diff -r 52aa238d2f66 -r 3a8e34a03c9e src/mem/external_master.cc
--- a/src/mem/external_master.cc	Mon Jan 09 13:15:10 2017 +0100
+++ b/src/mem/external_master.cc	Mon Jan 09 13:18:20 2017 +0100
@@ -36,6 +36,7 @@
  *
  * Authors: Andrew Bardsley
  *          Curtis Dunham
+ *          Christian Menard
  */
 
 #include <cctype>
@@ -43,6 +44,7 @@
 
 #include "debug/ExternalPort.hh"
 #include "mem/external_master.hh"
+#include "sim/system.hh"
 
 std::map<std::string, ExternalMaster::Handler *>
     ExternalMaster::portHandlers;
@@ -52,7 +54,8 @@
     externalPort(NULL),
     portName(params->name + ".port"),
     portType(params->port_type),
-    portData(params->port_data)
+    portData(params->port_data),
+    masterId(params->system->getMasterId(params->name))
 {}
 
 BaseMasterPort &
diff -r 52aa238d2f66 -r 3a8e34a03c9e src/mem/ExternalMaster.py
--- a/src/mem/ExternalMaster.py	Mon Jan 09 13:15:10 2017 +0100
+++ b/src/mem/ExternalMaster.py	Mon Jan 09 13:18:20 2017 +0100
@@ -35,8 +35,10 @@
 #
 # Authors: Andrew Bardsley
 #          Curtis Dunham
+#          Christian Menard
 
 from m5.params import *
+from m5.proxy import *
 from MemObject import MemObject
 
 class ExternalMaster(MemObject):
@@ -50,3 +52,5 @@
     port_data = Param.String('stub', 'A string to pass to the port'
         ' handler (in a format specific to the handler) to describe how'
         ' the port should be bound/bindable/discoverable')
+
+    system = Param.System(Parent.any, 'System this external port belongs to')
diff -r 52aa238d2f66 -r 3a8e34a03c9e src/mem/external_master.hh
--- a/src/mem/external_master.hh	Mon Jan 09 13:15:10 2017 +0100
+++ b/src/mem/external_master.hh	Mon Jan 09 13:18:20 2017 +0100
@@ -36,6 +36,7 @@
  *
  * Authors: Andrew Bardsley
  *          Curtis Dunham
+ *          Christian Menard
  */
 
 /**
@@ -129,6 +130,8 @@
         Handler *handler);
 
     void init();
+
+    const MasterID masterId;
 };