bug#26256: [PATCH 5/6] gnu: Add userspace-rcu.

[ludo@gnu.org (Ludovic Courtès)]

Marius Bakke <mbakke@fastmail.com> skribis:

> Sorry for spamming this discussion, but it's something that I haven't
> seen discussed before and it's good to clarify a few of these points.
>
> Ceph is also a prime example of a complex package covering lots of
> licenses. Some of the ".so" files installed by Ceph are produced by
> BSD-style code. However, they link to the main ceph libraries, which are
> LGPL2.1. IIUC, LGPL2.1 "trumps" BSD here because of the strong copyleft.

Right, copyleft licenses “win” over the non-copyleft ones.

> Ceph also installs some erasure code ".so" files that do *not* link
> against Ceph (as verified with readelf and ldd). They are covered by a
> BSD-style license. These should then be mentioned separately, methinks,
> because they are installed by this package and used by some of the
> (L)GPL code.

Yes, that makes sense to me.

> Most of the Python libraries in Ceph are actually LGPL2.1+. These use
> the main Ceph libraries, which are LGPL2.1 (no plus). AFAIU, the latter
> still "wins", or should LGPL2.1+ be mentioned separately?

I’d mention just LGPL2.1 since it “wins” over LGPL2.1+, but with a
comment explaining the situation.

(There’ll be a lot to read in that file! :-))

> Perhaps the manual could be improved with a few clarification points,
> although it's a complex issue that will vary on a case-by-case basis.

Indeed!  We also need clarifications on when to use “+” on GNU licenses,
since it’s never obvious to newcomers.

Thanks,
Ludo’.