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authorChristoph Lameter <cl@linux.com>2011-06-01 21:25:47 +0400
committerH. Peter Anvin <hpa@zytor.com>2011-06-25 23:17:32 +0400
commit3824abd1279ef75f791c43a6b1e3162ae0692b42 (patch)
treef8ca989ec654a9f5cffc28eca7acb4e8a5389814 /arch/x86/Kconfig.cpu
parent56299378726d5f2ba8d3c8cbbd13cb280ba45e4f (diff)
downloadlinux-3824abd1279ef75f791c43a6b1e3162ae0692b42.tar.xz
x86: Add support for cmpxchg_double
A simple implementation that only supports the word size and does not have a fallback mode (would require a spinlock). Add 32 and 64 bit support for cmpxchg_double. cmpxchg double uses the cmpxchg8b or cmpxchg16b instruction on x86 processors to compare and swap 2 machine words. This allows lockless algorithms to move more context information through critical sections. Set a flag CONFIG_CMPXCHG_DOUBLE to signal that support for double word cmpxchg detection has been build into the kernel. Note that each subsystem using cmpxchg_double has to implement a fall back mechanism as long as we offer support for processors that do not implement cmpxchg_double. Reviewed-by: H. Peter Anvin <hpa@zytor.com> Cc: Tejun Heo <tj@kernel.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Christoph Lameter <cl@linux.com> Link: http://lkml.kernel.org/r/20110601172614.173427964@linux.com Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/Kconfig.cpu')
-rw-r--r--arch/x86/Kconfig.cpu3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 6a7cfdf8ff69..e3ca7e0d858c 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -312,6 +312,9 @@ config X86_CMPXCHG
config CMPXCHG_LOCAL
def_bool X86_64 || (X86_32 && !M386)
+config CMPXCHG_DOUBLE
+ def_bool y
+
config X86_L1_CACHE_SHIFT
int
default "7" if MPENTIUM4 || MPSC