From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755176Ab3A2JGz (ORCPT ); Tue, 29 Jan 2013 04:06:55 -0500 Received: from terminus.zytor.com ([198.137.202.10]:51619 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754843Ab3A2JGv (ORCPT ); Tue, 29 Jan 2013 04:06:51 -0500 Date: Tue, 29 Jan 2013 01:06:11 -0800 From: tip-bot for David Woodhouse Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, dwmw2@infradead.org, tglx@linutronix.de, hpa@linux.intel.com, David.Woodhouse@intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, dwmw2@infradead.org, tglx@linutronix.de, hpa@linux.intel.com, David.Woodhouse@intel.com In-Reply-To: <1355966180.18919.102.camel@shinybook.infradead.org> References: <1355966180.18919.102.camel@shinybook.infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86: Enable ARCH_USE_BUILTIN_BSWAP Git-Commit-ID: 83a57a4de1a222c351667ef9a0fedaac1295e85b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Tue, 29 Jan 2013 01:06:16 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 83a57a4de1a222c351667ef9a0fedaac1295e85b Gitweb: http://git.kernel.org/tip/83a57a4de1a222c351667ef9a0fedaac1295e85b Author: David Woodhouse AuthorDate: Thu, 20 Dec 2012 01:16:20 +0000 Committer: H. Peter Anvin CommitDate: Mon, 28 Jan 2013 08:48:57 -0800 x86: Enable ARCH_USE_BUILTIN_BSWAP With -mmovbe enabled (implicit with -march=atom), this allows the compiler to use the movbe instruction. This doesn't have a significant effect on code size (unlike on PowerPC), because the movbe instruction actually takes as many bytes to encode as a simple mov and a bswap. But for Atom in particular I believe it should give a performance win over the mov+bswap alternative. That was kind of why movbe was invented in the first place, after all... I've done basic functionality testing with IPv6 and Legacy IP, but no performance testing. The EFI firmware on my test box unfortunately no longer starts up. Signed-off-by: David Woodhouse Link: http://lkml.kernel.org/r/1355966180.18919.102.camel@shinybook.infradead.org Signed-off-by: H. Peter Anvin --- arch/x86/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 79795af..3e941aa 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -114,6 +114,7 @@ config X86 select MODULES_USE_ELF_RELA if X86_64 select CLONE_BACKWARDS if X86_32 select GENERIC_SIGALTSTACK + select ARCH_USE_BUILTIN_BSWAP config INSTRUCTION_DECODER def_bool y