Re: GPL issues

["Jesper Juhl" <jesper.juhl@gmail.com>]

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


> (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.


> 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.


> 2. If the application has to be packaged with the
> Linux kernel, example: tarball that includes kernel +
> application, can this application be released without
> GPL. (The changes to Linux kernel are already released
> under GPL).
>
If the application is to be included in the mainline kernel tarball
and distributed from kernel.org, then I would say it would need to be
GPL.
If it's a tarball you provide with a modified kernel with all kernel
modifications released under GPL, then a userspace application bundled
in the tarball would not nessesarily need to be GPL.


> 3. How does this work if this application + kernel has
> to run on a proprietary system on a seperate interface
> card? Can I assume that once there is a clear hardware
> boundary rest of the software for the system does not
> have to be released under GPL? The software for the
> interface card will be built and distributed
> seperately from the rest of the software.
>
> 4. Can the GPL code and non-GPL code exist under the
> same source tree?
>
Not in the mainline kernel.


> 5. In case of litigation, will there be pressure to
> open up other parts of the software (non-GPL) running
> on the same system but on other hardware components
> interacting with this new package on a different
> interface card?
>
No idea.

> Anyone trying to build a new application to work on
> Linux must have these issues clarified, if you can
> share your experiences that would be great too.
>
> Thanks,
> Ram
>


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Jesper Juhl <jesper.juhl@gmail.com>
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