mem: Ignore clean requests in the abstract memory

Systems with atomic cores and the fastmem option enabled bypass the
whole memory system and access the abstract memory directly. Cache
maintenance operations which would be normally handled before the
point of unification/coherence should be ignored by the abstract
memory.

Change-Id: I696cdd158222e5fd67f670cddbcf2efbbfd5eca4
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5054
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index 13a0873cb..b41c82b0d 100644
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -399,13 +399,12 @@ AbstractMemory::access(PacketPtr pkt)
         bytesRead[pkt->req->masterId()] += pkt->getSize();
         if (pkt->req->isInstFetch())
             bytesInstRead[pkt->req->masterId()] += pkt->getSize();
-    } else if (pkt->isInvalidate()) {
+    } else if (pkt->isInvalidate() || pkt->isClean()) {
+        assert(!pkt->isWrite());
+        // in a fastmem system invalidating and/or cleaning packets
+        // can be seen due to cache maintenance requests
+
         // no need to do anything
-        // this clause is intentionally before the write clause: the only
-        // transaction that is both a write and an invalidate is
-        // WriteInvalidate, and for the sake of consistency, it does not
-        // write to memory.  in a cacheless system, there are no WriteInv's
-        // because the Write -> WriteInvalidate rewrite happens in the cache.
     } else if (pkt->isWrite()) {
         if (writeOK(pkt)) {
             if (pmemAddr) {
@@ -419,7 +418,7 @@ AbstractMemory::access(PacketPtr pkt)
             bytesWritten[pkt->req->masterId()] += pkt->getSize();
         }
     } else {
-        panic("unimplemented");
+        panic("Unexpected packet %s", pkt->print());
     }
 
     if (pkt->needsResponse()) {