sigfillset(&ign);
	pthread_sigmask(SIG_SETMASK, &ign, &oset);

	// Start a thread to handle exceptions.
	uintptr_t port_set = (uintptr_t)mach_exception_handler_port_set;
	pthread_attr_init(&attr);
	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
	ret = _cgo_try_pthread_create(&thr, &attr, mach_exception_handler, (void*)port_set);

	pthread_sigmask(SIG_SETMASK, &oset, nil);