cpu: Warn when (un)serializing a traffic generator

When checkpointing a system with a traffic generator, a warning is
produced so that the user is reminded serialization does not keep all
the traffic generator internal state.

Change-Id: I3c49c912c9ff3a4208f55b2da0a88fc694147280
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11831
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/cpu/testers/traffic_gen/base.cc

@@ -124,6 +124,9 @@ BaseTrafficGen::drain()
 void
 BaseTrafficGen::serialize(CheckpointOut &cp) const
 {
+    warn("%s serialization does not keep all traffic generator"
+         " internal state\n", name());
+
     DPRINTF(Checkpoint, "Serializing BaseTrafficGen\n");
 
     // save ticks of the graph event if it is scheduled
@@ -141,6 +144,9 @@ BaseTrafficGen::serialize(CheckpointOut &cp) const
 void
 BaseTrafficGen::unserialize(CheckpointIn &cp)
 {
+    warn("%s serialization does not restore all traffic generator"
+         " internal state\n", name());
+
     // restore scheduled events
     Tick nextEvent;
     UNSERIALIZE_SCALAR(nextEvent);