PROT_NONE  = C.PROT_NONE
	PROT_READ  = C.PROT_READ
	PROT_WRITE = C.PROT_WRITE
	PROT_EXEC  = C.PROT_EXEC

	MAP_ANON    = C.MAP_ANON
	MAP_PRIVATE = C.MAP_PRIVATE
	MAP_FIXED   = C.MAP_FIXED
	MAP_STACK   = C.MAP_STACK

	MADV_DONTNEED = C.MADV_DONTNEED
	MADV_FREE     = C.MADV_FREE

	SA_SIGINFO = C.SA_SIGINFO
	SA_RESTART = C.SA_RESTART
	SA_ONSTACK = C.SA_ONSTACK

	PTHREAD_CREATE_DETACHED = C.PTHREAD_CREATE_DETACHED

	stk := unsafe.Pointer(mp.g0.stack.hi)
	if false {
		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " id=", mp.id, " ostk=", &mp, "\n")
	}

	// Stack pointer must point inside stack area (as marked with MAP_STACK),
	// rather than at the top of it.
	param := tforkt{
		tf_tcb:   unsafe.Pointer(&mp.tls[0]),
		tf_tid:   nil, // minit will record tid
		tf_stack: uintptr(stk) - goarch.PtrSize,
	}

	var oset sigset

}

//go:nosplit
func validSIGPROF(mp *m, c *sigctxt) bool {
	return true
}

func osStackAlloc(s *mspan) {
	osStackRemap(s, _MAP_STACK)
}

func osStackFree(s *mspan) {
	// Undo MAP_STACK.
	osStackRemap(s, 0)
}

func osStackRemap(s *mspan, flags int32) {
	a, err := mmap(unsafe.Pointer(s.base()), s.npages*pageSize, _PROT_READ|_PROT_WRITE, _MAP_PRIVATE|_MAP_ANON|_MAP_FIXED|flags, -1, 0)