diff -Nuarp xen-unstable.orig/tools/blktap/blktaplib.h xen-unstable/tools/blktap/blktaplib.h
--- xen-unstable.orig/tools/blktap/blktaplib.h	2005-03-01 22:50:19.499166000 -0500
+++ xen-unstable/tools/blktap/blktaplib.h	2005-03-01 23:07:52.849166000 -0500
@@ -8,24 +8,7 @@
 #ifndef __BLKTAPLIB_H__
 #define __BLKTAPLIB_H__
 
-#include <stdint.h>
-
-typedef uint8_t            u8;
-typedef uint16_t           u16;
-typedef uint32_t           u32;
-typedef uint64_t           u64;
-typedef int8_t             s8;
-typedef int16_t            s16;
-typedef int32_t            s32;
-typedef int64_t            s64;
-                                                                                
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-    
+#include <xc.h>
 #include <sys/user.h>
 #include <xen/xen.h>
 #include <xen/io/blkif.h>
diff -Nuarp xen-unstable.orig/tools/libxc/xc.h xen-unstable/tools/libxc/xc.h
--- xen-unstable.orig/tools/libxc/xc.h	2005-03-01 22:50:19.499166000 -0500
+++ xen-unstable/tools/libxc/xc.h	2005-03-01 23:07:14.069166000 -0500
@@ -25,6 +25,21 @@ typedef int64_t            s64;
 #include <xen/event_channel.h>
 #include <xen/sched_ctl.h>
 
+
+/*\
+ *  DEFINITIONS FOR CPU BARRIERS
+\*/ 
+#if defined(__i386__)
+#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
+#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
+#elif defined(__x86_64__)
+#define mb() __asm__ __volatile__ ( "mfence" : : : "memory" )
+#define rmb() __asm__ __volatile__ ( "lfence" : : : "memory" )
+#define wmb() __asm__ __volatile__ ( "sfence" : : : "memory" )
+#else
+#error "Define barriers"
+#endif
+
 /*\
  *  INITIALIZATION FUNCTIONS
 \*/ 
diff -Nuarp xen-unstable.orig/tools/python/xen/lowlevel/xu/xu.c xen-unstable/tools/python/xen/lowlevel/xu/xu.c
--- xen-unstable.orig/tools/python/xen/lowlevel/xu/xu.c	2005-03-01 22:50:19.519166000 -0500
+++ xen-unstable/tools/python/xen/lowlevel/xu/xu.c	2005-03-01 23:07:14.069166000 -0500
@@ -49,14 +49,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
-
 /* Set the close-on-exec flag on a file descriptor.  Doesn't currently bother
  * to check for errors. */
 /*
diff -Nuarp xen-unstable.orig/tools/xcs/xcs.h xen-unstable/tools/xcs/xcs.h
--- xen-unstable.orig/tools/xcs/xcs.h	2005-03-01 22:50:19.499166000 -0500
+++ xen-unstable/tools/xcs/xcs.h	2005-03-01 23:07:14.069166000 -0500
@@ -39,13 +39,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
 #ifndef timersub /* XOPEN and __BSD don't cooperate well... */
 #define timersub(a, b, result)                                                \
   do {                                                                        \