go/src/cmd/link/internal/ld/outbuf_mmap.go

// Mmap maps the output file with the given size. It unmaps the old mapping
// if it is already mapped. It also flushes any in-heap data to the new
// mapping.
func (out *OutBuf) Mmap(filesize uint64) (err error) { … }

func (out *OutBuf) munmap() { … }