- * - If the context_switch flag is set, indicating that there are more
- * threads waiting to run, we yield to the scheduler
+ * - If HpLim==0, indicating that we should context-switch, we yield
+ * to the scheduler (return ThreadYielding).
+ *
+ * - If the context_switch flag is set (the backup plan if setting HpLim
+ * to 0 didn't trigger a context switch), we yield to the scheduler