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>

diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index 13a0873cb3b64e7f024be284ed46a4406509bb60..b41c82b0de037daf1754943fc8d0068ad5530eac 100644 (file)
--- 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()) {