[PATCH] NOMMU: Add docs about shared memory

Add documentation about using shared memory in NOMMU mode.

Signed-off-by: David Howells <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/nommu-mmap.txt

···
      with character device files, pipes, fifos and sockets.
 
 
+==========================
+INTERPROCESS SHARED MEMORY
+==========================
+
+Both SYSV IPC SHM shared memory and POSIX shared memory is supported in NOMMU
+mode.  The former through the usual mechanism, the latter through files created
+on ramfs or tmpfs mounts.
+
+
 =============
 NO-MMU MREMAP
 =============