What is Plan 9?

9 hours ago (fqa.9front.org)

Plan 9 is still alive and kicking -- The next Plan 9 conference will be in Victoria, BC in Canada later this year.

https://iwp9.org/

9front averages several commits a day:

https://git.9front.org/plan9front/9front/HEAD/log.html

  • I’ve been on/off playing with 9front on an old laptop. I’ve been having a lot of fun with it, it’s fun to write code for, but i have had a hard time using it as anything but a toy.

    I would love to use it as my main desktop, but ultimately (and kind of unsurprisingly), the blocker is the lack of a modern browser and a lack of video acceleration.

    I’m sure I could hobble something together with virtualization for the former but I don’t see a fix for video acceleration coming.

    Maybe I could install it on a server or something.

    • I did the same with an old Thinkpad but somehow found it relies too heavily on the mouse. I might still go back to it because I love how far they've taken the "everything is a file" idea and would like to experiment more with that.

Why did BSD make Unix sockets something outside of the file system?

I can do this in bash but I always thought it would be more elegant to do a similar thing in C. I thought Plan 9 handled it more like this?

cat < /dev/tcp/localhost/22

SSH-2.0-OpenSSH_10.0

  • They did not have the original unix vision. and it is a lot easier to to design an interface as a programming interface than shoehorn it into a filesystem interface.

    I think having a filesystem interface is pretty great, and plan9 showed it could be done. but having to describe all your io in the [database_key, open(), close(), read(), write(), seek()] interface. can be tricky and limiting for the developer. It is pretty great for the end user however. Having a single api for all io is a super power for adaptive access patterns.

    I think the thing that bothers me the most about the bsd socket interface is how close it is to a fs interface. connect()/bind() instead of open(), recv()/send() instead ot read()/write() but it still uses file discripters so that stuff tends to work the same. We almost had it.

    As much as I like BSD and as great an achievement that the socket interface was, I still think this was their big failure.

    • I just think this sounds very elegant

      https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs#/net

      > Plan 9 does not have specialised system calls or ioctls for accessing the networking stack or networking hardware. Instead, the /net file system is used. Network connections are controlled by reading and writing control messages to control files. Sub-directories such as /net/tcp and /net/udp are used as an interface to their respective protocols.

      > Combining the design concepts

      > Though interesting on their own, the design concepts of Plan 9 were supposed to be most useful when combined. For example, to implement a network address translation (NAT) server, a union directory can be created, overlaying the router's /net directory tree with its own /net. Similarly, a virtual private network (VPN) can be implemented by overlaying in a union directory a /net hierarchy from a remote gateway, using secured 9P over the public Internet. A union directory with the /net hierarchy and filters can be used to sandbox an untrusted application or to implement a firewall.[43] In the same manner, a distributed computing network can be composed with a union directory of /proc hierarchies from remote hosts, which allows interacting with them as if they are local.

      > When used together, these features allow for assembling a complex distributed computing environment by reusing the existing hierarchical name system

      I remember first setting up NAT or IP masquerading around 1998. It seemed like an ugly hack and some custom protocols did not work.

      I use a bunch of VPNs now and it still seems like a hack.

      The Plan 9 way just seems very clean although you now have to secure the server more strongly because you are exporting filesystems from it and others are mounting it.

    • > can be tricky and limiting for the developer. It is pretty great for the end user however.

      This seems to be a great general principle of api design! The best apis are those that are hated by the developer and loved by the end users.

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The transition step between UNIX and Inferno, and between C and Limbo as main userspace language, by its authors.

Which tends to be forgotten when praising Plan 9.

  • Is it correct to say Golang is bringing Limbo to the masses?

    • Partially, Go still doesn't support a few Limbo features.

      However the influence is quite clear, plus the Oberon-2 style methods and SYSTEM package.

    • That might be Rust, actually. They have more in common with thoughts about type systems, built-in constructs, deterministic memory usage, etc.

      Limbo looks more like Go on the concurrency front, but that was inherited from Alef/Plan 9. That wasn't what Limbo brought to the table.

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IMO, the biggest curse of the Internet age is how Distributed OS's did not become mainstream. Maybe we should repackage these as Unikernels and run our apps using their distribution services directly on a hypervisor.

  • k8s is really just a distributed OS implemented on top of Linux containers, only with extra facilities for automated tuning, scaling and overall management that are lacking on bare plan9.

    • 9front it's far ahead of docker and crappy namespaces running on a libre reimplementation of a dead end Unix version. They did things right from the start. bind it's far superior to anything else.

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I would love to see more Rust on Plan9 implementations, IMHO, could be a good modern combination.

  • I don't know. I use a lot of Swift and C++ and while both are OK languages there is an absurd amount of complexity in these languages that doesn't seem to serve any real purpose. Just a lot of foot traps, really. Coming back to Plan9 from that world is a breeze, the simplicity is like a therapy for me. So enjoyable.

    If "modern" means complex, I don't think it fits Plan9.

    • As a Swift noob, I would appreciate hearing what these foot traps are. This is in the context of Swift as a systems programming language?

    • I don't know about Swift, but in C++, the complexity serves at least three purposes:

      1. Backwards compatibility, in particular syntax-wise. New language-level functionality is introduced without changing existing syntax, but by exploiting what had been mal-formed instructions.

      2. Catering to the principle of "you don't pay for what you don't use" - and that means that the built-ins are rather spartan, and for convenience you have to build up complex structures of code yourself.

      3. A multi-paradigmatic approach and multiple, sometimes conflicting, usage scenarios for features (which detractors might call "can't make up your mind" or "design by committee").

      The crazy thing is that over the years, the added complexity makes the code for many tasks simpler than it used to be. It may involve a lot of complexity in libraries and under-the-hood, but paradoxically, and for the lay users, C++ can be said to have gotten simpler. Until you have to go down the rabbit hole of course.

  • AFAIK there is no Rust compiler for Plan 9 or 9front. The project is using a dialect of C and its own C compiler(s). I doubt adding Rust to the mix will help. For a research OS, C is a nice clean language and the Plan 9 dialect has a some niceties not found in standard C.

    If you really want Rust, check this https://github.com/r9os/r9 it is Plan 9 reimplemented in Rust (no idea about the project quality):

    R9 is a reimplementation of the plan9 kernel in Rust. It is not only inspired by but in many ways derived from the original Plan 9 source code.

  • I’m fairly sure that Rust compiler is bigger than the entire 9front (and 9front has Doom in it).

    • Since Rust depends on LLVM, which is massive, that is almost certainly true. It seems likely even if you don't include LLVM though.

  • You would like Golang more than Rust. At leat the authors (and ex-authors) for sure they are aware of Go, they invented it too.

>9front.org frequently questioned answers

Knowing that project am I going to be rickrolled?

Is there Plan9 port for RISC-V (RV32I) ?

  • Probably not. And there aren't many 32-bit RISC-V cores with an MMU. I guess you can use a simulator if you found one.

    • I use one written in SpinalHDL. :-)

      Next question is how much RAM it needs to boot and can it be used without rio ?

I’m not sure it still makes sense to do OS research so close to the metal. Most computing is done up on the application level, and our abstractions there suck, and I haven’t seen any evidence that “everything is a file” helps much in a world of web APIs and SQL databases

  • Some of us are still interested in the world underneath all that web stuff!

    Multiple experimental operating systems at multiple abstraction levels sounds like a good idea, though. What sort of system software would you like to build?

    • Operating systems are where device drivers live. It sounds awfully impractical to develop alternatives at this stage. I think OP is right.

      I think OSes should just freeze all their features right now. Does anyone remember all the weird churn in the world of Linux, where (i) KDE changed from version 3 to 4, which broke everyone's KDE completely unnecessarily (ii) GNOME changed from version 2 to 3, which did the same (iii) Ubuntu Linux decided to change their desktop environment away from GNOME for no reason - but then unchanged it a few years later? When all was said and done, nothing substantive really got done.

      So stop changing things at the OS level. Only make conservative changes which don't break the APIs and UIs. Time to feature-freeze, and work on the layers above. If the upper layers take over the work of the lower layers, then over time the lower layers can get silently replaced.

  • Idk I still find low level OS stuff super interesting because it hasn't had a rework in so long. With everything we've learnt since the age of modern computing, drives larger than a few MBs, super fast memory and fast cryptography to name a few.

    It's interesting to imagine a new OS that incorporates these changes from it's infancy.

    I appreciate all of the effort put in by Linux, BSD, Android, QNX and closed source OSs' have put in to building upon existing ideas and innovating gradually on them. But man I really want to see something better than everything is a file. I really enjoyed the stuff BeOS was pitching.

    • Well, on the file system side BeOS was pitching "virtual folders" that are really no different than what plan9 provides.

  • I didn’t really see the appeal until I learned how to use FUSE.

    There’s something elegant about filesystems. Even more than pipes, filesystems can be used to glue programs together. Want to control your webcam with Vim? Expose a writable file. Want to share a device across the network? Expose it as a file system, mount that filesystem on your computer.

  • The "everything is a file" approach is nice in many cases, I'm worried though if it works everywhere. Maybe if done right. Subversion (SVN) shows branches as separate file trees.. and ClearCase too (though I'm on thin ice with ClearCase, having used it very little). And I just can't stand the file-oriented way SVN works, I could never get used to it. But there are a lot of other cases where "it's a file" does work, I've experimented with creating Fuse filesystem interfaces to some stuff now and then.

  • > I haven’t seen any evidence that “everything is a file” helps much in a world of web APIs and SQL databases

    Well for one thing, such an abstraction enables you to avoid web apis and sql databases!

    • You're going to have to explain to me how a parametrized request/response system like calling a Web API or making a SQL query can be mapped to reading files. I've seen some stuff that people do with FUSE and it looks like ridiculous circus hoop jumping to making the Brainfuck-is-Turing-complete version of a query system. We have syntax for a reason.

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