Commit aba0d000 authored by Thomas De Schampheleire's avatar Thomas De Schampheleire Committed by Thomas Petazzoni
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manual/user guide/customization: add section on device/permission tables 



This patch adds basic documentation on device and permission tables, a topic
which was currently not yet covered in the manual.

Signed-off-by: default avatarThomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
parent 32ef7396

docs/manual/customize-device-permission-tables.txt

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// -*- 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[]).

docs/manual/customize-rootfs.txt

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@@ -97,3 +97,5 @@ To enable this feature, enable config option 
This method is not recommended because it duplicates the entire

  skeleton, which prevents taking advantage of the fixes or improvements

  brought to the default skeleton in later Buildroot releases.



include::customize-device-permission-tables.txt[]

docs/manual/customize.txt

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@@ -16,6 +16,10 @@ Typical actions you may need to perform for a given project are: 
     +BR2_ROOTFS_POST_BUILD_SCRIPT+)

  ** running arbitrary commands prior to generating the filesystem image

     (using +BR2_ROOTFS_POST_BUILD_SCRIPT+)

  ** setting file permissions and ownership (using

     +BR2_ROOTFS_DEVICE_TABLE+)

  ** adding custom devices nodes (using

     +BR2_ROOTFS_STATIC_DEVICE_TABLE+)

* running arbitrary commands after generating the filesystem image

  (using +BR2_ROOTFS_POST_IMAGE_SCRIPT+)

* adding project-specific patches to some packages (using