[linux-elitists] questions about GPL again

Greg KH greg at kroah.com
Fri Mar 9 07:34:15 PST 2012

On Fri, Mar 09, 2012 at 04:19:07PM +0100, Eugen Leitl wrote:
> On Fri, Mar 09, 2012 at 06:59:07AM -0800, Greg KH wrote:
> > On Fri, Mar 09, 2012 at 12:02:03PM +0100, Eugen Leitl wrote:
> > > 
> > > A senior guy from a rather well-known chemical abstracs service
> > > just made the claim that GPL is contagious even for dynamically linked
> > > code. Which I recall as not being correct.
> > 
> > What do you mean by "contagious"?  And which version of the GPL are you
> In the corporate wonk oh-noes-we-have-to-opensource-everything-touched-by-GPL
> sense.

That baseless rumor is still spreading around?  Please just ask anyone
who is making such a statement to show the relevant part of the GPL
itself that says that.

> > referring to?
> They cluster v1/v2/v3 as one for all practical purposes. Is the
> dynamic-linking of GPL libraries by proprietary code treated
> differently across v1 to v3? 

There really isn't any v1 code anywhere in the world, so don't ever
worry about that.

And if you are referring to libraries, don't you mean LGPL?  That's
usually the license for them (with some well known exceptions, i.e.

The simple answer is, if you dynamically link in GPL code (note, not
LGPL) with your propritary application, you just violated the license of
the library.  It's really that simple.

As for the "penalty" of what then happens, that's not defined in the
license, it's up to a judge to decide that.  Perhaps a judge would
require the release of the propritary code, but that's highly unlikely.
What's more likely is lots of money would exchange hands, probably more
than would have cost to just write the library from scratch in the first

If someone is worried about what happens "when we get caught" that
implies that they know they are doing something wrong, and shouldn't be
doing it in the first place.

> > > Can somebody point me towards a definitive document or
> > > piece of writing by a lawyer which definitevely shows
> > > what the actual situation is?
> > 
> > The GPL itself is very easy to read, have you tried that?
> Apparently (according to many online writing) many people 
> find it confusing enough that they think ability to dynamically 
> link (=just call a GPL library) requires a lawyer to interpret
> how things are in your jurisdiction. 
> I'd rather like to be able to cut through the FUD authoritatively. Is there
> anything specific e.g. written by Eben Moglen I could point poor confused
> souls to?

Again, I gave the "simple" answer above.  There are ways of doing this
that do not violate the GPL of the library (I have a program out there
myself that does it as an example), but that gets into specific
semantics, and the definition of derivitve works and other fun things
like that.

The easy thing to always respond to questions like this is, "If you are
trying to do this, you need to be talking to a lawyer.  If you can't
afford a lawyer, then you better just release your code under the GPL as
you don't have anything to worry about then, and you really aren't

That's the easiest way to cut through any FUD.  Because, would you take
medical advice from a programmer?  No, then why would you take legal
advice from one?

Good luck,

greg k-h

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