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-rw-r--r--arch/x86/Kconfig.cpu11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 018d68e3184..e09a6b73a1a 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -321,8 +321,17 @@ config X86_XADD
depends on X86_32 && !M386
config X86_PPRO_FENCE
- def_bool y
+ bool "PentiumPro memory ordering errata workaround"
depends on M686 || M586MMX || M586TSC || M586 || M486 || M386 || MGEODEGX1
+ help
+ Old PentiumPro multiprocessor systems had errata that could cause memory
+ operations to violate the x86 ordering standard in rare cases. Enabling this
+ option will attempt to work around some (but not all) occurances of
+ this problem, at the cost of much heavier spinlock and memory barrier
+ operations.
+
+ If unsure, say n here. Even distro kernels should think twice before enabling
+ this: there are few systems, and an unlikely bug.
config X86_F00F_BUG
def_bool y