Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752060AbWHNTc4 (ORCPT ); Mon, 14 Aug 2006 15:32:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752063AbWHNTcz (ORCPT ); Mon, 14 Aug 2006 15:32:55 -0400 Received: from terminus.zytor.com ([192.83.249.54]:58091 "EHLO terminus.zytor.com") by vger.kernel.org with ESMTP id S1752061AbWHNTcy (ORCPT ); Mon, 14 Aug 2006 15:32:54 -0400 Message-ID: <44E0CFD0.3060506@zytor.com> Date: Mon, 14 Aug 2006 12:32:32 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.4 (X11/20060614) MIME-Version: 1.0 To: vgoyal@in.ibm.com CC: "Eric W. Biederman" , Don Zickus , fastboot@osdl.org, Horms , Jan Kratochvil , Magnus Damm , linux-kernel@vger.kernel.org Subject: Re: [Fastboot] [CFT] ELF Relocatable x86 and x86_64 bzImages References: <20060807235727.GM16231@redhat.com> <20060809200642.GD7861@redhat.com> <20060810131323.GB9888@in.ibm.com> <20060810181825.GD14732@in.ibm.com> <20060814165150.GA2519@in.ibm.com> <44E0AD1D.1040408@zytor.com> <20060814181118.GB2519@in.ibm.com> In-Reply-To: <20060814181118.GB2519@in.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2043 Lines: 44 Vivek Goyal wrote: > On Mon, Aug 14, 2006 at 10:04:29AM -0700, H. Peter Anvin wrote: >> Vivek Goyal wrote: >>> On Thu, Aug 10, 2006 at 02:09:58PM -0600, Eric W. Biederman wrote: >>>>> I just reserved memory at non 2MB aligned location 65MB@15MB so that >>>>> kernel is loaded at 16MB and other smaller segments below the compressed >>>>> image, then I can successfully booted into the kdump kernel. >>>> :) >>>> >>>>> So basically kexec on panic path seems to be clean except stomping issue. >>>>> May be bzImage program header should reflect right "MemSize" which >>>>> takes into account extra memory space calculations. >>>> Yes. That sounds like the right thing to do. >>>> >>>> I remember trying to compute a good memsize when I created the bzImage >>>> header but it is completely possible I missed some part of the >>>> calculation or assumed that the kernels .bss section would always be >>>> larger than what I needed for decompression. >>>> >> Could someone please describe the intended semantics of this MemSize >> header, *and* its intended usage? >> > > Now and ELF header(attached to bzImage) is being used to describe > the kernel executable. One program header of PT_LOAD type is being > created. The "p_filesz" field of program header is basically > describing the vmlinux file size and "p_memsz" is giving how > much memory will be consumed by kernel image at load time. > > Ideally "p_memsz" should be "p_memsz" summation of all the program > headers of vmlinux file but I guess in this case we are stretching the > ELF specification a little bit and also taking into the account the > additional memory which will be used by decompressor and decompression > logic by the time execution is transferred to the actual kernel. > What about once the kernel is booted? -hpa - 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/