// -*- mode:doc; -*-
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=== Tips and tricks

[[package-name-variable-relation]]
==== Package name, config entry name and makefile variable relationship

In Buildroot, there is some relationship between:

* the _package name_, which is the package directory name (and the
  name of the +*.mk+ file);

* the config entry name that is declared in the +Config.in+ file;

* the makefile variable prefix.

It is mandatory to maintain consistency between these elements,
using the following rules:

* the package directory and the +*.mk+ name are the _package name_
  itself (e.g.: +package/foo-bar_boo/foo-bar_boo.mk+);

* the _make_ target name is the _package name_ itself (e.g.:
  +foo-bar_boo+);

* the config entry is the upper case _package name_ with `.` and `-`
  characters substituted with `_`, prefixed with +BR2_PACKAGE_+ (e.g.:
  +BR2_PACKAGE_FOO_BAR_BOO+);

* the +*.mk+ file variable prefix is the upper case _package name_
  with `.` and `-` characters substituted with `_` (e.g.:
  +FOO_BAR_BOO_VERSION+).


[[github-download-url]]
==== How to add a package from GitHub

Packages on GitHub often don't have a download area with release tarballs.
However, it is possible to download tarballs directly from the repository
on GitHub. As GitHub is known to have changed download mechanisms in the
past, the 'github' helper function should be used as shown below.

------------------------
FOO_VERSION = v1.0 # tag or full commit ID
FOO_SITE = $(call github,<user>,<package>,$(FOO_VERSION))
------------------------

.Notes
- The FOO_VERSION can either be a tag or a commit ID.
- The tarball name generated by github matches the default one from
  Buildroot (e.g.: +foo-f6fb6654af62045239caed5950bc6c7971965e60.tar.gz+),
  so it is not necessary to specify it in the +.mk+ file.
- When using a commit ID as version, you should use the full 40 hex characters.