The problem with this position is...

Posted Dec 18, 2006 11:43 UTC (Mon) by hummassa (subscriber, #307) [Link]

And, as English is not my mother tongue, I'll try to sum it up
(apologizing for the loooong post):

Initially, coriordan has said: """The idea of making the kernel refuse to
load the drivers has been withdrawn, but maybe another solution is
possible such as publicly stating that proprietary drivers are derived
works, and giving the public 12 months prior warning of this position.

Linus has said that he doesn't like copyright law stretching that way, but
he also seems open to being convinced that copyright law does stretch that
way, and that it's useful that it stretches that way"""

In fewer words: "I suggest kernel developers make a joint statement saying
that they consider anything linking to the kernel or loaded in kernelspace
as a derivative work of Linux"

And I responded to it: """copyright law does not stretch that way.
Derivative works, as I have stated many times, are those selected by the
test "abstraction, filtration, comparison". If you say "I'm licensing this
under the GPL but I consider any linking object's source as a derivative
work" you are adding a restriction over the GPL terms (*), and the GPL
forbids that (in section 6: "You may not impose any further restrictions
on the recipients' exercise of the rights granted herein")."""

In (not really) fewer words: "they cannot do that, because [1] they can't
redefine what is or is not a derivative work and [2] if they do (in the
context of the kernel license) the kernel becomes undistributable because
it will be licensed GPLv2 + additional restriction (considering things
that are _not_ derivative works as if they were)"

You: "Since when is kernel development motivated solely by copyright law?"

I did not respond -- it never was motivated by copyright law, but GPL_ONLY
symbols are a clever hack that make _use_ of copyright law.

You: "Are GPL_ONLY symbols governed by copyright law?"

Me: """GPL_ONLY symbols are AFAICT a "declaration of intent". They mean
"if you link to this symbol, then we (the kernel developers in genereal)
think you are thinkering too deep with the linux internals, so your
module OUGHT to be a derivative work of the kernel (and consequentially
must be licensed under terms compatible with the GPLv2)."""

I.e., the GPL_SYMBOLS in the kernel are similar to the Copyright (C)
assingments: they are declarations contained in the text of the kernel,
for copyright law purposes.

You: "I would assume they aren't, since they change over time while the
law (and the international treaties it is based upon) remains the same"

They change over time because the definition that the kernel developers
have of "this and this symbols are part of an intimate part of the kernel,
so if people use this they are probably developing a derivative work"
change. But this has nothing to do with changing the copyright law. It's
more akin to re-licensing a part of the kernel.

In the parent post, you said: """Where is copyright law in that
"declaration of intent"? Where is "abstraction, filtration,
comparison"?"""

I hope I have stated clearly that the GPL_ONLY symbol declaration is for
_purposes_ of copyright, exactly to give _some_ clue for the people that
are applying "abstraction, filtration, comparison" over the kernel that
things that use those symbols probably should _not_ be filtered. That is
AFAIK (and I know a little bit about this) the extent of the GPL_ONLY
declarations.

Instead of writing:
EXPORT_SYMBOL_GPL(cascade_irq);

The kernel developer could have written:
/* Copyright (C) Copyright (C) 2005 Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
** CAVEAT EMPTOR:
** If you use the symbol cascade_irq, then you are probably making a
** derivative work of this file. If this is the case, you must license
** your work under the GPL if you ever distribute it. */

Things above have the exact same legal value AFAICT.

Now, you raised the DMCA thing: """Note that the GPL_ONLY mechanism
doesn't just display a warning (as would be expected from a "declaration
of intent"); it effectively prevents your use of the symbol at runtime,
and therefore it might be argued that it constitutes an "effective
protection measure" against copyright violations, as stated in the DMCA
and the equivalent EU directive. Spooky."""

To this, I have to comment:

1. The DMCA is not only spooky, but downright evil.

2. Notwithstanding that, the GPL_ONLY symbols as "effective measure" would
not fly, because it is enough that you declare your module as GPL falsely
to the the GPL_ONLY mechanism (remember the "GPL\0 something else" trick?)
or that you compile a kernel where the GPL_ONLY mechanism is disabled.

2a. Notice that a kernel where the GPL_ONLY mechanism is disabled is a
valid, legal derivative work of the kernel ... as long as it is
distributed under the terms of the GPLv2. _NOTHING_ (legal) stops a distro
from distributing such a kernel. They just don't because it's easier for
support purposes to know if there is a non-GPLd module tainting the
kernel...

2b. Notice further, that as the kernel (via GPLv2) expressely allows for
the licensee to make any kind of derivative work (modulo the exceptions on
the GPL section [2]) including those circumventing GPL_ONLY restrictions,
this is /de/ /facto/ a waiver on the "effective measures" thing.