Commit-ID: 83a57a4de1a222c351667ef9a0fedaac1295e85b Gitweb: http://git.kernel.org/tip/83a57a4de1a222c351667ef9a0fedaac1295e85b Author: David Woodhouse <dwmw2@xxxxxxxxxxxxx> AuthorDate: Thu, 20 Dec 2012 01:16:20 +0000 Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> 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 <David.Woodhouse@xxxxxxxxx> Link: http://lkml.kernel.org/r/1355966180.18919.102.camel@xxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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