kumquat-buildroot/docs/manual/legal-notice.txt

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

[[legal-info]]

Legal notice and licensing
==========================

Complying with opensource licenses
----------------------------------

All of the end products of Buildroot (toolchain, root filesystem, kernel,
bootloaders) contain opensource software, released under various licenses.

Using opensource software gives you the freedom to build rich embedded
systems choosing from a wide range of packages, but also gives some
obligations that you must know and honour.
Some licenses require you to publish the license text in the documentation of
your product. Other require you to redistribute the source code of the
software to those that receive your product.

The exact requirements of each license is documented in each package, and it is
your (or your legal office's) responsibility to comply with these requirements.
To make this easier for you, Buildroot can collect for you some material you
will probably need. To produce this material, after you configured Buildroot
with +make menuconfig+, +make xconfig+ or +make gconfig+, run:

--------------------
make legal-info
--------------------

Buildroot will collect legally-relevant material in your output directory,
under the +legal-info/+ subdirectory.
There you will find:

* A +README+ file, that summarizes the produced material and contains warnings
  about material that Buildroot could not produce.
* +buildroot.config+: this is the Buildroot configuration file that is usually
  produced with +make menuconfig+, and which is necessary to reproduce the
  build.
* The source code for all packages; this is saved in the +sources/+
  subdirectory (except for proprietary packages, whose source code is not
  saved);
  patches applied to some packages by Buildroot are distributed with the
  Buildroot sources and are not duplicated in the +sources/+ subdirectory.
* A manifest file listing the configured packages, their version, license and
  related information.
  Some of these information might be not defined in Buildroot; in this case
  they are clearly marked as "unknown" or similar.
* A +licenses/+ subdirectory, which contains the license text of packages.
  If the license file(s) are not defined in Buildroot, the file is not produced
  and a warning in the +README+ indicates this.

Please note that the aim of the +legal-info+ feature of Buildroot is to
produce all the material that is somehow relevant for legal compliance with the
package licenses. Buildroot does not try to produce the exact material that
you must somehow make public. It does surely produce some more material than is
needed for a strict legal compliance. For example, it produces the source code
for packages released under BSD-like licenses, that you might not want to
redistribute in source form.

Moreover, due to technical limitations, Buildroot does not produce some
material that you will or may need, such as the toolchain source code and the
Buildroot source code itself.
When you run +make legal-info+, Buildroot produces warnings in the +README+
file to inform you of relevant material that could not be saved.

[[legal-info-list-licenses]]
Here is a list of the licenses that are most widely used by packages in
Buildroot, with the name used in the manifest file:

* +GPLv2+:
  http://www.gnu.org/licenses/old-licenses/gpl-2.0.html[
  GNU General Public License, version 2];
* +GPLv2++:
  http://www.gnu.org/licenses/old-licenses/gpl-2.0.html[
  GNU General Public License, version 2]
  or (at your option) any later version;
* +GPLv3+:
  http://www.gnu.org/licenses/gpl.html[
  GNU General Public License, version 3];
* +GPLv3++:
  http://www.gnu.org/licenses/gpl.html[
  GNU General Public License, version 3]
  or (at your option) any later version;
* +GPL+:
  http://www.gnu.org/licenses/gpl.html[
  GNU General Public License] (any version);
* +LGPLv2.1+:
  http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html[
  GNU Lesser General Public License, version 2.1];
* +LGPLv2.1++:
  http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html[
  GNU Lesser General Public License, version 2.1]
  or (at your option) any later version;
* +LGPLv3+:
  http://www.gnu.org/licenses/lgpl.html[
  GNU Lesser General Public License, version 3];
* +LGPLv3++:
  http://www.gnu.org/licenses/lgpl.html[
  GNU Lesser General Public License, version 3]
  or (at your option) any later version;
* +LGPL+:
  http://www.gnu.org/licenses/lgpl.html[
  GNU Lesser General Public License] (any version);
* +BSD-4c+: Original BSD 4-clause license;
* +BSD-3c+: BSD 3-clause license;
* +BSD-2c+: BSD 2-clause license;
* +PROPRIETARY+: marks a non-opensource package;
  Buildroot does not save any licensing info or source code for these packages.

Complying with the Buildroot license
------------------------------------

Buildroot itself is an opensource software, released under the
http://www.gnu.org/licenses/old-licenses/gpl-2.0.html[GNU General Public
License, version 2] or (at your option) any later version.
However, being a build system, it is not normally part of the end product:
if you develop the root filesystem, kernel, bootloader or toolchain for a
device, the code of Buildroot is only present on the development machine, not
in the device storage.

Nevertheless, the general view of the Buildroot developers is that you should
release the Buildroot source code along with the source code of other packages
when releasing a product that contains GPL-licensed software.
This is because the
http://www.gnu.org/licenses/old-licenses/gpl-2.0.html[GNU GPL]
defines the "'complete source code'" for an executable work as "'all the
source code for all modules it contains, plus any associated interface
definition files, plus the scripts used to control compilation and installation
of the executable'".
Buildroot is part of the 'scripts used to control compilation and
installation of the executable', and as such it is considered part of the
material that must be redistributed.

Keep in mind this is only the Buildroot developers' opinion, and you should
consult your legal department or lawyer in case of any doubt.