Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934607AbaFSUcT (ORCPT ); Thu, 19 Jun 2014 16:32:19 -0400 Received: from mail-qg0-f48.google.com ([209.85.192.48]:35142 "EHLO mail-qg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932071AbaFSUcP (ORCPT ); Thu, 19 Jun 2014 16:32:15 -0400 Date: Thu, 19 Jun 2014 16:32:12 -0400 (EDT) From: Nicolas Pitre To: Kevin Hilman cc: Stephen Boyd , Taras Kondratiuk , Thomas Petazzoni , Russell King , Jason Cooper , Victor Kamensky , LKML , Ben Dooks , Olof Johansson , Linaro Networking , linux-arm-kernel Subject: Re: [PATCH] ARM: zImage: ensure header in LE format for BE8 kernels In-Reply-To: <7hk38cycuh.fsf@paris.lan> Message-ID: References: <1397147232-28516-1-git-send-email-taras.kondratiuk@linaro.org> <53A1D701.8060404@codeaurora.org> <53A1D8FE.6030404@codeaurora.org> <7hk38cycuh.fsf@paris.lan> User-Agent: Alpine 2.11 (LFD 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Jun 2014, Kevin Hilman wrote: > I think this should probably be officialized since we've taken away the > ability for magic-number checking tools (like 'file') to distinguish > between big- and little-endian zImages. > > For now, I've updated my tools to check for 'setend be' in ARM and > Thumb2 mode, but if this does get officialized, I'll gladly move over to > it. Would you ACK this patch? ----- >8 ARM: zImage: identify kernel endianness With patch #8067/1 applied, it is no longer possible to determine the endianness of a compiled kernel image. This normally shouldn't matter to the boot environment, except for those cases where the selection of a ramdisk or root filesystem with a matching endianness has to be automated. Let's add a flag to the zImage header indicating the actual endianness. Four bytes from offset 0x30 can be interpreted as follows: 04 03 02 01 big endian kernel 01 02 03 04 little endian kernel Anything else should be interpreted as "unknown", in which case it is most likely that patch #8067/1 was not applied either and the zImage magic number at offset 0x24 could be used instead to determine endianness. No zImage before this patch ever produced 0x01020304 nor 0x04030201 at offset 0x30 so there is no confusion possible. Signed-off-by: Nicolas Pitre diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index c95feab6ce..413fd94b53 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -128,6 +128,7 @@ start: .word _magic_sig @ Magic numbers to help the loader .word _magic_start @ absolute load/run zImage address .word _magic_end @ zImage end address + .word 0x04030201 @ endianness flag THUMB( .thumb ) 1: -- 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/