From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753000Ab3A2BdS (ORCPT ); Mon, 28 Jan 2013 20:33:18 -0500 Received: from co1ehsobe004.messaging.microsoft.com ([216.32.180.187]:59098 "EHLO co1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342Ab3A2BdQ (ORCPT ); Mon, 28 Jan 2013 20:33:16 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: 0 X-BigFish: VS0(zzzz1ee6h1de0h1202h1e76h1d1ah1d2ahzz17326ah8275dh8275bhz2dh2a8h668h839h944hd24he5bhf0ah1220h1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1155h) Date: Mon, 28 Jan 2013 19:30:33 -0600 From: Kim Phillips To: Russell King , Andrew Morton CC: Daniel Santos , Borislav Petkov , David Rientjes , Rusty Russell , David Woodhouse , , Subject: [RFC] arm: use built-in byte swap function Message-ID: <20130128193033.8a0b0a871150c99247f05a95@freescale.com> Organization: Freescale Semiconductor, Inc. X-Mailer: Sylpheed 3.2.0 (GTK+ 2.24.13; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Enable the compiler intrinsic for byte swapping on arch ARM. This allows the compiler to detect and be able to optimize out byte swappings, e.g. in big endian to big endian moves. AFAICT, arm gcc got __builtin_bswap{32,64} support in 4.6, and for the 16-bit version in 4.8. Signed-off-by: Kim Phillips --- akin to: http://comments.gmane.org/gmane.linux.kernel.cross-arch/16016 based on linux-next. Depends on commit "compiler-gcc{3,4}.h: Use GCC_VERSION macro" by Daniel Santos , currently in the akpm branch. RFC because of unfamiliarity with arch ARM, and that at91sam9rl, at91rm9200, and lpd270 (so far, at least) builds fail with: include/uapi/linux/swab.h:60: undefined reference to `__bswapsi2' I'm using eldk-5.2.1/armv7a's arm-linux-gnueabi-gcc (GCC) 4.6.4 20120303 (prerelease) arch/arm/Kconfig | 1 + include/linux/compiler-gcc4.h | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index eda8711..437d11a 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -3,6 +3,7 @@ config ARM default y select ARCH_BINFMT_ELF_RANDOMIZE_PIE select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE + select ARCH_USE_BUILTIN_BSWAP select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_WANT_IPC_PARSE_VERSION select BUILDTIME_EXTABLE_SORT if MMU diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index 68b162d..da5f728 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -67,7 +67,8 @@ #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP -#if GCC_VERSION >= 40400 +#if (!defined(__arm__) && GCC_VERSION >= 40400) || \ + (defined(__arm__) && GCC_VERSION >= 40600) #define __HAVE_BUILTIN_BSWAP32__ #define __HAVE_BUILTIN_BSWAP64__ #endif -- 1.7.9.7