--- libaitsched/src/tasks.c	2013/08/15 17:58:31	1.16.6.2
+++ libaitsched/src/tasks.c	2013/08/15 19:06:20	1.16.6.4
@@ -3,7 +3,7 @@
 *  by Michael Pounov <misho@openbsd-bg.org>
 *
 * $Author: misho $
-* $Id: tasks.c,v 1.16.6.2 2013/08/15 17:58:31 misho Exp $
+* $Id: tasks.c,v 1.16.6.4 2013/08/15 19:06:20 misho Exp $
 *
 **************************************************************************
 The ELWIX and AITNET software is distributed under the following
@@ -1329,14 +1329,15 @@ schedThread(sched_root_task_t * __restrict root, sched
  * @func = task execution function
  * @arg = 1st func argument
  * @ts = timeout argument structure, minimum alarm timer resolution is 1msec!
- * @opt_data = RTC ID
- * @opt_dlen = Optional data length
+ * @opt_data = Optional RTC ID
+ * @opt_dlen = Optional Signal No.
  * return: NULL error or !=NULL new queued task
  */
 sched_task_t *
 schedRTC(sched_root_task_t * __restrict root, sched_task_func_t func, void *arg, struct timespec ts, 
 		void *opt_data, size_t opt_dlen)
 {
+#if defined(HAVE_TIMER_CREATE) && defined(HAVE_TIMER_SETTIME)
 	sched_task_t *task;
 	void *ptr;
 
@@ -1374,4 +1375,8 @@ schedRTC(sched_root_task_t * __restrict root, sched_ta
 		task = sched_unuseTask(task);
 
 	return task;
+#else
+	sched_SetErr(ENOTSUP, "Not supported realtime clock extensions");
+	return NULL;
+#endif
 }