[PATCH 1/4] Minor conditionals to enable building Scheduler Simulator on GNU/Linux

[Joel Sherrill]

- rtems/score/threadimpl.h: _Thread_Start_multitasking does return
  on Scheduler Simulator. Initializing RTEMS returns to the command
  interpreter.

- rtems/score/smpimpl.h: _SMP_Start_multitasking_on_secondary_processor()
  is not applicable on the Scheduler Simulator and the no return attribute
  gives a warning.

- rtems/score/assert.h: Scheduler Simulator uses glibc assert.h on GNU/Linux.
  This will likely need to be adjusted more for other host compilers and
  C libraries

- threadrestart.c: Disable assert on Scheduler Simulator. Restarting self
  returns to the command interpreter.
---
 cpukit/score/include/rtems/score/assert.h     |   20 ++++++++++++++++----
 cpukit/score/include/rtems/score/smpimpl.h    |    9 ++++++++-
 cpukit/score/include/rtems/score/threadimpl.h |    7 +++++++
 cpukit/score/src/threadrestart.c              |    9 ++++++++-
 4 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/cpukit/score/include/rtems/score/assert.h b/cpukit/score/include/rtems/score/assert.h
index 41ef1ae..d1971d2 100644
--- a/cpukit/score/include/rtems/score/assert.h
+++ b/cpukit/score/include/rtems/score/assert.h
@@ -28,12 +28,24 @@ extern "C" {
 /**
  * @brief Assertion similar to assert() controlled via RTEMS_DEBUG instead of
  * NDEBUG.
+ *
+ * __ASSERT_FUNC is newlib. __ASSERT_FUNCTION is glibc.
  */
 #if defined( RTEMS_DEBUG )
-  #define _Assert( _e ) \
-    ( ( _e ) ? \
-      ( void ) 0 : \
-        __assert_func( __FILE__, __LINE__, __ASSERT_FUNC, #_e ) )
+  #if defined(__ASSERT_FUNC)
+    #define _Assert( _e ) \
+      ( ( _e ) ? \
+        ( void ) 0 : \
+          __assert_func( __FILE__, __LINE__, __ASSERT_FUNC, #_e ) )
+  #elif defined(__ASSERT_FUNCTION)
+    #define _Assert( _e ) \
+      ( ( _e ) ? \
+        ( void ) 0 : \
+          __assert_fail( #_e, __FILE__, __LINE__, __ASSERT_FUNCTION ) )
+  #else
+     #error "What does assert.h use?"
+  #endif
+   
 #else
   #define _Assert( _e ) ( ( void ) 0 )
 #endif
diff --git a/cpukit/score/include/rtems/score/smpimpl.h b/cpukit/score/include/rtems/score/smpimpl.h
index 70475ba..1ed4a4f 100644
--- a/cpukit/score/include/rtems/score/smpimpl.h
+++ b/cpukit/score/include/rtems/score/smpimpl.h
@@ -105,10 +105,17 @@ static inline void _SMP_Fatal( SMP_Fatal_code code )
  * This function must not be called by the main processor.  The main processor
  * uses _Thread_Start_multitasking() instead.
  *
- * This function does not return to the caller.
+ * In a "real system", this function does not return to the caller.
+ * But on the Scheduler Simulator, this method actually returns since
+ * there are no context switches in that environment.
  */
+#ifdef RTEMS_SCHEDSIM
+void _SMP_Start_multitasking_on_secondary_processor( void );
+#else
 void _SMP_Start_multitasking_on_secondary_processor( void )
   RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
+#endif
+
 
 typedef void ( *SMP_Test_message_handler )( Per_CPU_Control *cpu_self );
 
diff --git a/cpukit/score/include/rtems/score/threadimpl.h b/cpukit/score/include/rtems/score/threadimpl.h
index 2be5cc5..35257df 100644
--- a/cpukit/score/include/rtems/score/threadimpl.h
+++ b/cpukit/score/include/rtems/score/threadimpl.h
@@ -97,8 +97,15 @@ void _Thread_Create_idle(void);
  *  This routine initiates multitasking.  It is invoked only as
  *  part of initialization and its invocation is the last act of
  *  the non-multitasking part of the system initialization.
+ *
+ *  @note On the Scheduler Simulator, this method actually returns.
+ *        There are no true context switches in that environment.
  */
+#ifdef RTEMS_SCHEDSIM
+void _Thread_Start_multitasking( void );
+#else
 void _Thread_Start_multitasking( void ) RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
+#endif
 
 /**
  *  @brief Allocate the requested stack space for the thread.
diff --git a/cpukit/score/src/threadrestart.c b/cpukit/score/src/threadrestart.c
index 5c527d8..7c1f77e 100644
--- a/cpukit/score/src/threadrestart.c
+++ b/cpukit/score/src/threadrestart.c
@@ -189,7 +189,14 @@ void _Thread_Life_action_handler(
 
     _Thread_Enable_dispatch();
 
-    _Assert_Not_reached();
+    /*
+     *  On the Scheduler Simulator, there are real context switches -- only
+     *  the bookkeeping. So the "thread of execution" really does return here.
+     *  We need to return to the invoking environment.
+     */
+    #ifndef RTEMS_SCHEDSIM
+      _Assert_Not_reached();
+    #endif
   } else {
     _Assert( _Thread_Is_life_restarting( previous_life_state ) );
 
-- 
1.7.1