Title is misleading. Plan 9 was, and continue to be LPL. The Labs just made a special arrangement with these guys from Berkeley for them to distribute Plan 9 under dual-licensing terms. They in turn integrate Plan 9 bits into their GPL operating system (akaros).
Plan 9 as distributed by the labs continues to be LPL (not GPL and not dual licensed).
I'm confused. If Berkeley received a GPL license for Plan9, doesn't that mean they can redistribute it under the GPL?
From the GPL:
You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.
I'm assuming "it" in this case refers to the Plan 9 code.
The labs still only distribute Plan 9 under its own license. Now Plan 9 is available also underthe GPL, but the labs doesn't distribute that version. it's only relevant if they continue to work on it and don't continue to share their changes under the GPL.
At worst, there will be a fork under GPL and they will slowly diverge.
My understanding is that the Berkley guys develop akaros and have no interest in maintaining a Plan 9 fork (they just want to integrate some Plan 9 code). Of course, other parties are free to fork the GPL version (not that this will ever happen).
Now that there's a GPL version, it does mean other developers of Linux derivatives, or of Linux itself, could mine bits and pieces of the code, though, just like Akaros is doing. I agree a long-running GPL-licensed Plan9 fork isn't that likely, but now that there's even a one-time dump of the code under the GPL, it removes the legal barrier to kernel devs cherrypicking pieces of the Plan9 code and integrating them into patches. For example, the developers of Linux's v9fs implementation can now borrow code from Plan9's 9p implementation, if they choose.
Sure they can. So what? The "real" Plan 9 continues to be developed and distributed by the labs as LPL.
I don't know if the Berkley guys just got a bag of GPL code or if this is a continuous agreement, and they'll get subsequent, more recent code in the future. In the meantime, code from Bell Labs is LPL.
> The "real" Plan 9 continues to be developed and distributed by the labs
Are there still employees on the project? I had been under the impression that the entire core dev team left in 2003, mostly for Google, and that Alcatel-Lucent no longer staffs the project. Looking through the last-modified dates in the source tree, there are a handful of edits in the last few years, but not very many, and the only specific people I can find who've worked on plan9 in the past 5 years are all external to Bell Labs (e.g. the 9front people).
There's definitely more activity outside the labs than inside, however there are still a few Bell Labs people who work on it. For example, the new MIPS kernel was entirely labs work.
Networking equipment, various set-top boxes (the WDTV Live is a good example, running on a tri-core Sigma MIPS CPU; two cores are user accessible, the third is locked down to run DRM crap), some Android devices. Bunch of other embedded uses.
As I noted elsewhere, at least as of a year or two ago MIPS was likely still outselling x86 in terms of volume (but x86 is still supreme in terms of revenue because all the other architectures have far lower average unit costs).
What is the point of anything? What is the point of life. There is no point, the point is that people have fun working on things they tickle their intellect. People are motivated by things that are hard, beautiful. People are motivated by things that haven't been done before. People are not motivated by the usefulness of a thing.
Plan 9 is a research operating system, it's a platform to do fundamental operating system research. It is not a product, and its development is not shaped by commercial interest.
That being said, Coraid hardware runs Plan 9, it's embedded, you don't see it. They also make all their development on Plan 9.
"Plan 9 shows up in lots of different types of applications, making use of different benefits. It is used in embedded systems, where the low overhead is important. It is used in commercial products where the reliability and performance are important. It's used in massive supercomputers where the novel interconnections and low "system noise" are needed. What you get out of it largely depends on what you're looking for from it."
Most routers are MIPS. There are probably more MIPS devices coming out each year than ARM devices, it's just that they are in very small devices and now in fancy phones.
Last I saw, the estimated number of units shipped for ARM was around 3 billion, with MIPS and PPC at around 500 million, and x86 somewhere in the 300m-400m range.
You might be right, I might be wrong. We'll never know. I tried to find good numbers, but estimates seem to be made up; e.g. between 1 and 10 billion ARM CPUs each year. I couldn't find good data.
Either way, even if MIPS doesn't dominate anymore, it's still a huge market (probably more chips than x86), and will continue to be in the future (even though it might be shrinking).
Plan 9 as distributed by the labs continues to be LPL (not GPL and not dual licensed).