buildroot

// -*- mode:doc; -*-

// vim: set syntax=asciidoc:

​

[[customize-device-permission]]

==== Setting file permissions and ownership and adding custom devices nodes

​

Sometimes it is needed to set specific permissions or ownership on files

or device nodes. For example, certain files may need to be owned by

root. Since the post-build scripts are not run as root, you cannot do

such changes from there unless you use an explicit fakeroot from the

post-build script.

​

Instead, Buildroot provides support for so-called _permission tables_.

To use this feature, set config option +BR2_ROOTFS_DEVICE_TABLE+ to a

space-separated list of permission tables, regular text files following

the xref:makedev-syntax[makedev syntax].

​

If you are using a static device table (i.e. not using +devtmpfs+,

+mdev+, or +(e)udev+) then you can add device nodes using the same

syntax, in so-called _device tables_. To use this feature, set config

option +BR2_ROOTFS_STATIC_DEVICE_TABLE+ to a space-separated list of

device tables.

​

As shown in xref:customize-dir-structure[], the recommended location for

such files is +board/<company>/<boardname>/+.

​

It should be noted that if the specific permissions or device nodes are

related to a specific application, you should set variables

+FOO_PERMISSIONS+ and +FOO_DEVICES+ in the package's +.mk+ file instead

(see xref:generic-package-reference[]).