SMP: Add per-CPU initialization logic

arch @ e1ae334f

-Subproject commit 9336bbac1c82d417d65d0a973359e4fad25e2dd1
+Subproject commit e1ae334ff043872b3678fc7fd48bea6125e8ea44

include/nuttx/arch.h

@@ -1753,6 +1753,28 @@ int up_cpu_index(void);
 int up_cpu_start(int cpu);
 #endif
 
+/****************************************************************************
+ * Name: up_cpu_initialize
+ *
+ * Description:
+ *   After the CPU has been started (via up_cpu_start()) the system will
+ *   call back into the architecture-specific code with this function on the
+ *   thread of execution of the newly started CPU.  This gives the
+ *   architecture-specific a chance to perform ny initial, CPU-specific
+ *   initialize on that thread.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   Zero on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SMP
+int up_cpu_initialize(void);
+#endif
+
 /****************************************************************************
  * Name: up_cpu_pause
  *

sched/init/os_smpstart.c

@@ -80,11 +80,14 @@ static const char g_idlename[] = "CPUn Idle"
  * Name: os_idle_trampoline
  *
  * Description:
- *   This is the common IDLE task for CPUs 1 through (CONFIG_SMP_NCPUS-1).
- *   It is equivalent to the CPU 0 IDLE logic in os_start.c
+ *   This is the common start-up logic for the IDLE task for CPUs 1 through
+ *   (CONFIG_SMP_NCPUS-1).  Having a start-up function such as this for the
+ *   IDLE is not really an architectural necessity.  It is used only for
+ *   symmetry with now other threads are started (see task_start() and
+ *   pthread_start()).
  *
  * Input Parameters:
- *   Standard task arguments.
+ *   None.
  *
  * Returned Value:
  *   This function does not return.
@@ -93,7 +96,11 @@ static const char g_idlename[] = "CPUn Idle"
 
 void os_idle_trampoline(void)
 {
-  /* Transfer control to the IDLE task */
+  /* Perform architecture-specific initialization for this CPU */
+
+  up_cpu_initialize();
+
+  /* Then transfer control to the IDLE task */
 
   (void)os_idle_task(0, NULL);