From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755891AbXKFRKc (ORCPT ); Tue, 6 Nov 2007 12:10:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753459AbXKFRKZ (ORCPT ); Tue, 6 Nov 2007 12:10:25 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:33113 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751063AbXKFRKY (ORCPT ); Tue, 6 Nov 2007 12:10:24 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: "H. Peter Anvin" Cc: Jeremy Fitzhardinge , Linus Torvalds , Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , Mikael Petterson Subject: Re: [GIT PULL] x86 setup: correct booting on 486 (revised) References: <200711050358.lA53wlho003349@tazenda.hos.anvin.org> <472F5941.2060507@zytor.com> <472F61C8.4040300@zytor.com> <472F7D8D.8050505@zytor.com> <472F826E.3050008@goop.org> <472F85F2.6040501@zytor.com> <472FBC83.5060509@goop.org> <472FBF40.1010300@zytor.com> <472FC0F3.10102@goop.org> <472FC401.9020202@zytor.com> <47309389.3080403@goop.org> <47309608.9030200@zytor.com> <47309C85.6030904@goop.org> <47309D98.8080003@zytor.com> Date: Tue, 06 Nov 2007 10:09:23 -0700 In-Reply-To: <47309D98.8080003@zytor.com> (H. Peter Anvin's message of "Tue, 06 Nov 2007 09:00:08 -0800") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) 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 "H. Peter Anvin" writes: > Jeremy Fitzhardinge wrote: >> H. Peter Anvin wrote: >>> .notes : { >>> *(.note.*) >>> . = ALIGN(4); >>> LONG(0); >>> LONG(0); >>> LONG(0); >>> } >>> >>> Am I missing something? >> >> Oh, I suppose, but I never much liked putting data-definition into the >> linker script. >> > > I think it should be sparsely used, but stuff like simple end markers is pretty > much what it's good for. > > The main reason I want to avoid adding another header field is that the header > is a finite resource; one of the many poor decisions in its original design was > using a 2-byte jump at the top, so address 0x281 is the end of the universe. That was fixed long ago (by having a 4 byte reserved field in the middle) that we can do a two byte jump and then do a farther jump from there to the 16bit code. So as long as we actually use discipline and really reserve the field for a further jump there should be no need for 0x281 being the end of the universe. Eric