A question about rtems license

Gedare Bloom gedare at rtems.org
Sat Jul 18 15:49:29 UTC 2020

On Sat, Jul 18, 2020 at 9:20 AM Christian Mauderer <oss at c-mauderer.de> wrote:
> Hello,
> note that I'm not a lawyer. I can only provide my personal opinion
> regarding that topic. Depending of the legal system of your country a
> lawyer might has a different point of view. I'm also only a small part
> of the project and can't speak for all persons involved.
Indeed, we have no lawyers here to provide legal advice.

> As far as I understand your situation you basically forked RTEMS. The
> fork would consist of "rtems src" and "rtems src2". These parts would be
> covered by the RTEMS license. So if you provide a binary to someone, you
> would have to make the "rtems src" and "rtems src2" available to this
> person too if they ask.

Yes, if you modified "rtems src" and then distribute it, you need to
provide the source for those modifications.

> But your application is still a separate part and would be covered by
> the linking exception. That means: you can keep it private.

Also correct.

> Please note that there is an ongoing effort to change the RTEMS license
> to a BSD style license. A lot of sources are already BSD licensed. You
> can see that if you have a look at the file headers.

That said, we encourage users to provide us with the changes they made
to rtems. There are advantages if your changes are accepted, then you
have more confidence about their correctness (additional review) and
they may also be maintained by the community as long as they are

> As another note: RTEMS is always open to patches. So you might want to
> think about polishing the "rtems src2" parts a bit and sending them to
> the mailing list for integration into the official sources.

> Best regards
> Christian
> On 18/07/2020 11:45, smallphd at aliyun.com wrote:
> > Hi,
> > There is a project using rtems as a real time os in an arm cortex R5
> > bsp.  Primary RTEMS License says
> > that RTEMS is free software; you can redistribute it and/or modify it under terms of the
> > GPL.
> > As a special exception, including RTEMS header files in a file, instantiating RTEMS generics or templates, or linking other files with RTEMS objects to produce an executable application, does not by itself cause the resulting executable application to be covered by the GPL.
> > I draw a picture to describe this special exception:
> > There are "rtems src", "rtems header" and our "application".  The "rtems
> > src" will be compiled to a lib called "rtems lib".  If our "application"
> > includes "rtems header" and linkes with "rtems lib", then our
> > "application" does not follow GPL.
> >
> > OK, here is my question: we modify some code in "rtems src" and build it
> > to "rtems lib2".  If our "application" includes "rtems header" and
> > linkes with "rtems lib2", whether or not our "application" should follow
> > GPL?
> > (of course, rtems src2 should follow GPL)
> >
> > ------------------------------------------------------------------------
> > smallphd at aliyun.com
> >
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