RE: Linux GPL and binary module exception clause?

From: Linus Torvalds
Date: Fri Dec 05 2003 - 14:28:11 EST

On Fri, 5 Dec 2003, Kendall Bennett wrote:
> Right, and by extension of the same argument you cannot use kernel
> headers to create non-GPL'ed binaries that run IN USER SPACE!

This was indeed one of the worries that people had a long time ago, and is
one (but only one) of the reasons for the addition of the clarification to
the COPYING file for the kernel.

So I agree with you from a technical standpoint, and I claim that the
clarification in COPYING about user space usage through normal system
calls covers that special case.

But at the same time I do want to say that I discourage use of the kernel
header files for user programs for _other_ reasons (ie for the last 8
years or so, the suggestion has been to have a separate copy of the header
files for the user space library). But that's due to technical issues
(since I think the language of the COPYING file takes care of all
copyright issues): trying to avoid version dependencies.

> This exact reasoning is what RedHat (aka Cygnus) has been using for years
> with the Cygwin toolkit for Windows. Although 99% of the code built with
> the GNU compilers and Cygwin includes the glibc runtime library that is
> LGPL, every program *must* include the C runtime library startup code or
> it cannot function. *That* code is pure GPL, and by extension any program
> using the Cygwin libraries is a derived work and must be GPL. If you
> don't like that, by a commercially licensed version of Cygwin from
> RedHat/Cygnus instead.

And this is an area where I think the GPL just isn't the right license to
use - but on the other hand it obviously isn't my decision to make. I'm
not touching Cygwin with a ten-foot pole, and that has nothing to do with
licensing ;)

The GPL just doesn't make a lot of sense for library-like infrastructure.

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