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 {

	"unsafe"
)

const (
	_NSIG        = 33
	_SI_USER     = 0
	_SS_DISABLE  = 4
	_SIG_BLOCK   = 1
	_SIG_UNBLOCK = 2
	_SIG_SETMASK = 3
)

type mOS struct{}

//go:noescape
func lwp_create(param *lwpparams) int32

//go:noescape
func sigaltstack(new, old *stackt)

//go:noescape
func sigaction(sig uint32, new, old *sigactiont)

//go:noescape
func sigprocmask(how int32, new, old *sigset)

#define SYS_sched_yield			350
#define SYS___setitimer50		425
#define SYS___clock_gettime50		427
#define SYS___nanosleep50		430
#define SYS___kevent50			435
#define SYS____lwp_park60		478

// int32 lwp_create(void *context, uintptr flags, void *lwpid)
TEXT runtime·lwp_create(SB),NOSPLIT,$0
	MOVQ	ctxt+0(FP), DI
	MOVQ	flags+8(FP), SI
	MOVQ	lwpid+16(FP), DX
	MOVL	$SYS__lwp_create, AX
	SYSCALL
	JCC	2(PC)
	NEGQ	AX

	MOVL $470, AX		// umtx_wakeup
	SYSCALL
	JCC	2(PC)
	NEGQ	AX
	MOVL	AX, ret+16(FP)
	RET

TEXT runtime·lwp_create(SB),NOSPLIT,$0
	MOVQ param+0(FP), DI		// arg 1 - params
	MOVL $495, AX		// lwp_create
	SYSCALL
	MOVL	AX, ret+8(FP)
	RET

TEXT runtime·lwp_start(SB),NOSPLIT,$0
	MOVQ	DI, R13 // m

	// set up FS to point at m->tls
	LEAQ	m_tls(R13), DI
	CALL	runtime·settls(SB)	// smashes DI

	MOVW	fd+0(FP), R0	// arg 1 - fd
	MOVW	p+4(FP), R1	// arg 2 - buf
	MOVW	n+8(FP), R2	// arg 3 - nbyte
	SWI $SYS_write
	RSB.CS	$0, R0		// caller expects negative errno
	MOVW	R0, ret+12(FP)
	RET

// int32 lwp_create(void *context, uintptr flags, void *lwpid)
TEXT runtime·lwp_create(SB),NOSPLIT,$0
	MOVW ctxt+0(FP), R0
	MOVW flags+4(FP), R1
	MOVW lwpid+8(FP), R2
	SWI $SYS__lwp_create
	MOVW	R0, ret+12(FP)
	RET

	MOVL	BX, 4(SP)
	MOVL	40(SP), BX // context
	MOVL	BX, 8(SP)
	CALL	runtime·sigtrampgo(SB)

	MOVL	di-16(SP), DI
	MOVL	si-12(SP), SI
	MOVL	bp-8(SP),  BP
	MOVL	bx-4(SP),  BX
	RET

// int32 lwp_create(void *context, uintptr flags, void *lwpid);
TEXT runtime·lwp_create(SB),NOSPLIT,$16
	MOVL	$0, 0(SP)
	MOVL	ctxt+0(FP), AX
	MOVL	AX, 4(SP)		// arg 1 - context
	MOVL	flags+4(FP), AX
	MOVL	AX, 8(SP)		// arg 2 - flags

#define SYS___setitimer50		425
#define SYS___clock_gettime50		427
#define SYS___nanosleep50		430
#define SYS___kevent50			435
#define SYS_pipe2			453
#define SYS_openat			468
#define SYS____lwp_park60		478

// int32 lwp_create(void *context, uintptr flags, void *lwpid)
TEXT runtime·lwp_create(SB),NOSPLIT,$0
	MOVD	ctxt+0(FP), R0
	MOVD	flags+8(FP), R1
	MOVD	lwpid+16(FP), R2
	SVC	$SYS__lwp_create
	BCC	ok
	NEG	R0, R0
ok:

	SYS_VMSPACE_PWRITE         = 493 // { ssize_t vmspace_pwrite(void *id, const void *buf, \
	SYS_EXTEXIT                = 494 // { void extexit(int how, int status, void *addr); }
	SYS_LWP_CREATE             = 495 // { int lwp_create(struct lwp_params *params); }
	SYS_LWP_GETTID             = 496 // { lwpid_t lwp_gettid(void); }
	SYS_LWP_KILL               = 497 // { int lwp_kill(pid_t pid, lwpid_t tid, int signum); }

	SYS_EXTEXIT                = 494 // { void extexit(int how, int status, void *addr); }
	SYS_LWP_CREATE             = 495 // { int lwp_create(struct lwp_params *params); }
	SYS_LWP_GETTID             = 496 // { lwpid_t lwp_gettid(void); }
	SYS_LWP_KILL               = 497 // { int lwp_kill(pid_t pid, lwpid_t tid, int signum); }

	SYS_GETCONTEXT           = 307 // { int|sys||getcontext(struct __ucontext *ucp); }
	SYS_SETCONTEXT           = 308 // { int|sys||setcontext(const struct __ucontext *ucp); }
	SYS__LWP_CREATE          = 309 // { int|sys||_lwp_create(const struct __ucontext *ucp, u_long flags, lwpid_t *new_lwp); }
	SYS__LWP_EXIT            = 310 // { int|sys||_lwp_exit(void); }
	SYS__LWP_SELF            = 311 // { lwpid_t|sys||_lwp_self(void); }