--- linux-2.0.35/include/linux/sched.h	Sat Jul 18 22:54:22 1998
+++ linux/include/linux/sched.h	Fri Aug  7 09:51:15 1998
@@ -93,6 +93,7 @@
 #define SCHED_OTHER		0
 #define SCHED_FIFO		1
 #define SCHED_RR		2
+#define SCHED_IDLE		3
 
 struct sched_param {
 	int sched_priority;
--- linux-2.0.35/kernel/sched.c	Sat Jul 18 22:46:51 1998
+++ linux/kernel/sched.c	Fri Aug 28 00:29:08 1998
@@ -253,6 +253,13 @@
 #endif		
 #endif
 
+	if (p->policy == SCHED_IDLE) {
+		if (p->signal & ~p->blocked)
+			return 1;
+		else
+			return -999;
+	}
+
 	/*
 	 * Realtime process, select the first one on the
 	 * runqueue (taking priorities within processes
@@ -412,6 +419,9 @@
 		prev->counter = prev->priority;
 		move_last_runqueue(prev);
 	}
+	/* switch multiple SCHED_IDLE processes */
+	if (!prev->counter && prev->policy == SCHED_IDLE)
+		move_last_runqueue(prev);
 	switch (prev->state) {
 		case TASK_INTERRUPTIBLE:
 			if (prev->signal & ~prev->blocked)
@@ -1468,16 +1478,18 @@
 	if (policy < 0)
 		policy = p->policy;
 	else if (policy != SCHED_FIFO && policy != SCHED_RR &&
-		 policy != SCHED_OTHER)
+		 policy != SCHED_OTHER && policy != SCHED_IDLE)
 		return -EINVAL;
 	
 	/*
 	 * Valid priorities for SCHED_FIFO and SCHED_RR are 1..99, valid
-	 * priority for SCHED_OTHER is 0.
+	 * priority for SCHED_OTHER and SCHED_IDLE is 0.
 	 */
-	if (lp.sched_priority < 0 || lp.sched_priority > 99)
+	if (policy == SCHED_FIFO || policy == SCHED_RR)
+	if (lp.sched_priority < 1 || lp.sched_priority > 99)
 		return -EINVAL;
-	if ((policy == SCHED_OTHER) != (lp.sched_priority == 0))
+	if (policy == SCHED_OTHER || policy == SCHED_IDLE)
+	if (lp.sched_priority != 0)
 		return -EINVAL;
 
 	if ((policy == SCHED_FIFO || policy == SCHED_RR) && !suser())
@@ -1561,6 +1573,7 @@
 	      case SCHED_RR:
 		return 99;
 	      case SCHED_OTHER:
+	      case SCHED_IDLE:
 		return 0;
 	}
 
@@ -1574,6 +1587,7 @@
 	      case SCHED_RR:
 		return 1;
 	      case SCHED_OTHER:
+	      case SCHED_IDLE:
 		return 0;
 	}
 
@@ -1641,7 +1655,7 @@
 		return -EINVAL;
 
 	if (t.tv_sec == 0 && t.tv_nsec <= 2000000L &&
-	    current->policy != SCHED_OTHER) {
+	    current->policy != SCHED_OTHER && current->policy != SCHED_IDLE) {
 		/*
 		 * Short delay requests up to 2 ms will be handled with
 		 * high precision by a busy wait for all real-time processes.