diff --git a/src/mem/SConscript b/src/mem/SConscript
index d391fbd5c..c181c88c6 100644
--- a/src/mem/SConscript
+++ b/src/mem/SConscript
@@ -47,6 +47,7 @@ Source('packet.cc')
 Source('physical.cc')
 Source('port.cc')
 Source('tport.cc')
+Source('mport.cc')
 
 if env['FULL_SYSTEM']:
     Source('vport.cc')
diff --git a/src/mem/mport.cc b/src/mem/mport.cc
new file mode 100644
index 000000000..72bcfc7fd
--- /dev/null
+++ b/src/mem/mport.cc
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2008 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#include "mem/mport.hh"
+
+Tick
+MessagePort::recvAtomic(PacketPtr pkt)
+{
+    if (pkt->cmd == MemCmd::MessageReq) {
+        // We received a message.
+        return recvMessage(pkt);
+    } else if (pkt->cmd == MemCmd::MessageResp) {
+        return recvResponse(pkt);
+    } else if (pkt->wasNacked()) {
+        return recvNack(pkt);
+    } else if (pkt->isError()) {
+        panic("Packet is error.\n");
+    } else {
+        panic("Unexpected memory command %s.\n", pkt->cmd.toString());
+    }
+}
+
+void
+MessagePort::sendMessageTiming(PacketPtr pkt, Tick latency)
+{
+    schedSendTiming(pkt, curTick + latency);
+}
+
+Tick
+MessagePort::sendMessageAtomic(PacketPtr pkt)
+{
+    return sendAtomic(pkt);
+}
diff --git a/src/mem/mport.hh b/src/mem/mport.hh
new file mode 100644
index 000000000..5975f89f0
--- /dev/null
+++ b/src/mem/mport.hh
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2008 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#ifndef __MEM_MPORT_HH__
+#define __MEM_MPORT_HH__
+
+#include "mem/tport.hh"
+
+/*
+ * This file defines a port class which is used for sending and receiving
+ * messages. These messages are atomic units which don't interact and
+ * should be smaller than a cache block. This class is based on 
+ * the underpinnings of SimpleTimingPort, but it tweaks some of the external
+ * functions.
+ */
+
+class MessagePort : public SimpleTimingPort
+{
+  public:
+    MessagePort(std::string pname, MemObject *_owner = NULL) :
+        SimpleTimingPort(pname, _owner)
+    {}
+
+    virtual ~MessagePort()
+    {}
+
+    void
+    recvFunctional(PacketPtr pkt)
+    {
+        recvAtomic(pkt);
+    }
+
+    Tick recvAtomic(PacketPtr pkt);
+
+    virtual Tick recvMessage(PacketPtr pkt) = 0;
+
+    // Accept and ignore responses.
+    virtual Tick recvResponse(PacketPtr pkt)
+    {
+        return 0;
+    }
+
+    // Since by default we're assuming everything we send is accepted, panic.
+    virtual Tick recvNack(PacketPtr pkt)
+    {
+        panic("Unhandled message nack.\n");
+    }
+
+    void sendMessageTiming(PacketPtr pkt, Tick latency);
+    Tick sendMessageAtomic(PacketPtr pkt);
+};
+
+#endif
diff --git a/src/mem/packet.cc b/src/mem/packet.cc
index 35fd44e5b..f27bd9dbf 100644
--- a/src/mem/packet.cc
+++ b/src/mem/packet.cc
@@ -118,6 +118,11 @@ MemCmd::commandInfo[] =
     /* SwapResp -- for Swap ldstub type operations */
     { SET5(IsRead, IsWrite, NeedsExclusive, IsResponse, HasData),
             InvalidCmd, "SwapResp" },
+    /* IntReq -- for interrupts */
+    { SET4(IsWrite, IsRequest, NeedsResponse, HasData),
+        MessageReq, "MessageReq" },
+    /* IntResp -- for interrupts */
+    { SET2(IsWrite, IsResponse), MessageResp, "MessageResp" },
     /* NetworkNackError  -- nacked at network layer (not by protocol) */
     { SET2(IsResponse, IsError), InvalidCmd, "NetworkNackError" },
     /* InvalidDestError  -- packet dest field invalid */
diff --git a/src/mem/packet.hh b/src/mem/packet.hh
index 36aff5b42..1227cec89 100644
--- a/src/mem/packet.hh
+++ b/src/mem/packet.hh
@@ -85,6 +85,8 @@ class MemCmd
         StoreCondResp,
         SwapReq,
         SwapResp,
+        MessageReq,
+        MessageResp,
         // Error responses
         // @TODO these should be classified as responses rather than
         // requests; coding them as requests initially for backwards
diff --git a/src/mem/tport.cc b/src/mem/tport.cc
index 254487af8..f8850df6c 100644
--- a/src/mem/tport.cc
+++ b/src/mem/tport.cc
@@ -65,7 +65,7 @@ SimpleTimingPort::recvTiming(PacketPtr pkt)
     // code to hanldle nacks here, but I'm pretty sure it didn't work
     // correctly with the drain code, so that would need to be fixed
     // if we ever added it back.
-    assert(pkt->isRequest());
+    //assert(pkt->isRequest());
 
     if (pkt->memInhibitAsserted()) {
         // snooper will supply based on copy of packet