From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from [2002:a646:1c45::1] (helo=ebiederm.dsl.xmission.com) by canuck.infradead.org with esmtps (Exim 4.63 #1 (Red Hat Linux)) id 1Hijrj-0005zC-C5 for kexec@lists.infradead.org; Tue, 01 May 2007 00:21:30 -0400 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH 1/2] x86_64: Reflect the relocatability of the kernel in the ELF header. References: <200704301717.08230.ak@suse.de> <20070501035539.GA15472@in.ibm.com> Date: Mon, 30 Apr 2007 22:20:53 -0600 In-Reply-To: <20070501035539.GA15472@in.ibm.com> (Vivek Goyal's message of "Tue, 1 May 2007 09:25:39 +0530") Message-ID: MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org+dwmw2=infradead.org@lists.infradead.org To: vgoyal@in.ibm.com Cc: linux-kernel@vger.kernel.org, Kexec Mailing List , Andi Kleen , Jurriaan , Helge Hafting , Horms , Andrew Morton Vivek Goyal writes: > On Mon, Apr 30, 2007 at 05:17:07PM +0200, Andi Kleen wrote: >> On Monday 30 April 2007 17:12:39 Eric W. Biederman wrote: >> > >> > Currently because vmlinux does not reflect that the kernel is relocatable >> > we still have to support CONFIG_PHYSICAL_START. So this patch adds a small >> > c program to do what we cannot do with a linker script set the elf header >> > type to ET_DYN. >> > >> > Since last time I have fixed the type to be in my code ET_DYN (oops), >> > and verified this works with kexec. I realized while testing that we >> > don't have anyway of identifying a kernel vmlinux as linux so we >> > probably want to add an ELF note but that will be another patch. >> >> The patch is ok for me, but does it pass Vivek's usual testing? > > I am facing one issue with this patch. gdb can not analyze the > resulting kernel core file. Looks like gdb treats vmlinux differently if > ELF header type is "ET_DYN". It reads the symbol values incorrectly. Weird. > For example, symbol value of "panic_timeout" is 0xffffffff808a1fa8 but > gdb somehow things that it is 0xffffffff008aaebf. Looks like it is > performing some relocation. > > I am using GNU gdb Red Hat Linux (6.5-5.fc6rh). Does it take a kernel core file to reproduce this problem? Or can you just open up gdb on a vmlinux and look at the symbol address? At least without a core file it is working on with gdb 6.4. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423641AbXEAEVk (ORCPT ); Tue, 1 May 2007 00:21:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423642AbXEAEVk (ORCPT ); Tue, 1 May 2007 00:21:40 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:40914 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423641AbXEAEVj (ORCPT ); Tue, 1 May 2007 00:21:39 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: vgoyal@in.ibm.com Cc: Andi Kleen , Kexec Mailing List , linux-kernel@vger.kernel.org, Jurriaan , Helge Hafting , Horms , Andrew Morton Subject: Re: [PATCH 1/2] x86_64: Reflect the relocatability of the kernel in the ELF header. References: <200704301717.08230.ak@suse.de> <20070501035539.GA15472@in.ibm.com> Date: Mon, 30 Apr 2007 22:20:53 -0600 In-Reply-To: <20070501035539.GA15472@in.ibm.com> (Vivek Goyal's message of "Tue, 1 May 2007 09:25:39 +0530") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) 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 Vivek Goyal writes: > On Mon, Apr 30, 2007 at 05:17:07PM +0200, Andi Kleen wrote: >> On Monday 30 April 2007 17:12:39 Eric W. Biederman wrote: >> > >> > Currently because vmlinux does not reflect that the kernel is relocatable >> > we still have to support CONFIG_PHYSICAL_START. So this patch adds a small >> > c program to do what we cannot do with a linker script set the elf header >> > type to ET_DYN. >> > >> > Since last time I have fixed the type to be in my code ET_DYN (oops), >> > and verified this works with kexec. I realized while testing that we >> > don't have anyway of identifying a kernel vmlinux as linux so we >> > probably want to add an ELF note but that will be another patch. >> >> The patch is ok for me, but does it pass Vivek's usual testing? > > I am facing one issue with this patch. gdb can not analyze the > resulting kernel core file. Looks like gdb treats vmlinux differently if > ELF header type is "ET_DYN". It reads the symbol values incorrectly. Weird. > For example, symbol value of "panic_timeout" is 0xffffffff808a1fa8 but > gdb somehow things that it is 0xffffffff008aaebf. Looks like it is > performing some relocation. > > I am using GNU gdb Red Hat Linux (6.5-5.fc6rh). Does it take a kernel core file to reproduce this problem? Or can you just open up gdb on a vmlinux and look at the symbol address? At least without a core file it is working on with gdb 6.4. Eric