-/*
- * This type is returned to the scheduler by a thread that has
- * stopped for one reason or another.
+/*
+ * Flags for the tso->flags field.
+ *
+ * The TSO_DIRTY flag indicates that this TSO's stack should be
+ * scanned during garbage collection. The link field of a TSO is
+ * always scanned, so we don't have to dirty a TSO just for linking
+ * it on a different list.
+ *
+ * TSO_DIRTY is set by
+ * - schedule(), just before running a thread,
+ * - raiseAsync(), because it modifies a thread's stack
+ * - resumeThread(), just before running the thread again
+ * and unset by the garbage collector (only).