As I understand it, including ZFS requires all linked code to be bound by the CDDL, which the GPL cannot do.

https://sfconservancy.org/blog/2016/feb/25/zfs-and-linux/

"[§]3.1 … Any Covered Software that You distribute or otherwise make available in Executable form must also be made available in Source Code form and that Source Code form must be distributed only under the terms of this License. …

"[§] 3.4 … You may not offer or impose any terms on any Covered Software in Source Code form that alters or restricts the applicable version of this License."

It's the opposite way - GPL automatically covers the final product, and does not allow for licenses that have stronger terms than itself.

CDDL is per-file license, does not automatically extend itself to the whole product. But it also has wording about patents et al, which puts it beyond direct inclusion in kernel just like MPL.

Out of tree with one degree of separation (Solaris Porting Layer) is based on the precedent of AFS implementation for linux, where the argument was that the code is not derivative of Linux kernel code, as in no way was VFS unique to linux or any other crucial part involved.

> CDDL is per-file license, does not automatically extend itself to the whole product. But it also has wording about patents et al, which puts it beyond direct inclusion in kernel just like MPL.

Well, MPLv1 was incompatible with the GPL. MPLv2 has an explicit clause to make it compatible (namely to allow relicensing within limits). I would imagine the lack of "relicensing within limits" would be the key problem with CDDL and GPL -- since CDDL was based on MPLv1.

> Out of tree with one degree of separation (Solaris Porting Layer) is based on the precedent of AFS implementation for linux, where the argument was that the code is not derivative of Linux kernel code, as in no way was VFS unique to linux or any other crucial part involved.

Right, especially since the ZFS source code was developed completely separately to Linux and the SPL is licensed GPL+CDDL. This is the same thing that NVIDIA does with their drivers (they even build their driver binaries on FreeBSD to show that it "couldn't possibly" be a derived work of Linux and have a GPL shim).

But Ubuntu figured it was ok to ship with zfs.

https://blog.ubuntu.com/2016/02/18/zfs-licensing-and-linux

Though FSF doesn't seem to support it.

https://www.fsf.org/licensing/zfs-and-linux

And a few HN posts regarding the Ubuntu's announcement.

https://news.ycombinator.com/item?id=11125063

https://news.ycombinator.com/item?id=11240402

> But Ubuntu figured it was ok to ship with zfs.

Having spoken to some Canonical folks involved in this discussion, basically it boils down to the fact that the SPL (Solaris Porting Layer, which converts Linux VFS APIs to Solaris ones for ZFS) is GPL licensed and that ZFS was developed entirely separately from Linux (and Torvalds has said he agrees with the latter point). It also helps that ZFS is free software.

Honestly I think their strategy is that it's very unlikely they'll get sued (not to mention the past 5-8 years of OpenZFS development was done without an Oracle CLA). IMHO the FSF is primarily against it because they think it might water down the GPL's effects.

>But Ubuntu figured it was ok to ship with zfs.

Yes, but it's shipped as a separate kernel module (as in separate file) rather than built into the Linux kernel. As for the legality of this, it can really only be determined in court, which hopefully won't happen since I can't think of anyone who would want to prevent Linux from using ZFS now that Sun is gone.

It would be great if it could eventually be part of Linux mainline which would then allow it to easily be used on boot volumes as well. That would require dual/relicensing though, since Linus Torvalds have said that CDDL code will not be merged with mainline (most likey a result of consultation with Linux Foundation lawyers).

> I can't think of anyone who would want to prevent Linux from using ZFS now that Sun is gone.

Oracle? I doubt they would, but I mean, it's Oracle.

I get you point but Oracle don't really seem all that interested in maximizing Solaris.

The problem we have is Oracle also don't seem at all interested in maximizing ZFS either. So they'd quite happily see both die.

Only until they figure suing others would be worth a grab for them.

That doesn't contradict my statement.

One can be aggressively litigating using ones IP while also letting the technology behind that IP die.

> prevent Linux from using ZFS now that Sun is gone.

Considering btrfs isn't really going anywhere why would they not rather take the effort to relicense zfs than put any effort on btrfs if they have no bad intention with zfs?

Fixing zfs' situation surely can buy some mindshare for Oracle.

Definitely feels like it. OSX had its "we're onboard with ZFS" moment which vanished. I am believing this was a licence fubar.

I doubt it would have gotten announced w/o the approval of their giant army of lawyers.

Apple AFAIK started work with Sun in charge - it was Oracle getting its hands on Solaris tech that had Apple pull out.

Because Lawyers? or because nobody like Larry?

Why not both?

Or they just figured they wanted a file system that also works on mobile devices (apfs even works on watchOS) with limited memory.

I could wear the ZFS thing was from so long ago that APFS wouldn't even have been a glimmer in an Apple engineer's eye. 10.5 or 10.6?

Yeah, there was a period between ZFS not happening and APFS really starting, as far as one can tell.