Index: kernel/generic/src/smp/smp_call.c
===================================================================
--- kernel/generic/src/smp/smp_call.c	(revision 991d2d88d7bd9717574341fafeefffc28890114c)
+++ kernel/generic/src/smp/smp_call.c	(revision 4f5e1c7c92f197446ceb7d6406c1f5233ad02527)
@@ -107,5 +107,11 @@
 	smp_call_t *call_info)
 {
-	/* todo: doc deadlock */
+	/* 
+	 * Interrupts must not be disabled or you run the risk of a deadlock 
+	 * if both the destination and source cpus try to send an IPI to each
+	 * other with interrupts disabled. Because the interrupts are disabled 
+	 * the IPIs cannot be delivered and both cpus will forever busy wait 
+	 * for an acknowledgment of the IPI from the other cpu.
+	 */
 	ASSERT(!interrupts_disabled());
 	ASSERT(call_info != NULL);