Add execution trace object to Root.

python/m5/objects/Root.py:
    Add execution trace object.

--HG--
extra : convert_revision : 1d1ba18779fd4d0b5af921c5f34b7a2bfb4b75d9
diff --git a/python/m5/objects/Root.py b/python/m5/objects/Root.py
index df8fc4b..23b13fc 100644
--- a/python/m5/objects/Root.py
+++ b/python/m5/objects/Root.py
@@ -3,6 +3,7 @@
 from Serialize import Serialize
 from Statistics import Statistics
 from Trace import Trace
+from ExeTrace import ExecutionTrace
 
 class Root(SimObject):
     type = 'Root'
@@ -20,4 +21,5 @@
     hier = HierParams(do_data = False, do_events = True)
     stats = Statistics()
     trace = Trace()
+    exetrace = ExecutionTrace()
     serialize = Serialize()