diff --git a/ChangeLog b/ChangeLog
index 36077eb2d4..c8209c9b9b 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -11473,4 +11473,11 @@
 	  needed to supports spinlocks (2016-02-09).
 	* include/nuttx/spinlock.h:  Add basic definitions for spinlocks.  Not yet
 	  used by NuttX (2016-02-09).
+	* include/nuttx/arch.h, sched/sched/sched.h:  Add some basic definitions
+	  that may be needed for SMP support (2016-02-10).
+	* sched/init/os_start.c, sched/init/os_smpstart.c, and include/nuttx/arch.h:
+	  Add some tentative SMP start-up logic (2016-02-10).
+	* arch/arm/sim/up_head.c and up_simsmp.c:  Add multi-CPU support to the
+	  simulation to support SMP investigation..  Currently crashes when CONFIG_SMP
+	  is enabled as expected (2016-02-10).
 
diff --git a/arch b/arch
index 0ddf09674e..d0e073560a 160000
--- a/arch
+++ b/arch
@@ -1 +1 @@
-Subproject commit 0ddf09674eb2115ecfedaa82e21a2c43fc09d127
+Subproject commit d0e073560a899d50196e487247ccab7d7f74abec
diff --git a/include/nuttx/arch.h b/include/nuttx/arch.h
index 580ba4bd5e..488cbb9815 100644
--- a/include/nuttx/arch.h
+++ b/include/nuttx/arch.h
@@ -1702,8 +1702,7 @@ int up_cpundx(void);
  *   idletask - The entry point to the IDLE task.
  *
  * Returned Value:
- *   An integer index in the range of 0 through (CONFIG_SMP_NCPUS-1) that
- *   corresponds to the currently executing CPU.
+ *   Zero on success; a negated errno value on failure.
  *
  ****************************************************************************/