Custom platform for commercial device

[Russell King - ARM Linux]

On Tue, Aug 07, 2012 at 05:56:46PM +0200, Gaëtan Carlier wrote:
> Hello,
> I have license related questions :

You should ask your solicitor these questions.

**** DISCLAIMER ****
What is below is my understanding of the GPL license, which is the
only license which allows you to make use of the Linux kernel - which
includes a substantial amount of code authored by myself.

> 1) if I create and sell a device which is a fork of an existing  
> platform, should I have to publish code of this new platform and/or give  
> the code to customer if he asks it ?

The GPL gives you essentially two options - one of them is that you
supply your products with a copy of the _full_ machine-readable source
code which was used to generate the GPL licensed executables.  See 3(a).

The second option is that you provide a written offer of the source
code to anyone who buys your product.  You must supply a copy of the
source to anyone who has bought your product within three years of
that purchase taking place.  See 3(b).

3(c) also comes into play if you decide to go down this route, because
it's not only your direct customers who can request a copy of the source,
it's anyone who _they_ have passed your product or the binaries in your
product to.  So the effect of 3(b) + 3(c) is that you have to supply
anyone who requests a copy of the source with it.

> 2) Should I have to mention that my device is powered by Linux kernel ?
> For a PC software, the GPL must be displayed at installation time but  
> for embedded devices (ie. if a closed source software is used to send  
> new kernel to the device) ?

2(c) comes into play for this.  I believe the Linux kernel not to be an
interactive program (it isn't gdb.)  Therefore, it doesn't display a
GPL notice at startup, and therefore there's no need for it to display
such a notice at boot time.

It would be nice if manufacturers would credit where they got a
substantial amount of code from in their products, whether it be in a
manual or something, but the GPL does not explicitly require it.

Note that what you aren't able to do is to remove or prevent any GPL'd
program which already displays its license from doing so when
incorporating it in a product.

> 3) Can I send patches to this list to add this new platform to be able  
> maintain it more easily when kernel change implementation of some drivers 
> ?

We always encourage that, provided the code isn't just "chucked over the
wall" at us.  In other words, we'd like any code that makes its way into
the kernel to be maintained and used.  Otherwise, it becomes a maintenance
burden, and will eventually be removed.

And here's a reminder of the disclaimer:
**** DISCLAIMER ****
What is above is my understanding of the GPL license, which is the
only license which allows you to make use of the Linux kernel - which
includes a substantial amount of code authored by myself.