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Hi!

On Mon, May 05, 2008 at 10:03:43PM +0800, kevin wrote:
>> On Mon, May 05, 2008 at 10:01:28AM +0800, hlwhyw@shtel.net.cn wrote:
>>>Can I port 4.4BSD-Lite's TCP/IP protocol stack
>>>soure code to my own OS kernel which is GPL
>>>Licence?

>>>I know that 4.4BSD-Lite is BSD Licenced. Is it
>>>legal to port BSD Licenced code and change it to
>>>GPL licence?

>> As Theo de Raadt already wrote, you may not change the license of BSD
>> licensed code. However, the BSD license is compatible to the GPL in the
>> sense that you can combine it with GPLed code with no real hassles.

>> If you have to change the BSD licensed code in a trivial way to port it
>> to your kernel, it remains BSD licensed. If you have to change it in a
>> non-trivial, copyrightable way, you can license your *changes* the way
>> you like (e.g. under the GPL if you choose so).

>Thanks.
>So I can do it in this way:
>Modify the BSD's TCP/IP source code trivialy and keep it BSD licensed as it was.
>Compile it with other GPLed kernel source code.
>Release the binary kernel and all BSDed and GPLed source codes.
>I won't be in trouble. Is it right?

I am not a lawyer, but I think this should work.

You fulfill the BSD license by keeping the copyright notice and the BSD
license intact on the BSD licensed source files which you redistribute.
The BSD license allows you to redistribute the code, in source and
binary form, unmodified or modified (you modify it a little bit to port
it). So I think there should be no problem from the BSD side.

If the GPL sources are yours, there is no problem anyway, as you may do
anything you want with your own work. If there's 3rd party GPL code
involved, you are, of course, bound by the GPL on that code. According
to no. 1 of the GPL you must keep the copyright and GPL license notices
on that code intact as you redistribute the source, and you may charge
no fee for the code itself (you *may* charge for the act of transferring
the code or if you offer additional warranties on your own). As you
modify the work (you add additional code and combine it), you must also
fulfill no. 2.: a says if you modify the GPL sources (e.g. in order to
link in the BSD TCP/IP stack), you most make change notices. b says you
must cause the *whole* work be licenced free of charge (works, as the
BSD license *is* free of charge. The whole work doesn't need to be GPL,
just compatible to those terms of the GPL, and the BSD license *is*
deemed to be compatible nowadays). Then, look at c on your own...

As you also distribute binaries, no. 3 applies too. Your choice seems to
be "a" (you choose to distribute source along with binaries).
So that works too.

Again, IANAL.

Kind regards,

Hannah.