[ Thanks to Jeremy
Andrews for this link. ]
“When first made available in September of 1991, the Linux
kernel source code was released under a very restrictive non-GPL
license requiring that the source code must always be available,
and that no money could be made off of it. Several months later
Linus changed the copyright to the GPL, or GNU General Public
License, under which the kernel source code has remained ever
since. Thanks to the GPL, any source code derived from the Linux
kernel source code must also be freely released under the GPL. This
has led many to question the legality of ‘binary only’ kernel
modules, for which no source code is released. Linux creator Linus
Torvalds talks about this issue in a recent thread on the lkml
explaining:“‘But one gray area in particular is something like a driver
that was originally written for another operating system (ie
clearly not a derived work of Linux in origin). At exactly what
point does it become a derived work of the kernel (and thus fall
under the GPL)? THAT is a gray area, and _that_ is the area where I
personally believe that some modules may be considered to not be
derived works simply because they weren’t designed for Linux and
don’t depend on any special Linux behaviour…'”