mem: Enforce strict use of busFirst- and busLastWordTime

This patch adds a check to ensure that the delay incurred by
the bus is not simply disregarded, but accounted for by someone. At
this point, all the modules do is to zero it out, and no additional
time is spent. This highlights where the bus timing is simply dropped
instead of being paid for.

As a follow up, the locations identified in this patch should add this
additional time to the packets in one way or another. For now it
simply acts as a sanity check and highlights where the delay is simply
ignored.

Since no time is added, all regressions remain the same.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/mem/noncoherent_bus.cc b/src/mem/noncoherent_bus.cc
index 4f6751512..f0955bb8f 100644
--- a/src/mem/noncoherent_bus.cc
+++ b/src/mem/noncoherent_bus.cc
@@ -124,6 +124,9 @@ NoncoherentBus::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
         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)));