Have you stopped to consider that it is the GPL that is incompatible with the other licenses, not the other way around?

Apologies for sounding pedantic here, but this is incorrect. The GPL cannot be incompatable with the CDDL and MPL without the MPL and CDDL being incompatable with it. It's obviously silly to describe one as incompatable with the other but not the other way around. The MPL and CDDL most certainly are incompatable with the GPL.

If you badly worded the above, and meant the emphasis should be on the GPL in terms of where the problems are coming, my entire posting addresses that: The GPL is neutral, it requires the imposition of no further restrictions, and therefore is one of the few players in town that qualifies as a legitimate baseline FOSS license for licenses to aspire compability with. The same is not true of the CDDL, MPL, or non-copyleft licenses such as the BSD and X11 licenses. The former are not project neutral. The latter do not prevent more conditions being attached, which essentially makes them useless from an interoperability point of view.

For example, you can mix and match code from CDDL, BSD and MPL all you want, there are no restrictions in that regard.

No, you can't.

The MPL is not compatable with the CDDL and vice versa. You cannot use code from an MPL project in a CDDL project. In fact, the licenses get legally problematic even when you try to combine code licensed under the same license from two different projects sourced by two different "Initial Developers". So not only is the MPL and CDDL incompatable with the GPL and each other, but frequently not even themselves!

When you throw GPL in, you have to license the entire kit and kaboodle under GPL.

There really isn't a lot of difference in the case of the MPL and CDDL. Both require that any relicensing be done under a license that imposes the same restrictions and grants. Essentially they're saying "You can relicense this under any license you want, as long as it's this one, or a rewrite." Most additional rights granted are, in any case, a re-statement of copyright law.

The real problem with both is that both try to elevate the initial developer to a special status. While it might be understandable, it's by design going to create problems getting multiple projects to cooperate. As soon as you say "This license does something special if {something that's project specific}", then you're into incompatable licenses.

Example - a company works with an OSS project and contributes code back on a regular basis. They have an opportunity to provide the project with support for a new deice, but the information they can do this with is covered under an agreement that prevents them releasing the code for this device. Under BSD or CDDL, no problem, they are not required to provide the code. Under the GPL, they cannot do this - development is stifled. Of course, the root of the problem is the locking down of the required information - but often we are talking buisness and competition issues i.e the real world.

In the situation you describe, the "fault" doesn't lie with the GPL. There's nothing stopping the developers - as a group, all of them who have contributed code - from saying "Yes, we'll do this closed source thing for this particular module", because the developers own the copyrights, and can agree, as a group, to dual license. This, of course, doesn't mean the developers will, it may be - shock horror - that the developers are opposed to their work being used in proprietary code, which leaves the company that wants to restrict the information used for the device driver the major stumbling block.

The CDDL, incidentally, doesn't allow this any more than the GPL does with the possible exception (and the CDDL is actually vague here, which makes matters worse) of the "initial developer" who gets some special rights. Both the MPL and CDDL are so-called "weak

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