int i;
	stack_t nss;
	struct timespec ts;

	// Set up an alternate signal stack for this thread.
	memset(&ss, 0, sizeof ss);
	ss.ss_sp = malloc(CSIGSTKSZ);
	if (ss.ss_sp == NULL) {
		die("malloc");
	}
	ss.ss_flags = 0;
	ss.ss_size = CSIGSTKSZ;
	if (sigaltstack(&ss, NULL) < 0) {
		die("sigaltstack");
	}

	// Send ourselves a SIGIO.  This will be caught by the Go
	// signal handler which should forward to the C signal

		abort();
	}
	stack_t st = {}, ost = {};
	st.ss_sp = (char*)base;
	st.ss_flags = 0;
	st.ss_size = CSIGSTKSZ;
	if (sigaltstack(&st, &ost) < 0) {
		perror("sigaltstack failed");
		abort();
	}

	// Call Go.
	SigStackCallback();

	// Disable signal stack and protect it so we can detect reuse.
	if (ost.ss_flags & SS_DISABLE) {
		// Darwin libsystem has a bug where it checks ss_size

type usigset struct {
	val [16]uint64
}

type stackt struct {
	ss_sp     *byte
	ss_flags  int32
	pad_cgo_0 [4]byte
	ss_size   uintptr
}

type sigcontext struct {
	sc_pc         uint64
	sc_regs       [32]uint64
	sc_flags      uint32
	sc_extcontext [0]uint64
}

type ucontext struct {
	uc_flags     uint64
	uc_link      *ucontext
	uc_stack     stackt
	uc_sigmask   usigset

	tid1       unsafe.Pointer // *int32
	tid2       unsafe.Pointer // *int32
}

type sigset struct {
	__bits [4]uint32
}

type stackt struct {
	ss_sp     uintptr
	ss_size   uintptr
	ss_flags  int32
	pad_cgo_0 [4]byte
}

type siginfo struct {
	si_signo  int32
	si_errno  int32
	si_code   int32
	si_pid    int32
	si_uid    uint32
	si_status int32
	si_addr   uint64

	_SA_RESTORER = 0
)

type stackt struct {
	ss_sp    *byte
	ss_flags int32
	ss_size  uintptr
}

type sigcontext struct {
	psw_mask uint64
	psw_addr uint64
	gregs    [16]uint64
	aregs    [16]uint32
	fpc      uint32
	fpregs   [16]uint64
}

type ucontext struct {
	uc_flags    uint64
	uc_link     *ucontext
	uc_stack    stackt
	uc_mcontext sigcontext

}

type siginfo struct {
	si_signo  int32
	si_code   int32
	si_errno  int32
	pad_cgo_0 [4]byte
	_data     [120]byte
}

type stackt struct {
	ss_sp     uintptr
	ss_size   uintptr
	ss_flags  int32
	pad_cgo_0 [4]byte
}

type timespec struct {
	tv_sec  int64
	tv_nsec int64
}

//go:nosplit
func (ts *timespec) setNsec(ns int64) {
	ts.tv_sec = ns / 1e9
	ts.tv_nsec = ns % 1e9

	// in minit, but it's a simple change that keeps NetBSD
	// working like other OS's. At this point all signals are
	// blocked, so there is no race.
	memset(&ss, 0, sizeof ss);
	ss.ss_flags = SS_DISABLE;
	sigaltstack(&ss, nil);

	crosscall1(ts.fn, setg_gcc, ts.g);
	return nil;

	fp_fcsr  uint64
	fp_flags int32
	pad      int32
}

type mcontext struct {
	mc_gpregs gpregs
	mc_fpregs fpregs
	mc_flags  int32
	mc_pad    int32
	mc_spare  [8]uint64
}

type ucontext struct {
	uc_sigmask  sigset
	uc_mcontext mcontext
	uc_link     *ucontext
	uc_stack    stackt
	uc_flags    int32
	__spare__   [4]int32
	pad_cgo_0   [12]byte
}

	fp_sr    uint32
	fp_cr    uint32
	fp_flags int32
	fp_pad   int32
}

type mcontext struct {
	mc_gpregs gpregs
	mc_fpregs fpregs
	mc_flags  int32
	mc_pad    int32
	mc_spare  [8]uint64
}

type ucontext struct {
	uc_sigmask  sigset
	uc_mcontext mcontext
	uc_link     *ucontext
	uc_stack    stackt
	uc_flags    int32
	__spare__   [4]int32
	pad_cgo_0   [12]byte
}

	_O_CREAT    = 0x40
	_O_TRUNC    = 0x200
	_O_NONBLOCK = 0x800
	_O_CLOEXEC  = 0x80000
)

type usigset struct {
	__val [16]uint64
}

type stackt struct {
	ss_sp     *byte
	ss_flags  int32
	pad_cgo_0 [4]byte
	ss_size   uintptr
}

type sigcontext struct {
	fault_address uint64
	/* AArch64 registers */
	regs       [31]uint64
	sp         uint64
	pc         uint64