TDB_VFORK
td->td_dbgflags |= TDB_VFORK;
if (td->td_dbgflags & TDB_VFORK) {
td->td_dbgflags &= ~TDB_VFORK;
if (td2->td_dbgflags & TDB_VFORK)
} else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
TDB_VFORK)