diff -urpN --exclude-from=/home/davej/.exclude bk-linus/arch/i386/Kconfig linux-2.5/arch/i386/Kconfig
--- bk-linus/arch/i386/Kconfig	2002-11-21 02:09:27.000000000 +0000
+++ linux-2.5/arch/i386/Kconfig	2002-11-21 18:23:48.000000000 +0000
@@ -283,6 +283,22 @@ config X86_OOSTORE
 	depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6
 	default y
 
+config X86_SFENCE
+	bool
+	depends on MPENTIUMIII || MPENTIUM4 || MK7
+	default y
+
+config X86_LFENCE
+	bool
+	depends on MPENTIUM4
+	default y
+
+config X86_MFENCE
+	bool
+	depends on MPENTIUM4
+	default y
+
+
 config HUGETLB_PAGE
 	bool "Huge TLB Page Support"
 	help
diff -urpN --exclude-from=/home/davej/.exclude bk-linus/include/asm-i386/system.h linux-2.5/include/asm-i386/system.h
--- bk-linus/include/asm-i386/system.h	2002-11-21 02:21:53.000000000 +0000
+++ linux-2.5/include/asm-i386/system.h	2002-11-21 18:03:25.000000000 +0000
@@ -281,10 +286,33 @@ static inline unsigned long __cmpxchg(vo
  *
  * Some non intel clones support out of order store. wmb() ceases to be a
  * nop for these.
+ *
+ * Pentium III introduced the SFENCE instruction for serialising all store
+ * operations, Pentium IV further introduced LFENCE and MFENCE for load and
+ * memory barriers respecively.
  */
- 
+
+#ifdef CONFIG_X86_MFENCE
+#define mb()	__asm__ __volatile__ ("mfence": : :"memory")
+#else
 #define mb() 	__asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
+#endif
+
+#ifdef CONFIG_X86_LFENCE
+#define rmb()	__asm__ __volatile__ ("lfence": : :"memory")
+#else
 #define rmb()	mb()
+#endif
+
+#ifdef CONFIG_X86_SFENCE
+#define wmb()	__asm__ __volatile__ ("sfence": : :"memory")
+#else
+#ifdef CONFIG_X86_OOSTORE
+#define wmb() 	__asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
+#else
+#define wmb()	__asm__ __volatile__ ("": : :"memory")
+#endif
+#endif /* CONFIG_X86_SFENCE */
 
 /**
  * read_barrier_depends - Flush all pending reads that subsequents reads
@@ -340,12 +368,6 @@ static inline unsigned long __cmpxchg(vo
 
 #define read_barrier_depends()	do { } while(0)
 
-#ifdef CONFIG_X86_OOSTORE
-#define wmb() 	__asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
-#else
-#define wmb()	__asm__ __volatile__ ("": : :"memory")
-#endif
-
 #ifdef CONFIG_SMP
 #define smp_mb()	mb()
 #define smp_rmb()	rmb()