diff -r 7e82d2b0a20d xen/arch/x86/debug.c
--- a/xen/arch/x86/debug.c
+++ b/xen/arch/x86/debug.c
@@ -34,12 +34,15 @@
 typedef unsigned char dbgbyte_t;
 
 
-#if XEN_SUBVERSION >= 3             /* xen 3.x.x */
+#if XEN_VERSION >= 3             /* xen 3.x.x */
 static noinline int
 dbg_rw_hvm_mem(dbgva_t addr, dbgbyte_t *buf, int len, struct domain *dp,
                int toaddr)
 {
-	return len;
+        if ( toaddr ) 
+                return hvm_copy_to_guest_virt(addr, buf, len) == HVMCOPY_okay;
+        else 
+                return hvm_copy_from_guest_virt(buf, addr, len) == HVMCOPY_okay;         
 }
 
 #else
@@ -82,7 +85,7 @@
     	return len;
 }
 
-#endif /* XEN_SUBVERSION >= 3 */
+#endif /* XEN_VERSION >= 3 */
 
 
 /*
diff -r 7e82d2b0a20d xen/kdb/kdb_cmds.c
--- a/xen/kdb/kdb_cmds.c
+++ b/xen/kdb/kdb_cmds.c
@@ -658,7 +658,7 @@
 	return KDB_CPU_MAIN_KDB;
 }
 
-#if XEN_SUBVERSION >= 3             /* xen 3.x.x */
+#if XEN_VERSION >= 3             /* xen 3.x.x */
 struct  Xgt_desc_struct {
         unsigned short size;
         unsigned long address __attribute__((packed));
@@ -1496,7 +1496,7 @@
 kdb_cpu_cmd_t
 kdb_cmdf_reboot(int argc, const char **argv, struct cpu_user_regs *regs)
 {
-#if XEN_SUBVERSION >= 3             /* xen 3.x.x */
+#if XEN_VERSION >= 3             /* xen 3.x.x */
 	machine_restart();
 #else
 	machine_restart("");