traceEventMigrateThread (from, tso, to->no);
// ThreadMigrating tells the target cap that it needs to be added to
// the run queue when it receives the MSG_TRY_WAKEUP.
- tso->what_next = ThreadMigrating;
+ tso->why_blocked = ThreadMigrating;
tso->cap = to;
tryWakeupThread(from, tso);
}