diff --git a/include/nuttx/arch.h b/include/nuttx/arch.h
index 22b5ebb337..b2da611d1b 100644
--- a/include/nuttx/arch.h
+++ b/include/nuttx/arch.h
@@ -1821,6 +1821,10 @@ int up_cpu_start(int cpu);
  * Returned Value:
  *   Zero on success; a negated errno value on failure.
  *
+ * Assumptions:
+ *   Called from within a critical section; up_cpu_resume() must be called
+ *   later while still within the same critical section.
+ *
  ****************************************************************************/
 
 #ifdef CONFIG_SMP
@@ -1894,6 +1898,10 @@ int up_cpu_paused(int cpu);
  * Returned Value:
  *   Zero on success; a negated errno value on failure.
  *
+ * Assumptions:
+ *   Called from within a critical section; up_cpu_pause() must have
+ *   previously been called within the same critical section.
+ *
  ****************************************************************************/
 
 #ifdef CONFIG_SMP