[p_l]

The incompatibility comes from GPL side terms. As for it being intentional, there are only anecdotes, and conflicting ones. When first CDDL sources dropped (DTrace) management expected to see it incorporated into Linux within month

[tylerl]

Thing is, the copyright is owned by Oracle of all companies and and the legality is more than questionable enough to allow Oracle to sue for damages the second the code shows up in use by a big enough fish.

Oracle won't relicense the code (and lose out on a chance at another software copyright lawsuit), and it won't ever be safe to touch without an ironclad licensing story.

You can hope that Oracle folds and gets bought by someone decent. But hope won't take you that far.

Throw it away. Start over from scratch. The code may be great, but it's gone. It's a shame it ended up where it did. Take a moment if you need, but then move on. ZFS isn't going to happen.

[p_l]

Except Oracle isn't the copyright holder for majority of the code, as in fact, it cannot relicense huge chunks of OpenZFS code (which indeed is used in big commercial products), and it cannot "take back" code licensed under CDDL - it can relicense their own copy, not the one in OpenZFS, because there's no "version 1 or newer" clause that allows backdoor change to license like typical GPL case.

To summarize: - Oracle isn't the only copyright owner - Oracle can't take back CDDL license - Oracle can't introduce new version of CDDL and magically change the rules

[cyphar]

> because there's no "version 1 or newer" clause that allows backdoor change to license like typical GPL case

There is actually, and in CDDL (unlike in GPL) version updates are an opt-out feature rather than being opt-in. This was inherited from the MPL (which the CDDL is based on). See section 4 of the CDDL:

> 4.1. Oracle is the initial license steward and may publish revised and/or new versions of this License from time to time. Each version will be given a distinguishing version number. Except as provided in Section 4.3, no one other than the license steward has the right to modify this License.

> 4.2. You may always continue to use, distribute or otherwise make the Covered Software available under the terms of the version of the License under which You originally received the Covered Software. If the Initial Developer includes a notice in the Original Software prohibiting it from being distributed or otherwise made available under any subsequent version of the License, You must distribute and make the Covered Software available under the terms of the version of the License under which You originally received the Covered Software. Otherwise, You may also choose to use, distribute or otherwise make the Covered Software available under the terms of any subsequent version of the License published by the license steward.

In fact this is the primary argument that people give when arguing that Oracle could very easily make OpenZFS GPL-compatible -- they just need to release a CDDL v2 which says "code under this license is dual-licensed under the GPLv2 and CDDLv1.1". This situation has already happened -- CDDLv1.1 used this mechanism to change the "license steward" from "Sun Microsystems" to "Oracle".

[p_l]

Updates in GPL, thanks to standard boilerplate provided by GPL and used for years, are opt-out.

With CDDL, Oracle declares they have the sole right to provide newer versions of the license. However at no time can they treat it as an "upgrade path" for third party code, and OpenZFS code is explicitly labeled with CDDL 1.0

All of that has no impact on OpenZFS code which remains unencumbered, including by patents (the patent license is, afaik, the part that makes it incompatible with GPL the most).