Re: GPL issues

Horst von Brand
2006-04-11T17:46:41Z

Jesper Juhl <jesper.juhl@gmail.com> wrote:
> On 4/11/06, Ramakanth Gunuganti <rgunugan@yahoo.com> wrote:
> > I am trying to understand the GPL boundaries for
> > Linux, any clarification provided on the following
> > issues below would be great:
> >
> > As part of a project, I would like to extend the Linux
> > kernel to support some additional features needed for
> > the project, the changes will include:
> > o Modification to Linux kernel.
> > o Adding new kernel modules.
> > o New system calls/IOCTLs to use the kernel
> > modifications/LKMs.
> >
> > All kernel changes including LKMs will be released
> > under GPL.
> >
> > Questions:

> Note: The answers to the questions below are based on my own personal
> understanding of the GPL and the policies of the Linux kernel.

IANAL either.

> Also contacting a lawyer would probably not be a bad idea.

Essential, not just a good idea. Just pick one who /does/ have a grasp of
GPL and like issues.

> > (Any reference to GPL license while answering these
> > questions would be great)
> >
> > 1. If an application is built on top of this modified
> > kernel, should the application be released under GPL?
>
> No. Applications that merely use the services the kernel provides need
> not be GPL.

But AFAIU there is a fine line here... at least /in spirit/, adding system
calls and IOCTLs and... just for the particular use of a particular closed
source application is definitely wrong. It might be legally OK (I don't
know; the opinion here is divided on that kind of matter, see f.ex. the
regularly scheduled flamefest about binary modules), but morally it is at
least suspicious.

> > Do system calls provide a bounday for GPL? How does
> > this work with LKMs, all the code for LKMs will be
> > released but would a userspace application using the
> > LKMs choose not to use GPL?

> Again, a userspace application that merely use kernel services need not
> be GPL.

As long as it uses the standard system calls. Adding special system calls
might (should?) change that...
--
Dr. Horst H. von Brand User #22616 counter.li.org
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