LWN: Comments on "Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]"

Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]

dwpfitzner — Fri, 22 Dec 2006 02:44:05 +0000

No, as I understand it, the GPL does not define what is a derivative work -- copyright law does. Put another way: the GPL considers something a derivative work if it is a derivative work under copyright law. That is why there is a grey area: the definition of derivative work under copyright law is a grey area.

Eg, from GPL v2, section 0:

... a "work based on the Program" means either the Program or any derivative work under copyright law

Actually it goes on to say a bit more:

... a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".)

so it sort of includes a definition, but not being a lawyer I'm not sure how much weight the "that is to say" part has.

Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]

orospakr — Fri, 15 Dec 2006 14:29:14 +0000

From what I understand, the GPL considers something a derivative work if you either modify distribute a *changed* version of the work, OR you distribute something that links against the work's interfaces (#including header files, etc.).

nVidia wrote their driver in such a way as to avoid these restrictions (whether or not this is technically true is debatable, I suppose). The proprietary piece of their kernel module is wrapped entirely in Free Software code, and thus the proprietary piece does not derive directly from Linux itself. There's a technical reason for this, too: Linux will not load modules that weren't compiled against the *exact* same headers with the same gcc options, etc., so the Free Software piece provides a level of indirection for the kernel-agnostic proprietary piece. When faced with a kernel it has never seen before, the nvidia installer just compiles a new module provided the kernel api hasn't changed too much.

(The same thing applies to the Atheros HAL)

Do I have all that right?

Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]

ebiederm — Fri, 15 Dec 2006 02:55:22 +0000

Basically the argument is that if something is written for another OS first, and then trivially ported to linux it is very hard to make the arugment that the other piece of code is a derived work. If a piece of code is not a derived work how can the GPL apply?

The grey area comes from the question: How much do you need to modify your
preexisting code to make it a derived work?

Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]

russell — Thu, 14 Dec 2006 23:00:07 +0000

How is this a "gray area"? I've never heard a good argument for it being gray. Does anyone have some links to the argument? I presume Linus has explained this elsewhere. Are there any judgements in this area?

Personal copy

corbet — Thu, 14 Dec 2006 22:11:27 +0000

I had jumped into the discussion earlier in the thread, and so became part of the cc list - nothing more than that.

Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches for 2.6.19]

ernest — Thu, 14 Dec 2006 20:52:52 +0000

Interesting to notice that apparently My Editor get his own very personal ccopy of that email.