From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031075AbXEDQNG (ORCPT ); Fri, 4 May 2007 12:13:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031290AbXEDQNG (ORCPT ); Fri, 4 May 2007 12:13:06 -0400 Received: from gw.goop.org ([64.81.55.164]:50982 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031075AbXEDQNE (ORCPT ); Fri, 4 May 2007 12:13:04 -0400 Message-ID: <463B5B90.20308@goop.org> Date: Fri, 04 May 2007 09:13:04 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Eric W. Biederman" , Rusty Russell , Andi Kleen , Chris Wright , Zachary Amsden , Andrew Morton , Linus Torvalds , lkml - Kernel Mailing List Subject: Re: [RFC PATCH 3/3] boot bzImages under paravirt References: <1178283582.23670.67.camel@localhost.localdomain> <1178283724.23670.70.camel@localhost.localdomain> <1178284052.23670.75.camel@localhost.localdomain> <463B4E12.50703@goop.org> <463B551E.8030701@zytor.com> In-Reply-To: <463B551E.8030701@zytor.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > In 32-bit mode? Surely you're joking, Mr. Feynman! > Right, yes. > What's worse, reloading segments here might be highly unsafe, if the > memory previously occupied by the GDT has been overwritten. Keep in > mind the GDT is touched on a segment *load*, not on a segment *access*; > in areas such as booting that can be a huge difference. > Yep, suits me. I'm happy for the code to assume that at least %cs and %ds are sane; I guess %ss too. We could copy %ds into %[efg]s if we want to be sure (since I could imagine a bootloader leaving them in a less defined state). But if the gdt could be missing altogether, then, yes, we should not touch them at all. J