LGPL library using only LGPL-parts of partially GPL shared library (gnutls, nettle)

Simon Josefsson simon at josefsson.org
Sun Feb 20 17:33:45 CET 2011

Andreas Metzler <ametzler at downhill.at.eu.org> writes:

> On 2011-02-20 Simon Josefsson <simon at josefsson.org> wrote:
>> Andreas Metzler <ametzler at downhill.at.eu.org> writes:
> [...]
>> > I have the feeling that the discussion I started is an academic one
>> > anyway. Nettle's public key library (libhogweed) uses and links against
>> > libgmp, which is LGPLv3+. Therefore switching gnutls from gcrypt to
>> > nettle would break GPLv2-compatibility (GPLv2 without the "or any
>> > later version " clause). Oh dear.
>> It has been discussed to dual-license some libraries under
>> GPLv2+/LGPLv3+ to avoid this problem.  I wonder if this could be a way
>> out here.  GnuTLS 2.12 is not released (and there is not even any
>> release candidates), so we still have time to resolve this in a good
>> way.
> [...]
> Hello,
> Afaik there is nothing GnuTLS can do. It is using the most permissive
> license of the involved packages. The culprit is the combination of
> third party (L)GPL-v2only software (e.g. cups) with libgmp, which
> switched from LGPLv2+ to LGPLv3+ in 4.2.2.

The FSF has clarified that to resolve that problem, it is recommended to
dual-license projects under GPLv2+/LGPLv3+ see:


So if GMP follows this suggestion, the problem would be resolved for
GPLv2-only projects.  Did you really notice any LGPLv2-only projects
using GnuTLS when you looked?


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