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);

	if (ret) {

	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	var ret int32
	for tries := 0; tries < 20; tries++ {
		// pthread_create can fail with EAGAIN for no reasons
		// but it will be ok if it retries.
		ret = pthread_create(&tid, &attr, fn, nil)
		if ret != _EAGAIN {
			break
		}
		usleep(uint32(tries+1) * 1000) // Milliseconds.
	}
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if ret != 0 {

	var oset sigset
	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)

	lwp_mcontext_init(&uc.uc_mcontext, stk, mp, mp.g0, abi.FuncPCABI0(netbsdMstart))

	ret := retryOnEAGAIN(func() int32 {
		errno := lwp_create(unsafe.Pointer(&uc), _LWP_DETACHED, unsafe.Pointer(&mp.procid))
		// lwp_create returns negative errno
		return -errno
	})
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if ret != 0 {

			}
		}
		sigprocmask(_SIG_SETMASK, &sigBlocked, nil)
		for {
			select {
			case sig := <-enableSigChan:
				if sig > 0 {
					sigdelset(&sigBlocked, int(sig))
				}
			case sig := <-disableSigChan:
				if sig > 0 && blockableSig(sig) {
					sigaddset(&sigBlocked, int(sig))
				}
			}
			sigprocmask(_SIG_SETMASK, &sigBlocked, nil)
			maskUpdatedChan <- struct{}{}

	// Disable signals during create, so that the new thread starts
	// with signals disabled. It will enable them in minit.
	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	ret = retryOnEAGAIN(func() int32 {
		return pthread_create(&tid, &attr, abi.FuncPCABI0(tstart_sysvicall), unsafe.Pointer(mp))
	})
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if ret != 0 {
		print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", ret, ")\n")

)

const (
	POLLRDHUP = 0x2000
)

type Sigset_t struct {
	Val [16]uint64
}

const _C__NSIG = 0x80

const (
	SIG_BLOCK   = 0x1
	SIG_UNBLOCK = 0x2
	SIG_SETMASK = 0x3
)

type Siginfo struct {
	Signo int32
	Code  int32
	Errno int32
	_     int32
	_     [112]byte
}

type Termios struct {
	Iflag  uint32
	Oflag  uint32
	Cflag  uint32

)

const (
	POLLRDHUP = 0x2000
)

type Sigset_t struct {
	Val [32]uint32
}

const _C__NSIG = 0x80

const (
	SIG_BLOCK   = 0x1
	SIG_UNBLOCK = 0x2
	SIG_SETMASK = 0x3
)

type Siginfo struct {
	Signo int32
	Code  int32
	Errno int32
	_     [116]byte
}

type Termios struct {
	Iflag  uint32
	Oflag  uint32
	Cflag  uint32
	Lflag  uint32

)

const (
	POLLRDHUP = 0x2000
)

type Sigset_t struct {
	Val [16]uint64
}

const _C__NSIG = 0x41

const (
	SIG_BLOCK   = 0x0
	SIG_UNBLOCK = 0x1
	SIG_SETMASK = 0x2
)

type Siginfo struct {
	Signo int32
	Errno int32
	Code  int32
	_     int32
	_     [112]byte
}

type Termios struct {
	Iflag  uint32
	Oflag  uint32
	Cflag  uint32

)

const (
	POLLRDHUP = 0x2000
)

type Sigset_t struct {
	Val [32]uint32
}

const _C__NSIG = 0x41

const (
	SIG_BLOCK   = 0x0
	SIG_UNBLOCK = 0x1
	SIG_SETMASK = 0x2
)

type Siginfo struct {
	Signo int32
	Errno int32
	Code  int32
	_     [116]byte
}

type Termios struct {
	Iflag  uint32
	Oflag  uint32
	Cflag  uint32
	Lflag  uint32

)

const (
	POLLRDHUP = 0x2000
)

type Sigset_t struct {
	Val [16]uint64
}

const _C__NSIG = 0x41

const (
	SIG_BLOCK   = 0x0
	SIG_UNBLOCK = 0x1
	SIG_SETMASK = 0x2
)

type Siginfo struct {
	Signo int32
	Errno int32
	Code  int32
	_     int32
	_     [112]byte
}

type Termios struct {
	Iflag  uint32
	Oflag  uint32
	Cflag  uint32