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Re: linking to GPL'd libraries WAS Re: One unclear point in the Vim license

On Fri, Jan 04, 2002 at 05:22:07PM +1100, Hamish Moffatt wrote:
> For example, the kernel is GPLed but will load and run programs
> with incompatible licenses. Those programs make syscalls to
> the kernel to perform system work; how is this permitted?
> It is so different from an incompatibly-licensed program linking
> to a GPLed library?

And Linus Torvald has added a statement just before the GPL in the file
COPYING at the top level directory of the kernel source tree that makes it
clear that he thinks that user level programs that only use syscalls to
communicate with the kernel are considered to be using the kernel in a
normal way.

> The ldso license is interesting (/usr/doc/ldso/copyright, possibly
> only on potato or earlier systems). The commentary implies that
> ld.so deliberately uses the BSD license because the GPL is too
> strict.

Which means that the GPL serves the purpose it was intended for.
The understanding of the GPL by the ldso author seems to be in line with
what Thomas and many other people say about the effectiveness of the
copyleft in the GPL.

The "general understanding of the [...] contributors" is from that
perspective merely wishful thinking.

> Tcl can dynamically load shared libraries so that scripts can
> use library functions. tcl itself appears to have a BSD-type
> license. What if a tcl script, using a non-GPL compatible
> license, causes tcl to load a GPL library (eg libreadline)?
> The script is being interpreted by the Tcl shell, it's not 
> capable of being linked to anything itself.

It might depend on the way that happens.  If the script is not written in a
way that depends on this behaviour and is in general unaware of that loading
happening, and is not shipped with a version of tcl that loads such a
library, then it might be okay.  The other extreme is that the script
explicitely triggers this loading and depends on this behaviour, and all
three are shipped in one product.  All these details matter, and you will
not be able to get a good answer to an incomplete question in license

> Getting off-topic a bit, there's an interesting clause in the 
> license for libio, in /usr/doc/libc6/copyright (on potato anyway).

Not on woody, and I don't have potato to check the context.  So no comment :)


`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org

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