diff -r 968832fb20bd -r 9a15d64f7738 src/arch/arm/ArmSystem.py
--- a/src/arch/arm/ArmSystem.py	Tue May 27 11:00:56 2014 -0500
+++ b/src/arch/arm/ArmSystem.py	Fri Aug 22 13:31:12 2014 +0100
@@ -65,7 +65,7 @@
     highest_el_is_64 = Param.Bool(False,
         "True if the register width of the highest implemented exception level "
         "is 64 bits (ARMv8)")
-    reset_addr_64 = Param.UInt64(0x0,
+    reset_addr_64 = Param.Addr(0x0,
         "Reset address if the highest implemented exception level is 64 bits "
         "(ARMv8)")
     phys_addr_range_64 = Param.UInt8(40,
diff -r 968832fb20bd -r 9a15d64f7738 src/python/m5/params.py
--- a/src/python/m5/params.py	Tue May 27 11:00:56 2014 -0500
+++ b/src/python/m5/params.py	Fri Aug 22 13:31:12 2014 +0100
@@ -626,9 +626,17 @@
             self.value = value.value
         else:
             try:
+                # Often addresses are referred to with sizes. Ex: A device
+                # base address is at "512MB".  Use toMemorySize() to convert
+                # these into addresses. If the address is not specified with a
+                # "size", an exception will occur and numeric translation will
+                # proceed below.
                 self.value = convert.toMemorySize(value)
-            except TypeError:
-                self.value = long(value)
+            except (TypeError, ValueError):
+                # Convert number to string and use long() to do automatic
+                # base conversion (requires base=0 for auto-conversion)
+                self.value = long(str(value), base=0)
+
         self._check()
     def __add__(self, other):
         if isinstance(other, Addr):