SIGNAL_FLAG_SEND_TO_THREAD
SIGNAL_FLAG_SEND_TO_THREAD | SIGNAL_FLAG_QUEUING_REQUIRED);
flags &= SIGNAL_FLAG_QUEUING_REQUIRED | SIGNAL_FLAG_SEND_TO_THREAD;
if ((flags & SIGNAL_FLAG_SEND_TO_THREAD) != 0 || id < 0)
return _kern_send_signal(thread, sig, NULL, SIGNAL_FLAG_SEND_TO_THREAD);