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1. So how does FreeBSD ship it? I thought their whole OS (kernel+main userspace) is under a BSD lisence.

2. Why can't Linux vendors ship source code to be compiled on clients computers, so no distribution (forgot the legal term) takes place?

3. If the patent license only covers the code they released (and they reserve the right to sue over reimplementations), what will FreeBSD (or illumios) do if they'res a bug in the code? Once you change the code, you very sued

1. CDDL is fully BSD compatible. The license is file based, so it's non-infecting, and binaries can be re-licensed. Win/win.

2. Most already do. Some even believe that 1 makes CDDL compatible with GPL as well and so ship binaries.

3. Patent protection in CDDL is extremely strong. Rumor has it that Oracle wanted to kill illumos via litigation, but never went ahead with it because they knew they'd never win because of the CDDL.

3. So why can't Linux black-box re-implement it?

In my opinion, reimplementing ZFS from scratch would cost at least $100 million and take 5 to 10 years of development by many talented people. Given that we already have the source code under the CDDL and it is good enough, no one is willing to spend that kind of money. Why would they? There is no business case.

If anything, Oracle's software patents are a case against it because they could sue a clean room implementation like they did with Android's Java implementation. They would have a stronger case too due to the hundreds of patents covering ZFS. That is the elephant in the room with btrfs that no one discusses. :/

Anyway, I see no need to reimplement ZFS from scratch after consultation with attorneys of the SFLC and others.

Linux has a black-box reimplementation of DTrace (with different design sensibilities, but essentially all the same functionality) under the name of eBPF, and bcc for the userspace bits. Linux is trying to do that for ZFS under the name of btrfs, but it's not as good.

Oracle also ported Dtrace to Oracle Linux, and was available if you purchased support from Oracle.

> 2. Why can't Linux vendors ship source code to be compiled on clients computers, so no distribution (forgot the legal term) takes place?

For ZFS, they do. Debian's legal advisors say that shipping it as a DKMS module (i.e., as you describe) is fine, so they do that.



Ubuntu's legal advisors say that shipping the compiled module is fine, so they ship that.


DTrace is rather more closely coupled to the kernel than a filesystem, and there are good Linux-native alternatives now.


FreeBSD ships a large chunk of software under licenses other than BSD, and used to ship even more until the last couple of versions.

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