49.12. Summary

The mmap() system call creates a new memory mapping in the calling process’s virtual address space. The munmap() system call performs the converse operation, removing a mapping from a process’s address space.

A mapping may be of two types: file-based or anonymous. A file mapping maps the contents of a file region into the process’s virtual address space. An anonymous mapping (created by using the MAP_ANONYMOUS flag or by mapping /dev/zero) doesn’t have a corresponding file region; the bytes of the mapping are initialized to 0.