); Mon, 5 Nov 2007 13:37:57 -0500 Date: Mon, 5 Nov 2007 10:36:50 -0800 (PST) From: Linus Torvalds To: "H. Peter Anvin" 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) In-Reply-To: <472F61C8.4040300@zytor.com> Message-ID: References: <200711050358.lA53wlho003349@tazenda.hos.anvin.org> <472F5941.2060507@zytor.com> <472F61C8.4040300@zytor.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 5 Nov 2007, H. Peter Anvin wrote: > > 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.) I agree. But it would be nice if some basic instructions still worked: as is, you cannot even do things like reloading %eflags, because the only way to do that requires a stack. > 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]. Yeah. Even if it was just re-using the boot-time stack area temporarily, just to give code the choice to use a common set of instructions. Linus