[Buildroot] Is GPLv2 the right license for Buildroot?

[Yann E. MORIN <yann.morin.1998@free.fr>]

Thomas, All,

On 2013-09-16 18:21 +0200, Thomas Petazzoni spake thusly:
> On Sun, 15 Sep 2013 00:16:13 +0200, Yann E. MORIN wrote:
> 
> > Since Buildroot's license is the GPLv2, BR2_EXTERNAL is covered by the
> > GPLv2.
> 
> Probably going to make waves,

Probably, yes. ;-)

> but I'm wondering if the GPLv2 is the
> right license for Buildroot. I believe it is not very easy to
> understand how the terms of the GPL apply to something such as a build
> system, and I am not sure that the GPL copyleft requirements are really
> benefiting to Buildroot in any way. I am pretty sure that the vast
> majority of companies using Buildroot are not really realizing it's
> licensed under the GPL and therefore are not complying with the
> Buildroot license terms (while they probably do realize that the
> kernel, U-Boot, etc. are under the GPL and comply with their terms).

On the other hand, the GPLv2 only applies at the time of distribution.
So long as the Buildroot tre is not distributed, there is no reason to
fear anything.

Now, let's try to make things clear:

  - on an embedded system, the probability that there is a GPL program
    is rather high (eg. busybox, the Linux kernel);

  - lets assume Buildroot is used to build those programs;

  - the GPL (as applied to _those_ programs, not Buildroot) mandates
    that the script to control compilation and installation of those
    programs be made available (section of GPLv2);

  - so the easiest way to comply with those programs' GPL is to
    distribute the Buildroot tree that was used to build the target
    filesystem, since it does contain all required recipes (aka the
    scripts of section 3 of the GPLv2)

  - Buildroot is itself GPLv2, so by distributing the Buildroot tree, a
    company has to release it under GPLv2.

> Of
> course that's not an argument to change the license, but I believe it
> also highlights how hard it is to understand the GPL requirements on
> the Buildroot case.

Sorry, but it is very clear to me, and I am no lawyer. And any decent
company will have a rather decent team of lawyers to help in these types
of cases.

> So, I believe that we should either:
> 
>  (1) Clarify and document how we believe the GPL terms apply to
>      Buildroot (this would probably be a long discussion process, in
>      which the SFLC should probably participate). When I see the
>      discussions around BR2_EXTERNAL where the package .mk files and
>      Config.in files may be seen as derivative work, but not the root
>      filesystem overlay, or that package .mk files for GPL packages
>      should be under the GPL,

It all revolves around the definition of a "derivative work".

We have to decide whether BR2_EXTERNAL is, or parts of it are, a derived
work of Buildroot. I think you now know my position, I guess. ;-)

>      but not necessarily .mk files for non-GPL
>      packages,

Wrong. *If* they are distributed, they'll be under the GPLv2.
But since they build proprietary (or weak-copyleft licensed) packages,
it is _not_ required that they be distributed.

>      I believe it is way too complicated for users. To me, it
>      seems like complying with the Buildroot license is more
>      complicated than using Buildroot itself, which is kind of silly.


>  (2) Change the Buildroot license to a non-copyleft license.

That would be a *hard* thing to do, I'm afraid.

>      Of course,
>      that requires contacting a lot of people, but maybe not so much:
>      over the last 3-4 years, the vast majority of the Buildroot code
>      base has been rewritten, and many of the people having worked on
>      that are still around today.
> 
> Thoughts?

I lean toward an explanation in the manual (with proper disclaimer that
entice the user to seek legal counsel).

Regards,
Yann E. MORIN.

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