diff -r 73d094e29299 -r 83cc0c3c50f9 src/mem/ruby/system/RubyPort.cc
--- a/src/mem/ruby/system/RubyPort.cc	Thu Aug 05 21:19:13 2010 -0700
+++ b/src/mem/ruby/system/RubyPort.cc	Thu Aug 05 21:19:31 2010 -0700
@@ -222,6 +222,11 @@
         }
     }
 
+    if (pkt->req->isUncacheable()) {
+        fatal("RubyPort received uncacheable access for address 0x%llx\n",
+              (uint64)pkt->getAddr());
+    }
+
     RubyRequest ruby_request(pkt->getAddr(), pkt->getPtr<uint8_t>(),
                              pkt->getSize(), pc, type,
                              RubyAccessMode_Supervisor, pkt);