From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965259AbXCOF2w (ORCPT ); Thu, 15 Mar 2007 01:28:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965338AbXCOF2w (ORCPT ); Thu, 15 Mar 2007 01:28:52 -0400 Received: from koto.vergenet.net ([210.128.90.7]:42595 "EHLO koto.vergenet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965259AbXCOF2v (ORCPT ); Thu, 15 Mar 2007 01:28:51 -0400 Date: Thu, 15 Mar 2007 14:07:56 +0900 From: Horms To: Vivek Goyal Cc: Ian Campbell , hbabu@us.ibm.com, fastboot@lists.osdl.org, linux-kernel@vger.kernel.org, Magnus Damm Subject: Re: [PATCH 1/1] Allow i386 crash kernels to handle x86_64 dumps Message-ID: <20070315050754.GB22329@verge.net.au> References: <1173891609.8591.41.camel@localhost.localdomain> <20070315014635.GC28396@verge.net.au> <20070315045536.GA6766@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070315045536.GA6766@in.ibm.com> User-Agent: mutt-ng/devel-r804 (Debian) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 15, 2007 at 10:25:36AM +0530, Vivek Goyal wrote: > On Thu, Mar 15, 2007 at 10:46:38AM +0900, Horms wrote: > > On Wed, Mar 14, 2007 at 05:00:09PM +0000, Ian Campbell wrote: > > > The specific case I am encountering is kdump under Xen with a 64 bit > > > hypervisor and 32 bit kernel/userspace. The dump created is a 64 bit due > > > to the hypervisor but the dump kernel is 32 bit to match the domain 0 > > > kernel. > > > > > > It's possibly less likely to be useful in a purely native scenario but I > > > see no reason to disallow it. > > > > For native Linux, would this cover the case where the pre-crash kernel > > is 64bit and the crashdump (post-crash) kernel is 32bit? > > > > I think so. Though I have never tried this. > > > > Signed-off-by: Ian Campbell > > > > > > --- pristine-linux-2.6.18/include/asm-i386/elf.h 2006-09-20 04:42:06.000000000 +0100 > > > +++ linux-2.6.18-xen/include/asm-i386/elf.h 2007-03-14 16:42:30.000000000 +0000 > > > @@ -36,7 +36,7 @@ > > > * This is used to ensure we don't load something for the wrong architecture. > > > */ > > > #define elf_check_arch(x) \ > > > - (((x)->e_machine == EM_386) || ((x)->e_machine == EM_486)) > > > + (((x)->e_machine == EM_386) || ((x)->e_machine == EM_486) || ((x)->e_machine == EM_X86_64)) > > But I think changing this macro might run into issues. It is being used at > few places in kernel, for example while loading module. This will essentially > mean that we allow loading 64bit x86_64 modules on 32bit i386 systems? > > Similarly, load_elf_interp() is using it, again will we allow loading a > interp written for X86_64 on a 32bit i386 machine? > > Should we create a separate macro something like elf_check_allowed_arch(), > to take care of such corner cases? That sounds reasonable to me. Though perhaps it could just be kexec_elf_check_arch() for now, as I don't think there are any other consumers of it. -- Horms H: http://www.vergenet.net/~horms/ W: http://www.valinux.co.jp/en/