sim: revamp unserialization procedure

Replace direct call to unserialize() on each SimObject with a pair of
calls for better control over initialization in both ckpt and non-ckpt
cases.

If restoring from a checkpoint, loadState(ckpt) is called on each
SimObject.  The default implementation simply calls unserialize() if
there is a corresponding checkpoint section, so we get backward
compatibility for existing objects.  However, objects can override
loadState() to get other behaviors, e.g., doing other programmed
initializations after unserialize(), or complaining if no checkpoint
section is found.  (Note that the default warning for a missing
checkpoint section is now gone.)

If not restoring from a checkpoint, we call the new initState() method
on each SimObject instead.  This provides a hook for state
initializations that are only required when *not* restoring from a
checkpoint.

Given this new framework, do some cleanup of LiveProcess subclasses
and X86System, which were (in some cases) emulating initState()
behavior in startup via a local flag or (in other cases) erroneously
doing initializations in startup() that clobbered state loaded earlier
by unserialize().

4 files changed, 7 insertions, 8 deletions

diff --git a/src/arch/power/linux/process.cc b/src/arch/power/linux/process.cc
index 504d0e334..c2587d5e7 100644
--- a/src/arch/power/linux/process.cc
+++ b/src/arch/power/linux/process.cc
@@ -432,9 +432,9 @@ PowerLinuxProcess::getDesc(int callnum)
 }
 
 void
-PowerLinuxProcess::startup()
+PowerLinuxProcess::initState()
 {
-    PowerLiveProcess::startup();
+    PowerLiveProcess::initState();
 }
 
 PowerISA::IntReg
diff --git a/src/arch/power/linux/process.hh b/src/arch/power/linux/process.hh
index db6759a77..bef7e8dae 100644
--- a/src/arch/power/linux/process.hh
+++ b/src/arch/power/linux/process.hh
@@ -44,7 +44,7 @@ class PowerLinuxProcess : public PowerLiveProcess
 
     virtual SyscallDesc* getDesc(int callnum);
 
-    void startup();
+    void initState();
 
     PowerISA::IntReg getSyscallArg(ThreadContext *tc, int &i);
     void setSyscallArg(ThreadContext *tc, int i, PowerISA::IntReg val);
diff --git a/src/arch/power/process.cc b/src/arch/power/process.cc
index 12b216e50..9fb69b9f8 100644
--- a/src/arch/power/process.cc
+++ b/src/arch/power/process.cc
@@ -63,8 +63,10 @@ PowerLiveProcess::PowerLiveProcess(LiveProcessParams *params,
 }
 
 void
-PowerLiveProcess::startup()
+PowerLiveProcess::initState()
 {
+    Process::initState();
+
     argsInit(MachineBytes, VMPageSize);
 }
 
@@ -83,9 +85,6 @@ PowerLiveProcess::argsInit(int intSize, int pageSize)
     //We want 16 byte alignment
     uint64_t align = 16;
 
-    // Overloaded argsInit so that we can fine-tune for POWER architecture
-    Process::startup();
-
     // load object file into target memory
     objFile->loadSections(initVirtMem);
 
diff --git a/src/arch/power/process.hh b/src/arch/power/process.hh
index ede75f05f..473b7e028 100644
--- a/src/arch/power/process.hh
+++ b/src/arch/power/process.hh
@@ -46,7 +46,7 @@ class PowerLiveProcess : public LiveProcess
   protected:
     PowerLiveProcess(LiveProcessParams * params, ObjectFile *objFile);
 
-    void startup();
+    void initState();
 
   public:
     void argsInit(int intSize, int pageSize);