diff -r 351034b23e3b -r 523d0e0d4f36 src/dev/io_device.cc
--- a/src/dev/io_device.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/dev/io_device.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -54,6 +54,9 @@
 Tick
 PioPort::recvAtomic(PacketPtr pkt)
 {
+    // @todo: We need to pay for this and not just zero it out
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
     return pkt->isRead() ? device->read(pkt) : device->write(pkt);
 }
 
diff -r 351034b23e3b -r 523d0e0d4f36 src/dev/pcidev.cc
--- a/src/dev/pcidev.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/dev/pcidev.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -67,6 +67,8 @@
 {
     assert(pkt->getAddr() >= configAddr &&
            pkt->getAddr() < configAddr + PCI_CONFIG_SIZE);
+    // @todo someone should pay for this
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
     return pkt->isRead() ? device->readConfig(pkt) : device->writeConfig(pkt);
 }
 
diff -r 351034b23e3b -r 523d0e0d4f36 src/dev/x86/intdev.hh
--- a/src/dev/x86/intdev.hh	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/dev/x86/intdev.hh	Thu Feb 14 09:58:31 2013 +0000
@@ -81,6 +81,8 @@
 
         Tick recvMessage(PacketPtr pkt)
         {
+            // @todo someone should pay for this
+            pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
             return device->recvMessage(pkt);
         }
     };
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/bridge.cc
--- a/src/mem/bridge.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/bridge.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -141,6 +141,9 @@
 
     DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size());
 
+    // @todo: We need to pay for this and not just zero it out
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
     slavePort.schedTimingResp(pkt, bridge.clockEdge(delay));
 
     return true;
@@ -171,6 +174,10 @@
             assert(outstandingResponses != respQueueLimit);
             ++outstandingResponses;
             retryReq = false;
+
+            // @todo: We need to pay for this and not just zero it out
+            pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
             masterPort.schedTimingReq(pkt, bridge.clockEdge(delay));
         }
     }
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/bus.cc
--- a/src/mem/bus.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/bus.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -140,6 +140,13 @@
     // determine how many cycles are needed to send the data
     unsigned dataCycles = pkt->hasData() ? divCeil(pkt->getSize(), width) : 0;
 
+    // before setting the bus delay fields of the packet, ensure that
+    // the delay from any previous bus has been accounted for
+    if (pkt->busFirstWordDelay != 0 || pkt->busLastWordDelay != 0)
+        panic("Packet %s already has bus delay (%d, %d) that should be "
+              "accounted for.\n", pkt->cmdString(), pkt->busFirstWordDelay,
+              pkt->busLastWordDelay);
+
     // The first word will be delivered on the cycle after the header.
     pkt->busFirstWordDelay = (headerCycles + 1) * clockPeriod() + offset;
 
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/cache/cache_impl.hh
--- a/src/mem/cache/cache_impl.hh	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/cache/cache_impl.hh	Thu Feb 14 09:58:31 2013 +0000
@@ -391,6 +391,8 @@
 
     rec->restore(pkt, this);
     delete rec;
+    // @todo someone should pay for this
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
     memSidePort->schedTimingSnoopResp(pkt, time);
 }
 
@@ -423,6 +425,9 @@
         // supplier had exclusive copy to begin with.
         if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) {
             Packet *snoopPkt = new Packet(pkt, true);  // clear flags
+            // also reset the bus time that the original packet has
+            // not yet paid for
+            snoopPkt->busFirstWordDelay = snoopPkt->busLastWordDelay = 0;
             snoopPkt->setExpressSnoop();
             snoopPkt->assertMemInhibit();
             memSidePort->sendTimingReq(snoopPkt);
@@ -441,6 +446,9 @@
     if (pkt->req->isUncacheable()) {
         uncacheableFlush(pkt);
 
+        // @todo: someone should pay for this
+        pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
         // writes go in write buffer, reads use MSHR
         if (pkt->isWrite() && !pkt->isRead()) {
             allocateWriteBuffer(pkt, time, true);
@@ -493,6 +501,8 @@
 
         if (needsResponse) {
             pkt->makeTimingResponse();
+            // @todo: Make someone pay for this
+            pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
             cpuSidePort->schedTimingResp(pkt, clockEdge(lat));
         } else {
             /// @todo nominally we should just delete the packet here,
@@ -503,6 +513,9 @@
     } else {
         // miss
 
+        // @todo: Make someone pay for this
+        pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
         Addr blk_addr = blockAlign(pkt->getAddr());
         MSHR *mshr = mshrQueue.findMatch(blk_addr);
 
@@ -935,6 +948,8 @@
                 // isInvalidate() set otherwise.
                 target->pkt->cmd = MemCmd::ReadRespWithInvalidate;
             }
+            // reset the bus additional time as it is now accounted for
+            target->pkt->busFirstWordDelay = target->pkt->busLastWordDelay = 0;
             cpuSidePort->schedTimingResp(target->pkt, completion_time);
             break;
 
@@ -1239,6 +1254,8 @@
     assert(req_pkt->isInvalidate() || pkt->sharedAsserted());
     pkt->allocate();
     pkt->makeTimingResponse();
+    // @todo Make someone pay for this
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
     if (pkt->isRead()) {
         pkt->setDataFromBlock(blk_data, blkSize);
     }
@@ -1282,6 +1299,9 @@
             Packet snoopPkt(pkt, true);  // clear flags
             snoopPkt.setExpressSnoop();
             snoopPkt.senderState = new ForwardResponseRecord(pkt, this);
+            // the snoop packet does not need to wait any additional
+            // time
+            snoopPkt.busFirstWordDelay = snoopPkt.busLastWordDelay = 0;
             cpuSidePort->sendTimingSnoopReq(&snoopPkt);
             if (snoopPkt.memInhibitAsserted()) {
                 // cache-to-cache response from some upper cache
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/coherent_bus.cc
--- a/src/mem/coherent_bus.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/coherent_bus.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -177,6 +177,9 @@
             if (add_outstanding)
                 outstandingReq.erase(pkt->req);
 
+            // undo the calculation so we can check for 0 again
+            pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
             DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x RETRY\n",
                     src_port->name(), pkt->cmdString(), pkt->getAddr());
 
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/noncoherent_bus.cc
--- a/src/mem/noncoherent_bus.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/noncoherent_bus.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -124,6 +124,9 @@
         DPRINTF(NoncoherentBus, "recvTimingReq: src %s %s 0x%x RETRY\n",
                 src_port->name(), pkt->cmdString(), pkt->getAddr());
 
+        // undo the calculation so we can check for 0 again
+        pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
         // occupy until the header is sent
         reqLayer.failedTiming(src_port, clockEdge(Cycles(headerCycles)));
 
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/simple_dram.cc
--- a/src/mem/simple_dram.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/simple_dram.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -741,6 +741,9 @@
         // access already turned the packet into a response
         assert(pkt->isResponse());
 
+        // @todo someone should pay for this
+        pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
         // queue the packet in the response queue to be sent out the
         // next tick
         port.schedTimingResp(pkt, curTick() + 1);
diff -r 351034b23e3b -r 523d0e0d4f36 src/mem/simple_mem.cc
--- a/src/mem/simple_mem.cc	Thu Feb 14 09:58:16 2013 +0000
+++ b/src/mem/simple_mem.cc	Thu Feb 14 09:58:31 2013 +0000
@@ -121,6 +121,9 @@
         return false;
     }
 
+    // @todo someone should pay for this
+    pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
+
     // update the release time according to the bandwidth limit, and
     // do so with respect to the time it takes to finish this request
     // rather than long term as it is the short term data rate that is