Re: [PanoTools-devel] Licensing...Re: New projection: Miller

[JD S. <jd...@as...>]

On Mon, 29 Jan 2007 23:58:21 +0100, Erik Krause wrote:

> On Monday, January 29, 2007 at 14:08, JD Smith wrote:
> 
>> > Only for curiosity and because no one answered the question last time
>> > I asked it: According to http://en.wikipedia.org/wiki/Linux_kernel
>> > Linux is licensed under GPL. As far as I know there are Linux closed
>> > source programs. Are they allowed to link to Linux kernel routines or
>> > are they not?
>> 
>> They are, by a special allowance (not a modification to the license).
>> 
>> E.g. linux/COPYING says: This copyright does *not* cover user programs
>> that use kernel services by normal system calls - this is merely
>> considered normal use of the kernel, and does *not* fall under the
>> heading of "derived work".
> 
> But this shows that the GPL alone is not clear in this point. If an
> allowance is possible without infringing the license, then the license is
> not strict and can be used this or that way.

The only issue is what constitutes a "derived work", and it's an issue not
specific to the GPL, but for copyright law, generically. 

Different people have different opinions (for instance, the FSF treads
very lightly around this notion of proprietary plug-ins). In the end,
courts decide case by case.  They often look at whether something made
substantial use of the original program.  To me, writing a userland
application that happens to call a Linux kernel function via the
normal API seems worlds apart from writing a front-end to a library
which contains most of the algorithms required for your program to
function.

The original context of this discussion was the GSL, a GNU library for
scientific calculations.  The GSL maintainers are quite explicit about
the permitted uses of their library, and the current PanoTools
situation would not work for them, I'd guess.  Here's an example:

  http://sourceware.org/ml/gsl-discuss/2001/msg00390.html

The FSF likewise is quite explicit about what constitutes derivative
works: anything that runs library code in the same process space (and
eventually more; in GPL3, you can't hide behind offering an
application as a web service).  See:

  http://www.gnu.org/licenses/why-not-lgpl.html

> This at least would make allowances possible for the plugins. And perhaps
> it would make well defined allowances possible for other closed source
> programs, too. Especially since the past policy (which was encouraged by
> Helmut!) established something like a customary right.

Can you shed more light on what encouragement Helmut gave to the
front-end tools, if any?  It would be useful to know his stance in
detail.

JD