Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261797AbTEKRYO (ORCPT ); Sun, 11 May 2003 13:24:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261798AbTEKRYO (ORCPT ); Sun, 11 May 2003 13:24:14 -0400 Received: from x35.xmailserver.org ([208.129.208.51]:40850 "EHLO x35.xmailserver.org") by vger.kernel.org with ESMTP id S261797AbTEKRYN (ORCPT ); Sun, 11 May 2003 13:24:13 -0400 X-AuthUser: davidel@xmailserver.org Date: Sun, 11 May 2003 10:38:49 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@blue1.dev.mcafeelabs.com To: Jamie Lokier cc: Jos Hulzink , Linus Torvalds , Andi Kleen , Linux Kernel Mailing List Subject: Re: [PATCH] Use correct x86 reboot vector In-Reply-To: <20030511140144.GA5602@mail.jlokier.co.uk> Message-ID: References: <200305111137.29743.josh@stack.nl> <20030511140144.GA5602@mail.jlokier.co.uk> 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: 1399 Lines: 32 On Sun, 11 May 2003, Jamie Lokier wrote: > Jos Hulzink wrote: > > On Sunday 11 May 2003 05:50, Linus Torvalds wrote: > > > Hmm.. Doesnt' a _real_ hardware reset actually use a magic segment that > > > isn't even really true real mode? I have this memory that the reset value > > > for a i386 has CS=0xf000, but the shadow base register actually contains > > > 0xffff0000. In other words, the CPU actually starts up in "unreal" mode, > > > and will fetch the first instruction from physical address 0xfffffff0. > > > > > > At least that was true on an original 386. It's something that could > > > easily have changed since. > > I got my info from an article on the net which says that a 386 does > behave as you say, but it is possible for the system designer to > arrange that it boots into the 286-compatible vector at physical > address 0x000ffff0. It states that the feature is specifically so > that system designers don't have to create a "memory hole" (that's as > much detail as it gives). Guys, mem[0xfffffff0,...] == mem[0x000ffff0,...] since the hw remaps the bios. Being picky about Intel specs, it should be f000:fff0 though. - Davide - 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/