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-rw-r--r--arch/sparc/include/asm/system_64.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/sparc/include/asm/system_64.h b/arch/sparc/include/asm/system_64.h
index 25e848f0cad7..d47a98e66972 100644
--- a/arch/sparc/include/asm/system_64.h
+++ b/arch/sparc/include/asm/system_64.h
@@ -63,6 +63,10 @@ do {	__asm__ __volatile__("ba,pt	%%xcc, 1f\n\t" \
 			     : : : "memory"); \
 } while (0)
 
+/* The kernel always executes in TSO memory model these days,
+ * and furthermore most sparc64 chips implement more stringent
+ * memory ordering than required by the specifications.
+ */
 #define mb()	membar_safe("#StoreLoad")
 #define rmb()	__asm__ __volatile__("":::"memory")
 #define wmb()	__asm__ __volatile__("":::"memory")