From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031321Ab3HIWNE (ORCPT ); Fri, 9 Aug 2013 18:13:04 -0400 Received: from swan.laptop.org ([18.85.2.166]:37792 "EHLO swan.laptop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031204Ab3HIWND (ORCPT ); Fri, 9 Aug 2013 18:13:03 -0400 From: Daniel Drake To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org Cc: linux-kernel@vger.kernel.org, pgf@laptop.org, dilinger@queued.net, yinghai@kernel.org Subject: [PATCH RESEND] x86: don't clear olpc_ofw_header when sentinel is detected Message-Id: <20130809221420.618E6FAB03@dev.laptop.org> Date: Fri, 9 Aug 2013 18:14:20 -0400 (EDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org OpenFirmware wasn't quite following the protocol described in boot.txt and the kernel has detected this through use of the sentinel value in boot_params. OFW does zero out almost all of the stuff that it should do, but not the sentinel. This causes the kernel to clear olpc_ofw_header, which breaks x86 OLPC support. OpenFirmware has now been fixed. However, it would be nice if we could maintain Linux compatibility with old firmware versions. To do that, we just have to avoid zeroing out olpc_ofw_header. OFW does not write to any other parts of the header that are being zapped by the sentinel-detection code, and all users of olpc_ofw_header are somewhat protected through checking for the OLPC_OFW_SIG magic value before using it. So this should not cause any problems for anyone. Signed-off-by: Daniel Drake Acked-by: Yinghai Lu --- arch/x86/include/asm/bootparam_utils.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Resending after 4 weeks, and updated commit message to mention that OFW is now fixed for future versions. diff --git a/arch/x86/include/asm/bootparam_utils.h b/arch/x86/include/asm/bootparam_utils.h index 653668d..4a8cb8d 100644 --- a/arch/x86/include/asm/bootparam_utils.h +++ b/arch/x86/include/asm/bootparam_utils.h @@ -35,9 +35,9 @@ static void sanitize_boot_params(struct boot_params *boot_params) */ if (boot_params->sentinel) { /* fields in boot_params are left uninitialized, clear them */ - memset(&boot_params->olpc_ofw_header, 0, + memset(&boot_params->ext_ramdisk_image, 0, (char *)&boot_params->efi_info - - (char *)&boot_params->olpc_ofw_header); + (char *)&boot_params->ext_ramdisk_image); memset(&boot_params->kbd_status, 0, (char *)&boot_params->hdr - (char *)&boot_params->kbd_status); -- 1.8.1.4