From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753384Ab1IVLnZ (ORCPT ); Thu, 22 Sep 2011 07:43:25 -0400 Received: from mail-ey0-f174.google.com ([209.85.215.174]:58808 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270Ab1IVLnH (ORCPT ); Thu, 22 Sep 2011 07:43:07 -0400 Message-ID: <4E7B1F46.9020706@gmail.com> Date: Thu, 22 Sep 2011 13:43:02 +0200 From: Maarten Lankhorst User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0.2) Gecko/20110906 Thunderbird/6.0.2 MIME-Version: 1.0 To: Matt Fleming CC: linux-kernel@vger.kernel.org, x86@kernel.org, Andi Kleen , Matt Fleming , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Mike Waychison , Matthew Garrett Subject: Re: [PATCH v3 10/10] x86, efi: EFI boot stub support References: <1315838094-2307-11-git-send-email-matt@console-pimps.org> <1316607036-9235-1-git-send-email-matt@console-pimps.org> In-Reply-To: <1316607036-9235-1-git-send-email-matt@console-pimps.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, On 09/21/2011 02:10 PM, Matt Fleming wrote: > From: Matt Fleming > > There is currently a large divide between kernel development and the > development of EFI boot loaders. The idea behind this patch is to give > the kernel developers full control over the EFI boot process. As > H. Peter Anvin put it, > > "The 'kernel carries its own stub' approach been very successful in > dealing with BIOS, and would make a lot of sense to me for EFI as > well." > > This patch introduces an EFI boot stub that allows an x86 bzImage to > be loaded and executed by EFI firmware. The bzImage appears to the > firmware as an EFI application. Luckily there are enough free bits > within the bzImage header so that it can masquerade as an EFI > application, thereby coercing the EFI firmware into loading it and > jumping to its entry point. The beauty of this masquerading approach > is that both BIOS and EFI boot loaders can still load and run the same > bzImage, thereby allowing a single kernel image to work in any boot > environment. > > The EFI boot stub supports multiple initrds, but they must exist on > the same partition as the bzImage. Command-line arguments for the > kernel can be appended after the bzImage name when run from the EFI > shell, e.g. > > Shell> bzImage console=ttyS0 root=/dev/sdb initrd=initrd.img > > Cc: H. Peter Anvin > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: Mike Waychison > Cc: Matthew Garrett > Signed-off-by: Matt Fleming > --- > > v3: > - Fix following warnings when compiling CONFIG_EFI_STUB=n > > arch/x86/boot/tools/build.c: In function ‘main’: > arch/x86/boot/tools/build.c:138:24: warning: unused variable ‘pe_header’ > arch/x86/boot/tools/build.c:138:15: warning: unused variable ‘file_sz’ > > - As reported by Matthew Garrett, some Apple machines have GOPs that > don't have hardware attached. We need to weed these out by > searching for ones that handle the PCIIO protocol. > > - Don't allocate memory if no initrds are on cmdline > - Don't trust image->load_options_size > > - Maarten Lankhorst suggested: > - Don't strip first argument when booted from efibootmgr > - Don't allocate too much memory for cmdline > - Don't update cmdline_size, the kernel considers it read-only > - Don't accept '\n' for initrd names Even if load_options_size is not always completely reliable, could you at least prevent reading more than image->load_options_size? Code below doesn't seem to do that currently.. Thanks, Maarten