A discussion on combining CDDL and GPL code

Posted May 26, 2016 11:35 UTC (Thu) by HsuYun (guest, #108980)
In reply to: A discussion on combining CDDL and GPL code by mirabilos
Parent article: A discussion on combining CDDL and GPL code

Maybe I'm missing something here, but I also don't understand why Canonicals distribution of the ZFS module violates the GPL, although for different reasons:
- The CDDL says (at least that's how I understood the article) that the executable produced from the source can be re-licensed under any license you like. "You" in this case is Canonical, so they could simply re-license the binary .ko file under the GPL
- The GPL says that if binary modules are distributed together with the kernel binary, the binary modules must also be licensed under a compatible license, not just the source of the modules.
- The binary ZFS module built from the ZFS sources by Canonical and licensed under the GPL can not be re-licensed by someone else to a license incompatible with the GPL.
Where is the conflict? Could someone please enlighten me?

A discussion on combining CDDL and GPL code

Posted May 26, 2016 17:25 UTC (Thu) by pboddie (guest, #50784) [Link] (4 responses)

- The CDDL says (at least that's how I understood the article) that the executable produced from the source can be re-licensed under any license you like. "You" in this case is Canonical, so they could simply re-license the binary .ko file under the GPL

- The GPL says that if binary modules are distributed together with the kernel binary, the binary modules must also be licensed under a compatible license, not just the source of the modules.

Right. But the article points out that the source code must be distributed only under the terms of the CDDL. So, any attempt to distribute a binary under the terms of the GPL will end up violating the GPL because the source code would then only be offered under the terms of the CDDL, and the CDDL is not GPL-compatible.

A discussion on combining CDDL and GPL code

Posted May 26, 2016 23:12 UTC (Thu) by Wol (subscriber, #4433) [Link] (1 responses)

> So, any attempt to distribute a binary under the terms of the GPL will end up violating the GPL

Not necessarily. Who owns the copyright in the binary? If they place the binary under the GPL, then they can't be sued for violating the GPL, and anybody who receives the binary under the GPL can presumably distribute it under the GPL.

After all, what does "the preferred form for modification" mean? If all you've got is the binary, then it's the *only* form for modification, so "preferred" is meaningless ...

Weird result, I know, but licences don't apply to copyright holders. Too many people forget this. And when you start mixing rights, you can end up with weird combinations.

Cheers,
Wol

A discussion on combining CDDL and GPL code

Posted May 27, 2016 13:12 UTC (Fri) by pboddie (guest, #50784) [Link]

Not necessarily. Who owns the copyright in the binary?

Presumably it is the copyright holder. Otherwise, "anything goes" and the consequences would be very broad indeed. For example, you could machine-translate Harry Potter, sell copies, and not get sued by its apparently-already-litigious author.

If they place the binary under the GPL, then they can't be sued for violating the GPL, and anybody who receives the binary under the GPL can presumably distribute it under the GPL.

I don't think that "place the binary under the GPL" makes any sense whatsoever given that the act of distribution is governed by source code distribution provisions in the GPL. In effect, "I don't have the sources, so it's OK" is making a promise you can't keep.

Now, it might be the case that someone could take a permissively-licensed work, play the "place the binary under the GPL" game, then claim that they aren't obliged to provide the source, and state that they haven't violated the licence imposed by the copyright holder and have therefore not infringed any copyrights. That would be a misuse of the GPL, but I don't know what sanctions might be imposed on someone doing such a thing. Maybe something outside of plain copyright law would apply.

A discussion on combining CDDL and GPL code

Posted May 30, 2016 21:02 UTC (Mon) by HsuYun (guest, #108980) [Link] (1 responses)

Well, then use the MIT license for the binary. I still don't really get the problem. The GPL requires you to license both the code and binary of kernel modules to be under a compatible license. The only incompatibility of the CDDL is that you _could_ license the binary under a non-free license, but if you don't do that, you actually _do_ fulfill the requirements of the GPL that you can do everything with the module you could do with a GPL licensed module. Thinking about it this way, why is it ok to distribute an MIT licensed module with the kernel, because the MIT license would also allow you to license the binary under a non-free license. Where is the flaw in my thinking here?

A discussion on combining CDDL and GPL code

Posted May 30, 2016 21:56 UTC (Mon) by MattJD (subscriber, #91390) [Link]

That's not quite right, the GPL requires the entire worked to be licensed under the terms of the GPL. However, it is believed that the terms of the CDDL and the GPL are not compatible (not that the CDDL allows more, but that it has restrictions the GPL does not), and thus you can't distribute something under both licenses.

The MIT license is fine, because it allows you to distribute under basically any license (it's only restriction is basically a disclaimer, which the GPL shares in spirit (if not text), and thus imposes no further restrictions). Thus you can distribute something under the MIT license as GPL.

In both cases, what matters is that the non-GPL license imposes no more restrictions on the combined work. CDDL does, MIT doesn't.

Note: This is true for the GPL2 with Linux. Apparently the GPL3 is a little more muddy, but for the CDDL is still basically right.

A discussion on combining CDDL and GPL code

Posted May 26, 2016 23:46 UTC (Thu) by anselm (subscriber, #2796) [Link] (3 responses)

The GPL stipulates that if you distribute a binary under the GPL then you must supply the corresponding source code under the GPL. If that source code says that it can only be distributed under the CDDL then you have a problem right there.

A discussion on combining CDDL and GPL code

Posted May 27, 2016 2:18 UTC (Fri) by sfeam (subscriber, #2841) [Link] (2 responses)

Haven't we been around this barn before, and before that, and before that... The GPL can say whatever it likes, but what it says is only relevant to derivative works. Co-distribution of unlinked binaries may or may not create a derivative work, but that judgment is independent of anything the GPL says.

A discussion on combining CDDL and GPL code

Posted May 27, 2016 9:34 UTC (Fri) by anselm (subscriber, #2796) [Link] (1 responses)

We're talking about the binary ZFS module on its own here (as per the previous poster). Even if the CDDL says that it can be distributed under the GPL, the GPL says that binaries must have source code under the GPL (or a GPL-compatible license, i.e., not the CDDL). Derivative works don't enter the discussion.

A discussion on combining CDDL and GPL code

Posted Jun 1, 2016 11:06 UTC (Wed) by nye (subscriber, #51576) [Link]

>We're talking about the binary ZFS module on its own here (as per the previous poster). Even if the CDDL says that it can be distributed under the GPL, the GPL says that binaries must have source code under the GPL (or a GPL-compatible license, i.e., not the CDDL). Derivative works don't enter the discussion

Derivative works don't merely enter the discussion; they *are* the discussion. The GPL can say whatever it likes, but nothing in it can possibly apply to something that is not a derivative work.