3 files changed, 50 insertions, 0 deletions
diff --git a/src/sim/root.cc b/src/sim/root.cc
index 2d28499a7..34150083d 100644
--- a/src/sim/root.cc
+++ b/src/sim/root.cc
@@ -32,6 +32,7 @@
  */
 
 #include "base/misc.hh"
+#include "config/the_isa.hh"
 #include "debug/TimeSync.hh"
 #include "sim/full_system.hh"
 #include "sim/root.hh"
@@ -121,9 +122,45 @@ Root::initState()
 void
 Root::loadState(Checkpoint *cp)
 {
+    SimObject::loadState(cp);
     timeSyncEnable(params()->time_sync_enable);
 }
 
+void
+Root::serialize(std::ostream &os)
+{
+    uint64_t cpt_ver = gem5CheckpointVersion;
+    SERIALIZE_SCALAR(cpt_ver);
+    SERIALIZE_SCALAR(FullSystem);
+    std::string isa = THE_ISA_STR;
+    SERIALIZE_SCALAR(isa);
+}
+
+void
+Root::unserialize(Checkpoint *cp, const std::string &section)
+{
+    uint64_t cpt_ver = 0;
+    UNSERIALIZE_OPT_SCALAR(cpt_ver);
+    if (cpt_ver < gem5CheckpointVersion) {
+        warn("**********************************************************\n");
+        warn("!!!! Checkpoint ver %#x is older than current ver %#x !!!!\n",
+                cpt_ver, gem5CheckpointVersion);
+        warn("You might experience some issues when restoring and should run "
+             "the checkpoint upgrader (util/cpt_upgrade.py) on your "
+             "checkpoint\n");
+        warn("**********************************************************\n");
+    } else if (cpt_ver > gem5CheckpointVersion) {
+        warn("**********************************************************\n");
+        warn("!!!! Checkpoint ver %#x is newer than current ver %#x !!!!\n",
+                cpt_ver, gem5CheckpointVersion);
+        warn("Running a new checkpoint with an older version of gem5 is not "
+             "supported. While it might work, you may experience incorrect "
+             "behavior or crashes.\n");
+        warn("**********************************************************\n");
+     }
+}
+
+
 bool FullSystem;
 unsigned int FullSystemInt;
 
diff --git a/src/sim/root.hh b/src/sim/root.hh
index 3c3b3c2f3..6a7b5dc93 100644
--- a/src/sim/root.hh
+++ b/src/sim/root.hh
@@ -111,6 +111,10 @@ class Root : public SimObject
     /** Schedule the timesync event at initState() when not unserializing
      */
     void initState();
+
+    virtual void serialize(std::ostream &os);
+    virtual void unserialize(Checkpoint *cp, const std::string &section);
+
 };
 
 #endif // __SIM_ROOT_HH__
diff --git a/src/sim/serialize.hh b/src/sim/serialize.hh
index bc64e74f8..ae20b40c2 100644
--- a/src/sim/serialize.hh
+++ b/src/sim/serialize.hh
@@ -50,6 +50,15 @@ class Serializable;
 class Checkpoint;
 class SimObject;
 
+/** The current version of the checkpoint format.
+ * This should be incremented by 1 and only 1 for every new version, where a new
+ * version is defined as a checkpoint created before this version wont work on
+ * the current version until the checkpoint format is updated. Adding a new
+ * SimObject shouldn't cause the version number to increase, only changes to
+ * existing objects such as serializing/unserializing more stote, changing sizes
+ * of serialized arrays, etc. */
+static const uint64_t gem5CheckpointVersion = 0x0000000000000001;
+
 template <class T>
 void paramOut(std::ostream &os, const std::string &name, const T &param);