// madvise will round this to any physical page
		// *covered* by this range, so an unaligned madvise
		// will release more memory than intended.
		throw("unaligned sysUnused")
	}

	advise := atomic.Load(&adviseUnused)
	if debug.madvdontneed != 0 && advise != madviseUnsupported {
		advise = _MADV_DONTNEED
	}
	switch advise {
	case _MADV_FREE:
		if madvise(v, n, _MADV_FREE) == 0 {

//
//go:noescape
func write1(fd uintptr, p unsafe.Pointer, n int32) int32

//go:noescape
func open(name *byte, mode, perm int32) int32

// return value is only set on linux to be used in osinit().
func madvise(addr unsafe.Pointer, n uintptr, flags int32) int32

// exitThread terminates the current thread, writing *wait = freeMStack when
// the stack is safe to reclaim.
//
//go:noescape

//
//go:noescape
func write1(fd uintptr, p unsafe.Pointer, n int32) int32

//go:noescape
func open(name *byte, mode, perm int32) int32

// return value is only set on linux to be used in osinit().
func madvise(addr unsafe.Pointer, n uintptr, flags int32) int32

// exitThread terminates the current thread, writing *wait = freeMStack when
// the stack is safe to reclaim.
//
//go:noescape
func exitThread(wait *atomic.Uint32)

	KeepAlive(addr) // Just for consistency. Hopefully addr is not a Go address.
}
func munmap_trampoline()

//go:nosplit
//go:cgo_unsafe_args
func madvise(addr unsafe.Pointer, n uintptr, flags int32) {
	libcCall(unsafe.Pointer(abi.FuncPCABI0(madvise_trampoline)), unsafe.Pointer(&addr))
	KeepAlive(addr) // Just for consistency. Hopefully addr is not a Go address.
}