// -*- mode:doc; -*-
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  [[legal-info]]
  
  == Legal notice and licensing
  
  === Complying with open source licenses
  
  All of the end products of Buildroot (toolchain, root filesystem, kernel,
  bootloaders) contain open source software, released under various licenses.
  
  Using open source software gives you the freedom to build rich embedded
  systems, choosing from a wide range of packages, but also imposes some
  obligations that you must know and honour.
  Some licenses require you to publish the license text in the documentation of
  your product. Others require you to redistribute the source code of the
  software to those that receive your product.
  
  The exact requirements of each license are documented in each package, and
  it is your responsibility (or that of your legal office) to comply with those
  requirements.
  To make this easier for you, Buildroot can collect for you some material you
  will probably need. To produce this material, after you have 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/+ and
    +host-sources/+ subdirectories for target and host packages respectively.
    The source code for packages that set +<PKG>_REDISTRIBUTE = NO+ will not be
    saved.
    Patches that were applied are also saved, along with a file named +series+
    that lists the patches in the order they were applied. Patches are under the
    same license as the files that they modify.
    Note: Buildroot applies additional patches to Libtool scripts of
    autotools-based packages. These patches can be found under
    +support/libtool+ in the Buildroot source and, due to technical
    limitations, are not saved with the package sources. You may need to
    collect them manually.
  * A manifest file (one for host and one for target packages) listing the
    configured packages, their version, license and related information.
    Some of this information might not be defined in Buildroot; such items are
    marked as "unknown".
  * The license texts of all packages, in the +licenses/+ and +host-licenses/+
    subdirectories for target and host packages respectively.
    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. Certainly, more material is produced than is
  needed for a strict legal compliance. For example, it produces the source code
  for packages released under BSD-like licenses, that you are not required 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 (including patches to packages for which source
  distribution is required).
  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]]
  === License abbreviations
  
  Here is a list of the licenses that are most widely used by packages in
  Buildroot, with the name used in the manifest files:
  
  * `AGPLv3`:
    http://www.gnu.org/licenses/agpl-3.0.en.html[
    GNU Affero General Public License, version 3];
  * `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`:
    http://www.gnu.org/licenses/old-licenses/lgpl-2.0.html[
    GNU Library General Public License, version 2];
  * `LGPLv2+`:
    http://www.gnu.org/licenses/old-licenses/lgpl-2.0.html[
    GNU Library General Public License, version 2]
    or (at your option) any later 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`:
    http://directory.fsf.org/wiki/License:BSD_4Clause[
    Original BSD 4-clause license];
  * `BSD-3c`:
    http://opensource.org/licenses/BSD-3-Clause[
    BSD 3-clause license];
  * `BSD-2c`:
    http://opensource.org/licenses/BSD-2-Clause[
    BSD 2-clause license];
  * `MIT`:
    http://opensource.org/licenses/mit-license.html[
    MIT-style license];
  * `Apache-2.0`:
    http://apache.org/licenses/LICENSE-2.0.html[
    Apache License, version 2.0];
  
  [[legal-info-buildroot]]
  === Complying with the Buildroot license
  
  Buildroot itself is an open source 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, with
  the exception of the package patches detailed below.
  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 that this is only the Buildroot developers' opinion, and you
  should consult your legal department or lawyer in case of any doubt.
  
  ==== Patches to packages
  
  Buildroot also bundles patch files, which are applied to the sources
  of the various packages. Those patches are not covered by the license
  of Buildroot. Instead, they are covered by the license of the software
  to which the patches are applied. When said software is available
  under multiple licenses, the Buildroot patches are only provided under
  the publicly accessible licenses.
  
  See xref:patch-policy[] for the technical details.