sched: add function to create per-cpu idle threads

sched/thread.c

@@ -70,3 +70,21 @@ int thread_priority(struct thread *thr)
 {
 	return thr->tr_prio;
 }
+
+struct thread *create_idle_thread(void)
+{
+	struct task *idle = idle_task();
+
+	struct thread *thr = thread_alloc();
+
+	thr->tr_prio = PRIO_NORMAL;
+	thr->tr_state = THREAD_READY;
+	thr->tr_quantum_target = default_quantum();
+
+	unsigned long flags;
+	task_lock_irqsave(idle, &flags);
+	queue_push_back(&idle->t_threads, &thr->tr_threads);
+	task_unlock_irqrestore(idle, flags);
+
+	return thr;
+}