[IGSTK-Developers] RTLinux Licensing

[Luis Ibanez]

Hi Patrick,


        GPL is OK for operating systems.


   * Your current Linux operating system is GPL.

   * Your current Cygwin is GPL too.


----


The Linux community does not consider your applications
running on a GPL operating system to be derivative work.


A good discussion on the use of GPL software for embeded
application can be found in linuxdevices.com:

http://www.linuxdevices.com/articles/AT9161119242.html

of particular interest is the classification
of five categories of software:

1) User-space applications running under Linux
2) Loadable device drivers using the normal kernel interfaces
3) Loadable modules using non-standard kernel interfaces
4) Standalone kernel modules
5) Modifications to Linux itself


IGSTK is typically in (1), but if we move into using RTLinux
for IGSTK-RT, then our IGSTK classes will be loaded as modules,
which put them in (2).

RTLinux is basically a modified Linux Kernel, where the
scheduler has been replaced, and it takes the rest of the
normal Linux kernel and runs it as an "application" in
the form of a "service" class.

It is questionable, whether our IGSTK modules would be in
category (3), since after all, they are connecting to a
modified Kernel.


----

That being sais, RTLinux has received a lot of
controversy because the system itself may be
violating the GPL License of the non-real-time
Linux system. The reason is that Victor Yodaiken,
obtained a patent on a variation of the Linux
Kernel. This variation is a key element on the
way RTLinux manage prioritized interruptions.


Filing for a Patent, over a variation of a GPL
software is considered to be a violation of the
license, or at least of the spirit of the GPL
license as the Free Software Foundation sees it.

In plain english, somebody takes free software,
makes a variation of it (derivative work) and
applies for a patent on the variation.

Yodaiken claims that the purpose of the patent
is to prevent others for patenting the same
idea and limiting its use to the Open Source
community. He also claims that it is very unlikely
that the patent will be enforced, which from
the legal point of view is an irrelevant claim,
since he or his company could change their mind
with the next change in their manager's positions.

FSMLabs and the FSF seems to have worked out the
details with a second version of an "Open Patent
License"

http://www.gnu.org/philosophy/rtlinux-patent.html

 > The Free Software Foundation and Finite State Machine Labs Inc.
 > (FSMLabs) today announced the release of the Open RTLinux patent
 > license Version 2 fully compliant with the Free Software Foundation's
 > GNU General Public License (GNU GPL). The Open Patent License grants
 > the right to use U.S. Patent No. 5,995,745 in GPL-covered free
 > software without payment of a royalty. This license protects GPL use
 > of the RTLinux process.
 >

and the two organization are in friendly terms now.



....


In any case, that does not afect IGSTK-RT since
our application will be running as tasks on top
of the operating system.

I would be an issue if we were changing the RTLinux
Kernel in order to make IGSTK work.

... it will be the same issue if we were changing
     the normal Linux kernel...


For more details on licensing, please look at the
NAMIC page on licensing discussions,

http://www.na-mic.org/Wiki/index.php/NAMIC_Wiki:Community_Licensing

and take a look a Lawrence Rosen book

"Open Source Licensing:
  Software Freedom and Intellectual Property Law"

for free online at:
http://www.rosenlaw.com/oslbook.htm

or from Amazon at:
http://www.amazon.com/exec/obidos/tg/detail/-/0131487876/ref=wl_it_dp/102-3709525-0890551?%5Fencoding=UTF8&coliid=I2R16UMOBGUB0Q&v=glance&colid=Y33DWL1PUGRV


   Luis



-------------------
Patrick Cheng wrote:

 > The RTLinux comes with GPL license. Does the real-time igstk count 
for a derivative work?
 >
 > You must read and accept the terms of both the GPL Version 2.0 and 
the RTLinux Open Patent License Version 2.0 to download this. Both 
licenses can be found on this site using search.
 >
 > Patrick