diff -r 13ce69703444 -r 653c0ded0b9f configs/ruby/MI_example.py
--- a/configs/ruby/MI_example.py	Fri Jul 22 16:02:39 2016 +0100
+++ b/configs/ruby/MI_example.py	Fri Jul 22 16:02:51 2016 +0100
@@ -115,7 +115,7 @@
         l1_cntrl.responseToCache = MessageBuffer(ordered = True)
         l1_cntrl.responseToCache.slave = ruby_system.network.master
 
-    phys_mem_size = sum(map(lambda r: r.size(), system.mem_ranges))
+    phys_mem_size = max(map(lambda r: r.end + 1, system.mem_ranges))
     assert(phys_mem_size % options.num_dirs == 0)
     mem_module_size = phys_mem_size / options.num_dirs