Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262191AbTELPXA (ORCPT ); Mon, 12 May 2003 11:23:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262211AbTELPXA (ORCPT ); Mon, 12 May 2003 11:23:00 -0400 Received: from delta.ds2.pg.gda.pl ([213.192.72.1]:39125 "EHLO delta.ds2.pg.gda.pl") by vger.kernel.org with ESMTP id S262191AbTELPW7 (ORCPT ); Mon, 12 May 2003 11:22:59 -0400 Date: Mon, 12 May 2003 17:36:23 +0200 (MET DST) From: "Maciej W. Rozycki" To: "Eric W. Biederman" cc: Davide Libenzi , Linux Kernel Mailing List Subject: Re: [PATCH] Use correct x86 reboot vector In-Reply-To: Message-ID: Organization: Technical University of Gdansk 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 Content-Length: 1483 Lines: 31 On 11 May 2003, Eric W. Biederman wrote: > There is some software at least that knows the difference. I have seen short > jumps in a couple of BIOS's. But a reset is very different from a > reboot. As memory must be reinitialized etc. So I think going to > 0xffff0000:0xfff0 would be a very bad idea if the intent is to get a > reliable reboot. You may change a bit in the i8042 controller to make a BIOS assume that's a cold boot. The bit is zeroed (IIRC; apply a complement if my memory is bad) upon a system RESET that's propagated to the i8042 (i.e. a power-on or a button reset, but not a triple-fault or i8042 output port or port 0x92, etc. one). The bit is set to one by a BIOS during POST and never zeroed afterwards, but it's r/w, so there is no problem to clear it if needed. This should be quite a reliable way to reboot as a BIOS is assumed to initialize hardware from scratch (regardless of the reset vector used). This assumes 100% PC/AT compatibility, of course, which need not be true these days any longer. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available + - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/