Tmpfs POSIX Access Control Lists

configname: CONFIG_TMPFS_POSIX_ACL

Linux Kernel Configuration
└─>File systems
└─>Pseudo filesystems
└─>Tmpfs POSIX Access Control Lists
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
POSIX Access Control Lists (ACLs) support additional access rights
for users and groups beyond the standard owner/group/world scheme,
and this option selects support for ACLs specifically for tmpfs
filesystems.

If you've selected TMPFS, it's possible that you'll also need
this option as there are a number of Linux distros that require
POSIX ACL support under /dev for certain features to work properly.
For example, some distros need this feature for ALSA-related /dev
files for sound to work properly. In short, if you're not sure,
say Y.