// which prevents us from allocating more stack.
//
//go:nosplit
func sysAllocOS(n uintptr) unsafe.Pointer {
	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
}

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
	r := stdcall3(_VirtualFree, uintptr(v), n, _MEM_DECOMMIT)
	if r != 0 {
		return
	}

	// Decommit failed. Usual reason is that we've merged memory from two different

//
//go:nosplit
func sysAllocOS(n uintptr) unsafe.Pointer {
	v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
	if err != 0 {
		return nil
	}
	return v
}

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
	// MADV_FREE_REUSABLE is like MADV_FREE except it also propagates
	// accounting information about the process to task_info.
	madvise(v, n, _MADV_FREE_REUSABLE)
}

			exit(2)
		}
		if err == _EAGAIN {
			print("runtime: mmap: too much locked memory (check 'ulimit -l').\n")
			exit(2)
		}
		return nil
	}
	return p
}

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
	madvise(v, n, _MADV_DONTNEED)
}

func sysUsedOS(v unsafe.Pointer, n uintptr) {
}

func sysHugePageOS(v unsafe.Pointer, n uintptr) {
}

//
//go:nosplit
func sysAllocOS(n uintptr) unsafe.Pointer {
	v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
	if err != 0 {
		return nil
	}
	return v
}

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
	if debug.madvdontneed != 0 {
		madvise(v, n, _MADV_DONTNEED)
	} else {
		madvise(v, n, _MADV_FREE)
	}
}

func sysUsedOS(v unsafe.Pointer, n uintptr) {
}

		// Can't actually shrink address space because segment is shared.
		memclrNoHeapPointers(v, n)
		bloc -= n
	} else {
		memFree(v, n)
		memCheck()
	}
	unlock(&memlock)
}

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
}

func sysUsedOS(v unsafe.Pointer, n uintptr) {
}

func sysHugePageOS(v unsafe.Pointer, n uintptr) {
}

func sysNoHugePageOS(v unsafe.Pointer, n uintptr) {
}

			print("runtime: mmap: too much locked memory (check 'ulimit -l').\n")
			exit(2)
		}
		return nil
	}
	return p
}

var adviseUnused = uint32(_MADV_FREE)

const madviseUnsupported = 0

func sysUnusedOS(v unsafe.Pointer, n uintptr) {
	if uintptr(v)&(physPageSize-1) != 0 || n&(physPageSize-1) != 0 {
		// madvise will round this to any physical page
		// *covered* by this range, so an unaligned madvise

// sysUnused memory region are considered forfeit and the region must not be
// accessed again until sysUsed is called.
func sysUnused(v unsafe.Pointer, n uintptr) {
	gcController.mappedReady.Add(-int64(n))
	sysUnusedOS(v, n)
}

// sysUsed transitions a memory region from Prepared to Ready. It notifies the
// operating system that the memory region is needed and ensures that the region