diff -r 70ef8cbec4fe -r 2d964402b9fc src/python/m5/SimObject.py
--- a/src/python/m5/SimObject.py	Wed May 02 16:08:49 2012 -0400
+++ b/src/python/m5/SimObject.py	Wed May 02 16:09:02 2012 -0400
@@ -1061,42 +1061,105 @@
         self._ccObject.takeOverFrom(old_cpu._ccObject)
 
     # generate output file for 'dot' to display as a pretty graph.
-    def outputDot(self, dot):
+    # need to create all nodes (components) before creating edges (memory channels)
+    def dotCreateNodes(self, callgraph):
         if isRoot(self):
-            label = "{root|"
+            label = "root"
         else:
-            label = "{%s|" % self._name
+            label = self._name
+        full_path = re.sub('\.', '_', self.path())
 
-        if isSimObject(self._base):
-            label +=  '%s|' % self.type
+        # each component is a sub-graph (cluster)
+        cluster = self.dotCreateCluster(full_path, label)
 
+        # create nodes per port
+        for port_name in self._ports.keys():
+            port = self._port_refs.get(port_name, None)
+            if port != None:
+                full_port_name = full_path + "_" + port_name
+                port_node = self.dotCreateNode(full_port_name, port_name)
+                cluster.add_node(port_node)
+
+        # recurse to children
         if self._children:
             for c in self._children:
                 child = self._children[c]
                 if isSimObjectVector(child):
                     for obj in child:
-                        dot.add_edge(pydot.Edge(self.path(), obj.path(), style="bold"))
+                        obj.dotCreateNodes(cluster)
                 else:
-                    dot.add_edge(pydot.Edge(self.path(), child.path(), style="bold"))
+                    child.dotCreateNodes(cluster)
 
-        for param in self._params.keys():
-            value = self._values.get(param)
-            if value != None:
-                ini_str_value = self._values[param].ini_str()
-                label += '%s = %s\\n' % (param, re.sub(':', '-', ini_str_value))
+        callgraph.add_subgraph(cluster)
 
-        label += '}'
+    # create all edges according to memory hierarchy
+    def dotCreateEdges(self, callgraph):
+        for port_name in self._ports.keys():
+            port = self._port_refs.get(port_name, None)
+            if port != None:
+                full_path = re.sub('\.', '_', self.path())
+                full_port_name = full_path + "_" + port_name
+                port_node = self.dotCreateNode(full_port_name, port_name)
+                # create edges
+                if type(port) is m5.params.PortRef:
+                    self.dotAddEdge(callgraph, full_port_name, port)
+                else:
+                    for p in port.elements:
+                        self.dotAddEdge(callgraph, full_port_name, p)
 
-        dot.add_node(pydot.Node(self.path(), shape="Mrecord",label=label))
+        # recurse to children
+        if self._children:
+            for c in self._children:
+                child = self._children[c]
+                if isSimObjectVector(child):
+                    for obj in child:
+                        obj.dotCreateEdges(callgraph)
+                else:
+                    child.dotCreateEdges(callgraph)
 
-        # recursively dump out children
-        for c in self._children:
-            child = self._children[c]
-            if isSimObjectVector(child):
-                for obj in child:
-                    obj.outputDot(dot)
-            else:
-                child.outputDot(dot)
+    def dotAddEdge(self, callgraph, full_port_name, peerPort):
+        if peerPort.role == "MASTER":
+            peer_port_name = re.sub('\.', '_', peerPort.peer.simobj.path() \
+                    + "." + peerPort.peer.name)
+            callgraph.add_edge(pydot.Edge(full_port_name, peer_port_name))
+
+    def dotCreateCluster(self, full_path, label):
+        # if you read this, feel free to modify colors / style
+        return pydot.Cluster( \
+                             full_path, \
+                             shape = "Mrecord", \
+                             label = label, \
+                             style = "\"rounded, filled\"", \
+                             color = "#000000", \
+                             fillcolor = self.dotGenColor(), \
+                             fontname = "Arial", \
+                             fontsize = "14", \
+                             fontcolor = "#000000" \
+                             )
+
+    def dotCreateNode(self, full_path, label):
+        # if you read this, feel free to modify colors / style.
+        # leafs may have a different style => seperate function
+        return pydot.Node( \
+                             full_path, \
+                             shape = "Mrecord", \
+                             label = label, \
+                             style = "\"rounded, filled\"", \
+                             color = "#000000", \
+                             fillcolor = "#808080", \
+                             fontname = "Arial", \
+                             fontsize = "14", \
+                             fontcolor = "#000000" \
+                             )
+    # generate color for nodes
+    # currently a simple grayscale. placeholder for aesthetic programmers.
+    def dotGenColor(self):
+        depth = len(self.path().split('.'))
+        depth = 256 - depth * 16 * 3
+        return self.dotRgbToHtml(depth, depth, depth)
+
+    def dotRgbToHtml(self, r, g, b):
+        return "#%.2x%.2x%.2x" % (r, g, b)
 
 # Function to provide to C++ so it can look up instances based on paths
 def resolveSimObject(name):
diff -r 70ef8cbec4fe -r 2d964402b9fc src/python/m5/simulate.py
--- a/src/python/m5/simulate.py	Wed May 02 16:08:49 2012 -0400
+++ b/src/python/m5/simulate.py	Wed May 02 16:09:02 2012 -0400
@@ -1,3 +1,15 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
 # Copyright (c) 2005 The Regents of The University of Michigan
 # Copyright (c) 2010 Advanced Micro Devices, Inc.
 # All rights reserved.
@@ -122,15 +134,17 @@
 
 def doDot(root):
     from m5 import options
-    dot = pydot.Dot()
-    root.outputDot(dot)
-    dot.orientation = "portrait"
-    dot.size = "8.5,11"
-    dot.ranksep="equally"
-    dot.rank="samerank"
+    callgraph = pydot.Dot(graph_type='digraph')
+    root.dotCreateNodes(callgraph)
+    root.dotCreateEdges(callgraph)
     dot_filename = os.path.join(options.outdir, options.dot_config)
-    dot.write(dot_filename)
-    dot.write_pdf(dot_filename + ".pdf")
+    callgraph.write(dot_filename)
+    try:
+        # dot crashes if the figure is extremely wide.
+        # So avoid terminating simulation unnecessarily
+        callgraph.write_pdf(dot_filename + ".pdf")
+    except:
+        print "warning: failed to generate pdf output from %s" % dot_filename
 
 need_resume = []
 need_startup = True