Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751102AbWHUVDc (ORCPT ); Mon, 21 Aug 2006 17:03:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751103AbWHUVDc (ORCPT ); Mon, 21 Aug 2006 17:03:32 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:178 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751102AbWHUVDb (ORCPT ); Mon, 21 Aug 2006 17:03:31 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Magnus Damm Cc: fastboot@lists.osdl.org, linux-kernel@vger.kernel.org, ak@suse.de Subject: Re: [PATCH][RFC] x86_64: Reload CS when startup_64 is used. References: <20060821095328.3132.40575.sendpatchset@cherry.local> Date: Mon, 21 Aug 2006 15:02:58 -0600 In-Reply-To: <20060821095328.3132.40575.sendpatchset@cherry.local> (Magnus Damm's message of "Mon, 21 Aug 2006 18:54:16 +0900 (JST)") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) 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 Content-Length: 1386 Lines: 30 Magnus Damm writes: > x86_64: Reload CS when startup_64 is used. > > The current x86_64 startup code never reloads CS during the early boot process > if the 64-bit function startup_64 is used as entry point. The 32-bit entry > point startup_32 does the right thing and reloads CS, and this is what most > people are using if they use bzImage. > > This patch fixes the case when the Linux kernel is booted into using kexec > under Xen. The Xen hypervisor is using large CS values which makes the x86_64 > kernel fail - but only if vmlinux is booted, bzImage works well because it > is using the 32-bit entry point. > > The main question is if we require that the boot loader should setup CS > to some certain offset to be able to boot the kernel. The sane solution IMO > should be that the kernel requires that the loaded descriptors are correct, > but that the exact offset within the GDT the boot loader is using should not > matter. This is the way the i386 boot works if I understand things correctly. What extra reload of cs does Xen introduce? I'm not really comfortable with a half virtualized case. Eric - 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/