diff -r bf5e3af08378 -r 1dbb0770f0b1 src/mem/ruby/system/RubyPort.hh
--- a/src/mem/ruby/system/RubyPort.hh	Thu Jan 06 15:29:01 2011 -0800
+++ b/src/mem/ruby/system/RubyPort.hh	Thu Jan 06 15:29:28 2011 -0800
@@ -36,6 +36,7 @@
 #include "mem/physical.hh"
 #include "mem/protocol/RequestStatus.hh"
 #include "mem/ruby/libruby.hh"
+#include "mem/ruby/system/System.hh"
 #include "mem/tport.hh"
 #include "params/RubyPort.hh"
 
@@ -54,6 +55,7 @@
         M5Port(const std::string &_name, RubyPort *_port);
         bool sendTiming(PacketPtr pkt);
         void hitCallback(PacketPtr pkt);
+        unsigned deviceBlockSize() const;
 
       protected:
         virtual bool recvTiming(PacketPtr pkt);
diff -r bf5e3af08378 -r 1dbb0770f0b1 src/mem/ruby/system/RubyPort.cc
--- a/src/mem/ruby/system/RubyPort.cc	Thu Jan 06 15:29:01 2011 -0800
+++ b/src/mem/ruby/system/RubyPort.cc	Thu Jan 06 15:29:28 2011 -0800
@@ -370,3 +370,9 @@
     }
     return false;
 }
+
+unsigned
+RubyPort::M5Port::deviceBlockSize() const
+{
+    return (unsigned) RubySystem::getBlockSizeBytes();
+}