Re: Linux in a binary world... a doomsday scenario

Tim Bird
2005-12-06T01:20:34Z

Andrea Arcangeli wrote:
> On Mon, Dec 05, 2005 at 03:56:06PM -0800, Tim Bird wrote:
>
>>If the GPL covers interface linkages (whether static or
>>dynamic) then EXPORT_SYMBOL_GPL is redundant. If it does
>>not, in all cases, then EXPORT_SYMBOL_GPL is, as
>>an extension to GPL, therefore a GPL violation.
>
> The last time I spoke with Linus about this, what I understood can be
> described in two points:
>
> 1) EXPORT_SYMBOL_GPL is an hint: if you have to circumvent it, there are
> high chances that you're creating a derivative of the linux kernel and
> in turn there are high chances that you're illegal
>
> 2) The fact you're illegal or not, has nothing to do with the _GPL tag
> in the exports, the illegal usage is when the module create a derivative
> of the linux kernel.
>
> Now I don't know for sure myself (I'm not a lawyer) what is a derivative
> of the linux kernel (don't ask me), but the two above points are quite
> clear to me.

This interpretation puts kernel developers in the
position of making the legal decision about which
interfaces cause derivate-work risk and which
do not. That's hardly a recipe for legal clarity.
(Not that legal clarity is a goal of Linux
kernel development... :-)
Different developers are likely to have
different viewpoints on which interfaces pose risks.
I guess Linus gets the last call (as usual),
so there's some possibility of some amount
of uniformity here.

Most kernel developers will naturally tend
towards making more symbols EXPORT_SYMBOL_GPL,
whether there's valid legal basis for it or not.
(Please let me know if there's a lawyer somewhere
reviewing the insertion of EXPORT_SYMBOL_GPLs)
David currently suggests that *all* interfaces
be so designated. I suspect he strongly believes
that any use of a kernel interface creates a
derivative work. I have a different opinion.

...

> The _GPL tag is useful as an hint to binary only vendors as as such it
> makes perfect sense.
Well, if it makes sense to have developers giving out legal
advice, then I guess so.

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================