sim: Move CPU-specific methods from SimObject to the BaseCPU class

2 files changed, 35 insertions, 5 deletions

diff --git a/src/cpu/BaseCPU.py b/src/cpu/BaseCPU.py
index c27fd1c27..6e5f6ff1a 100644
--- a/src/cpu/BaseCPU.py
+++ b/src/cpu/BaseCPU.py
@@ -77,6 +77,22 @@ class BaseCPU(MemObject):
     type = 'BaseCPU'
     abstract = True
 
+    @classmethod
+    def export_method_cxx_predecls(cls, code):
+        code('#include "cpu/base.hh"')
+
+
+    @classmethod
+    def export_methods(cls, code):
+        code('''
+    void switchOut();
+    void takeOverFrom(BaseCPU *cpu);
+''')
+
+    def takeOverFrom(self, old_cpu):
+        self._ccObject.takeOverFrom(old_cpu._ccObject)
+
+
     system = Param.System(Parent.any, "system object")
     cpu_id = Param.Int(-1, "CPU identifier")
     numThreads = Param.Unsigned(1, "number of HW thread contexts")
diff --git a/src/cpu/base.hh b/src/cpu/base.hh
index 82864ae7b..0c1d19856 100644
--- a/src/cpu/base.hh
+++ b/src/cpu/base.hh
@@ -278,13 +278,27 @@ class BaseCPU : public MemObject
 
     void registerThreadContexts();
 
-    /// Prepare for another CPU to take over execution.  When it is
-    /// is ready (drained pipe) it signals the sampler.
+    /**
+     * Prepare for another CPU to take over execution.
+     *
+     * When this method exits, all internal state should have been
+     * flushed. After the method returns, the simulator calls
+     * takeOverFrom() on the new CPU with this CPU as its parameter.
+     */
     virtual void switchOut();
 
-    /// Take over execution from the given CPU.  Used for warm-up and
-    /// sampling.
-    virtual void takeOverFrom(BaseCPU *);
+    /**
+     * Load the state of a CPU from the previous CPU object, invoked
+     * on all new CPUs that are about to be switched in.
+     *
+     * A CPU model implementing this method is expected to initialize
+     * its state from the old CPU and connect its memory (unless they
+     * are already connected) to the memories connected to the old
+     * CPU.
+     *
+     * @param cpu CPU to initialize read state from.
+     */
+    virtual void takeOverFrom(BaseCPU *cpu);
 
     /**
      *  Number of threads we're actually simulating (<= SMT_MAX_THREADS).