From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751668AbXCPM0P (ORCPT ); Fri, 16 Mar 2007 08:26:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751732AbXCPM0P (ORCPT ); Fri, 16 Mar 2007 08:26:15 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:34367 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751690AbXCPM0N (ORCPT ); Fri, 16 Mar 2007 08:26:13 -0400 Date: Fri, 16 Mar 2007 17:55:59 +0530 From: Vivek Goyal To: Ian Campbell Cc: Magnus Damm , Horms , fastboot@lists.osdl.org, linux-kernel@vger.kernel.org Subject: Re: [Fastboot] [PATCH 1/1] Allow i386 crash kernels to handle x86_64 dumps Message-ID: <20070316122559.GD5642@in.ibm.com> Reply-To: vgoyal@in.ibm.com References: <20070315234807.GB10861@verge.net.au> <1174030097.28658.37.camel@localhost.localdomain> <1174035001.28658.61.camel@localhost.localdomain> <20070316093542.GB5642@in.ibm.com> <20070316113801.GC5642@in.ibm.com> <1174045255.8591.102.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1174045255.8591.102.camel@localhost.localdomain> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 16, 2007 at 11:40:55AM +0000, Ian Campbell wrote: > On Fri, 2007-03-16 at 17:08 +0530, Vivek Goyal wrote: > > On Fri, Mar 16, 2007 at 07:05:30PM +0900, Magnus Damm wrote: > > > On 3/16/07, Vivek Goyal wrote: > > > >Got a question. When running 32bit dom0 on 64bit hypervisor, which > > > >kexec-tools elf loader will kick in? 32bit or 64bit? Looks like in this > > > >case 64bit one. But shouldn't it be 32bit as 32bit OS is running and we > > > >must be using the kexec-tools binary compiled for 32bit OS? And if 32bit > > > >loader kicks in we will not be passing any acpi parameters. > > > > > > There is no check to see if the hypervisor is 32 or 64 bits present > > > today. So the 32-bit version of kexec-tools will support loading > > > images like any other 32-bit kexec-tools. > > > > > > > If that is the case then in prepared elf headers, machine type should > > be EM_386 or similar and not EM_X86_64 and Ian shouldn't have run into > > the problem at all with vmcore. Am I missing something? > > The PRSTATUS ELF notes are generated by the hypervisor not by the kernel > so they are in 64 bit format in this scenario. The machine type should > reflect this. > But ELF header is created in 32bit OS and pre-loaded. At creating time, 32bit kexec-tools will put machine info as EM_386. Who changes it to EM_X86_64 before vmcore code does a sanity check on it using elf_chcek_arch()? Does hypervisor fiddle around with this field? Thanks Vivek