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Plan9-9k: 64-bit Plan 9

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Actually I would rather see someone pick up Inferno and replace Limbo with Go.

Personally I see Plan9 just as a plain transition step between UNIX and Inferno, where the goodies in terms of architecture actually are.

There is an inferno with lua project, on this theme; see https://news.ycombinator.com/item?id=9704517

I think you are the first person I've seen speak highly of Inferno. I've played with Plan 9 from time to time, so if you have a moment, can you tell me what you like about it?

Sure, are you aware of Inferno's web site?

http://doc.cat-v.org/inferno/4th_edition/

It contains quite some useful information, including the book "Inferno Programming with Limbo" http://doc.cat-v.org/inferno/books/inferno_programming_with_...

Being a security oriented developer, I like that they decided to use a managed language for the whole userspace (Limbo) leaving C for the kernel and compatibility with UNIX software.

Basically, the distributed computing ideas and Oberon influences from Plan 9, merged with type safety.

In a certain way, what Android came to be, almost 20 years before it existed.

Do you see a difference between a "managed language" vs. isolation (by means of containers and/or VMs).

Personally I don't; meaning it should be as good to run software in a jailed environment and not force the choice of language on developers.

I am curious to see what others think of this, though.

I see a difference when the language doesn't provide mechanisms to enforce program integrity.

With a type safe language, being used alongside isolation mechanisms, I get two layers of protection, at language level and at the sandbox level.

Like Android or ChromeOS do with their managed environments + Linux SE and on Samsung's case Knox.

If the language is unsafe, everything outside the jail might be safe, but the program integrity or the data inside of the container are exposed to the attackers.

If I get RCE in your mail client I read your email. Not letting me persist doesn't help much more.

How does the choice of language prevent that? Sure different languages might make that harder, but I don't know of many that don't allow arbitrary code, written by a random developer, to execute poorly defined HTML parser to possibly exec some hostile code.

There are facilities and standards in most languages to help prevent this, but can you point out why this is not possible in Limbo? I'm not personally familiar with it.

Sure preventing logical errors is hard, but it is already an improvement that typical C errors aren't possible.

Limbo does not support this, but both Java and .NET allow for security control at class and method level, however they tend to be misunderstood by most developers, which don't regularly use such features.

Inferno is cool.

I agree 100%. I do wonder if the Dis VM is a close enough match for Go as a target. Or perhaps we could start with a simple Go to Limbo translation transpiler. Want to see if it's possible?

> I do wonder if the Dis VM is a close enough match for Go as a target

obviously you would call this DisGo and the resulting system would be DisGo Inferno

Better just call it Dante or Dante's.

It's clever, but "Dante's Inferno" is one of the few names more difficult to google than "go"

You would google for golang

But this would need a Go with generics and polymorphism then. PolyGo or such. For simple server stuff Go is enough but for a dynamic VM with dynamic objects not.

Can you elaborate on your thoughts here? If you just wanted to target the Dis VM using Go as the starting point, I believe you could call most everything in the standard libraries.

That would be nice, but I'd probably prefer to have a UI that I could use without a three-button mouse...

Then you can either settle on Windows or OS X, I guess.

My X Windows is a bit rusty, but I remember most managers use all three buttons.

Most modern managers don't, or at least do not assume you have a middle mouse button.

The real issue for me is laptop trackpads. It's impossible to use Plan 9 (or derived works) with one in a natural fashion.

I've always had a soft spot for Plan9 (on account of its architectural purity) but I've never managed to make it a ”daily driver” despite sincerest efforts (this coming from somebody who fondly remembers using BeOS pretty exclusively for at least a couple of years in the latter half of the nineties).

Maybe this will reignite interest in the platform? Maybe somebody will go ahead to port it to 64 bit ARM so it can be tried on the latest Raspberry Pi? (Yes I know the 32 bit version exists and works, but...)

There's Plan 9 Front.

http://9front.org

I've used Plan 9 a few times in the last handful of years.

Someone got a reasonably good Linux emulator working enough to run Firefox. What more could you need? (ok it was fairly limited in some ways, but shoot once you have a web browser, most of the rest is cake... especially if it's Chrome, because then you can install Mosh inside it!)

Not sure if that's practical on Plan 9 right now.

Call me odd, but I like native software — web-apps et al are not my style. Similarly, bastardising everything so Linux binaries run on it kind of defeats the point (at least in my mind). But yeah, I'm odd.

> bastardising everything so Linux binaries run on it kind of defeats the point

Is there all that much of a difference between the kind of "secondary syscall ABI" approaches that allow OSes like Windows and Illumos to virtualize Linux binaries, and autoconf-based porting of those projects so they compile for the target OS, if they only use POSIX facilities that both OSes offer the same way anyway?

I mean, I agree with you when it comes to e.g. programs that use heavy amounts of OS-specific concurrency or IPC primitives. Postgres in WSL on Windows does not have the same concurrency semantics as MSSQL on Windows does, because Postgres is using POSIX concurrency primitives and MSSQL is using NT concurrency primitives.

But if there's a subset of your kernel's syscall ABI, that already has those same semantics, and really can just be 1:1 mapped with maybe a few extra instructions to handle different argument passing conventions—then does porting such a program to the OS really achieve anything?

Ok, well I lived in google chrome mosh for about 4 months. It was fine :-) Full screen too.

A common thing to do here is to virtualize 9front, connect back to a VNC window hosting Chrome. It sounds really janky but it's genuinely difficult to tell that you're not inside Chrome -- people have even asked "How in did you port Chrome to Plan 9.

"Someone got a reasonably good Linux emulator working enough to run Firefox. What more could you need?"

It would be nice if Plan 9 had vim or emacs.

It does, Vim is available through pkg on 9Front and works really well. The only thing I would say is that `:Ex` works a little funky (although generally quite well).

Furthermore there exists "A Posix Emulator" (ape) that is serviceable.

ACME FTW. :)

A mouse-oriented editor? That's about the opposite of what I'd want.

Mouse oriented editors combined with keyboard shortcuts, is like playing FPS with a PC against console gamers.

Or maybe it just shows my bias for IDEs. :)

I think it is worth noting that acme, the editor, borrows heavily from N. Wirth's Oberon, the OS.

It wasn't a year back, at least for relatively recent versions. Nothing substantial has changed, so I think it still isn't

I didn't know Mosh until now. Thank you so much for mentioning it! :-)

I've read a lot of places that say "Plan 9 is basically a better Unix", but I'm not entirely sure why. Can someone explain what made Plan-9 special? I'm not asking in a passive aggressive sense, I genuinely want to know.

Plan 9 shows that you can reduce the complexity of Unix by changing the idea behind mount slightly (mounts are inherited by processes rather than global) and creating a simple network filesystem protocol that applications can use to expose their state through.

In Unix you often get stuck having to create these walled-off systems. Your editor's inner state, for instance, is not visible to other applications, so you need to come up with your own whole programming scheme. Same with your window manager. And all your networking happens through a separate set of APIs that are similar to the file descriptor APIs but different enough that nothing works transparently.

Once you have per-process mounts and a simple network filesystem, all your applications and devices can start exposing their state over that protocol. All your software and hardware are automatically networkable if you follow the design. And you can use Unix utilities to do things that previously would require whole subsystems to be built. You don't need to build your own programming language for Acme, because Acme's state is visible as a filesystem. Same with the window manager. And you don't need to build a custom networking scheme for sharing Acme with your friend on another machine, because you can export Acme's filesystem to that machine (or have your friend export their keyboard onto your machine as a child of the Acme process).

"Everything really is a file" is a good way to sum it up. But that's only possible and relatively safe because of 9P and per-process namespaces.

> Your editor's inner state, for instance, is not visible to other applications, so you need to come up with your own whole programming scheme.

> Same with your window manager.

> You don't need to build your own programming language for Acme, because Acme's state is visible as a filesystem.

I don't see how it's good programming practice to expose your internal state to direct read/write access from other programs. It seems to violate basic encapsulation principles.

Your quotes are making me think of some really important takeaways from the Longhorn disaster with WinFS, detailed in a recent submission[1]:

> More profoundly, Bill’s vision of an ecosystem of applications that all store and share their data in this relational store is in direct conflict with how applications build their data models. While some desktop applications (and almost all internal IT-written ones) use relational stores for their internal data model, they do not want to expose those data models for unmonitored read and write by other applications. I detailed some of the fundamental reasons in the post referenced above, Leaky by Design.[2]

Solutions like this... "what if application state were like a relational data store, or hierarchical FS, that other programs can access", sounds great as a fun programming exercise, but it isn't often how people actually want to design applications.

[1] https://hackernoon.com/what-really-happened-with-vista-4ca7f... [2] https://hackernoon.com/leaky-by-design-7b423142ece0

By "inner state", the parent didn't mean literally the RAM or disk storage used internally by the application, just the logical state that belongs to it. A Plan 9 filesystem is just an interprocess communication API that happens to be structured in terms of virtual 'files' and file operations, kind of like what REST does with HTTP. The application handles all requests itself so it can always limit access or enforce invariants, which was absent in the Microsoft examples you linked.

Exactly.

that sounds really simple and powerful. i am keen to start following this project. Is there a patreon or a donation portal to help fund development?

This isn't really a ’project’ in the sense you seem to intend: it was a 1990s AT&T research project that was abandoned and released under an open source licence in the mid-2000s.

Bum deal. There seems to be some interest at least here on HN, perhaps someone or a group of someones could pick it up and bring it to bear for 2017+?

There is Harvey OS, it's a direct descendant of Plan9 and they accept donations.

https://github.com/Harvey-OS/harvey

The development seems active, the last commit was made 7 hours ago.

Last time I checked the project was still in its early stages. Docs and stability have improved a lot since then.

Sidenote: I think 9P protocol and plan9 userland like ACME editor is available on linux.

Donated. Dropped them a line about a bootable iso

I don't have a ton of cash but I believe in the hacker culture and as an aspiring developer I figure I'd put my money where my mouth is.

Congratulations, HarveyOS is really an intriguing project to support.

It would be nice, if they'd provide an ISO. The thing I noticed about Plan9 clones and Inferno is that, they almost always run entirely in the userland. I think that's the reason HarveyOS does not provide an iso. I am not sure they are building a standalone operating system.

If you're interested you could also try inferno, however getting it up and running is also a hassle.

Lastly, in the case you're not aware, Plan9 and inferno also have a very interesting history. Inferno and Java were once direct competitors. Limbo a programming languages invented for Plan9 is also mentioned in the Dan Brown's best seller Digital Fortress.

IMHO Plan9 spirit still lives in Golang, like the Lisp Machines' spirit lives in Emacs. Maybe with cloud based OS's we could see the ideas behind Plan9 in everyday world. But other than that Plan9 remains an OS for hobbyists and idealist computer folk :).

> It would be nice, if they'd provide an ISO. The thing I noticed about Plan9 clones and Inferno is that, they almost always run entirely in the userland. I think that's the reason HarveyOS does not provide an iso. I am not sure they are building a standalone operating system.

This is a property exclusive to inferno.

Awesome. Thanks.

Wait, are people actually taking plan9 seriously now?

All the Docker (namespaces and cgroups) in Linux seems like a bad copy of Plan9. I'd say yes, but not seriously enough.

That's a really good way of putting it. I could see Plan9 being relevant today. A "unified system" is pretty much what all the cloud stuff is attempting to approximate (and more poorly, of course).

Probably not. But tinkerers love to mess with it.

Everything is a file system. You can mount almost all things. All things have private namespaces by default.

Right down to the TCP/IP stack... you can run a program called "sshnet" and connect to a remote unix box, the /net in that process' namespace now has a tunnel to the remote box, and all children of that process that opt-in to share the namespace now have a VPN-like to the network you just ssh'd to.

Because the network stack is a file system you can do basic open, read, write, close stuff to dial up remote services and work with them. As such there's IRC clients written in the shell, without evil extensions like /dev/tcp in bash.

It's fun, but it doesn't outrun any other OS I've seen. Maybe that's changed.

Honest question: If we extend dbus to be similarly pervasive in Linux (via BUS1 or whatever ends up being merged), won't it have pretty much the same benefits? Once it's in-kernel I'm 100% sure we'll end up with a virtual file system for accessing it. It will definitely never be quite as elegant and integrated in the system as Plan9, but maybe we could reap similar benefits?

Well the nice thing, maybe, about Plan 9's virtualization of resources is that they all follow some 9P variant (simple protocol).

9p is v9fs in linux. There's FUSE 9p stuff for other platforms. There's a virtualized Erlang runtime that sits directly on Xen as the OS that uses 9p. 9p is part of QEMU's way of talking to the guest (or is it the host?) OS.

It's been on a lego mindstorm brick too.

To me, kernel dbus is a bit more like mach_ports. Those have their own advantages too. As did Solaris Doors.

> If we extend dbus to be similarly pervasive in Linux

That kind of pervasiveness involve replacing all i/o through the entire system with dbus. File systems, netlink, sun rpc, mmap, signals and kill, tcp, and so on.

And then making dbus sanely deal with networking and authentication.

9p isn't just pervasive: it's the only way to talk to the system, which means that if you want to mess with namespacing things, all you need to think about is 9p.

Linux is no longer pure Unix. Linux has adopted parts of plan 9.

Somehow many Plan 9 fans seem to forget that the design continued as Inferno.

So with that in mind, I would rephrase that as "Inferno is basically a better Unix".

You can learn more about it, including the programming manual with lots of Limbo examples at:

http://doc.cat-v.org/inferno/4th_edition/

You can easily see some of Go's pedigree on Limbo's design.

Nowadays Inferno is still being sold by Vita Nuova, the company that acquired the rights after Bell Labs folded the project.

http://www.vitanuova.com/inferno/

Go and Limbo have newsqueak as an ancestor.

https://en.wikipedia.org/wiki/Newsqueak

Alef was pretty neat too and was also on Plan 9

https://en.wikipedia.org/wiki/Alef_(programming_language)

In Plan 9, everything literally is a file. Processes communicate using the 9p protocol which is also the basis of the file system; each process also has its own, local view of the file tree which children can inherit (or not). To do IPC with a server process, simply mount it and begin reading and writing to files in the mounted directory. Oh, and 9p is network-transparent, so you can see remote files and processes as if they were local.

It really is a neat idea, and shows what can be done when you take an idea to its logical extreme. But the interface is not human friendly. Real-world workloads are complicated and require kernels that handle the weird edge cases so you can't reduce a production kernel to a simple idea. And 9p performance lags behind other networked file systems. So it's really more of a prototype and a laboratory for generating ideas to be used in other systems, rather than a replacement for production Unix.

In a nutshell, and somewhat simplified: it cleans up the /dev/ interface and turns everything into streams of characters and mounts. So rather than a bunch of messy ioctls and other out-of-band mechanisms it just works with streams. This is nice because it allows you to use remote resources as if they're local.

Distributed name spaces, distributed computing, compute servers, distributed file servers and so on.

Remember the SUN slogan 'the network is the computer'? Plan 9 makes that a reality.

In Plan9 UNIX's ”everything is a file” philosophy is reaffirmed in a heightened and enhanced form, and all resources (CPUs, even) on a distributed network can be mounted with a simple protocol and accessed remotely. These namespaces make it possible to provide each and every program with its own namespace (to the point of being able to run a copy of the window manager within itself). For example you have /net directories with all the TCP ports in /net/tcp and those can be concatenated to forward ports or even create routers. It's amazing.

I've played with Pla9 a bit and I find it overall interesting. Here are the things from the top of my head that are improvements over Unix:

- Truly everything is a file. No exceptions; no special cases.

- Symlinks do not feel like a hack causing trouble. If you need a reference to a directory in another path, you mount it. If your software writes its binaries into its custom directory and you want the binaries within the $PATH, you mount that custom directory into /bin (or so, from what I remember).

- Namespace isolation for processes.

- Distributed file system

> - Namespace isolation for processes.

This is seriously underappreciated IMO. You can entirely replace access control with private namespaces without any real loss in generality. In fact, they're more flexible and secure.

And actually that's exactly what the FreeBSD Jails paper says too. Their aim was to make uid 0 more granular by segmenting the system so that you have different access control in those jails.

You see some of these ideas in Linux, but as with all Linux kernel technologies they all feel like they've not been written with a design in mind from the start (just look at epoll, namespaces, /proc, and so on).

All UNIX flavours are pretty late to the party though, even plan 9. This sort of isolation was a feature of most capability operating systems since the 60s.

> Truly everything is a file. No exceptions; no special cases.

As graphics fan, I wonder how this would work out with modern GPU driver layers.

John Carmack used to participate in the Plan 9 mailing lists

https://marc.info/?a=111558719100068&r=1&w=4

Though Rob Pike might have not been very cooperative or enthusiastic

https://marc.info/?l=9fans&m=111558699517143&w=4

He goes on about some interesting architectural advantages already in Plan 9 from a graphics programming standpoint and capitalizing on them someday.

It'd be interesting to hear about how far along he got.

https://marc.info/?l=9fans&m=111558698816997&w=4

Here he talks about trying to hack Plan 9 to run Quake https://marc.info/?l=9fans&m=111558698416915&w=4

Interesting read, including some QNX and Amiga related stuff, thanks.

I think ESR summarized it very well for the layman almost 20 years ago in "the art of unix programming":

http://catb.org/~esr/writings/taoup/html/plan9.html

It's probably more accurate to say it was intended to be the successor of UNIX. Plan 9 was developed by the same group that developed UNIX (Bell Labs) with many of the same prominent people credited with C and UNIX; Rob Pike, Ken Thompson, Dennis Ritchie.

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

It's a truly distributed operating system and it's unix taken to it's logical conclusion. Everything is a file and everything is network transparent, thanks to 9P. The first wikipedia article is very worthwhile reading - this is a little except that gives you the idea:

> "Unix allows file systems to be built up from disparate resources using concepts such as links and file system mounts. These features masked the original directory; if one mounts a new filesystem on the directory named "net", one can no longer access its previous contents until the operation is reversed.

> Plan 9 introduced the idea of union directories, directories that combine resources across different media or across a network, binding transparently to other directories. For example, another computer's /bin (applications) directory can be bound to one's own, and then this directory will hold both local and remote applications and the user can access both transparently.

> Using the same system, under Plan 9 external devices and resources can be bound to /dev, allowing any device to be shared over the network without any additional code."

So, you can union mount other machines /dev/cpu/ folders into your machine's /dev/cpu folder and then have access to all the CPU's. Same for all other hardware, software and storage.

Just these two things - Union Mounts and 9P - when built into the whole system, create a very dynamic distributed computing environment. I really, really wish more of this would make it into Linux. We've kinda got some of it, but without joining up all the other bits, the real power isn't quite there.

http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs http://plan9.bell-labs.com/plan9/ http://en.wikipedia.org/wiki/9P2000 http://en.wikipedia.org/wiki/V9fs http://en.wikipedia.org/wiki/List_of_distributed_computing_p... http://en.wikipedia.org/wiki/Inferno_$operating_system$ http://doc.cat-v.org/plan_9/4th_edition/papers/plumb http://swtch.com/plan9port/

"Just these two things - Union Mounts and 9P - when built into the whole system, create a very dynamic distributed computing environment. I really, really wish more of this would make it into Linux."

Union mounts and 9P are already available in Linux.[1][2] What other things would you like to see?

[1] - https://lwn.net/Articles/325369/

[2] - https://www.mjmwired.net/kernel/Documentation/filesystems/9p...

Union mounts only went into the linux kernel 3 years ago (2014) - and have lots of limitations.

It's also not really a central concept. plan9 doesn't have a $PATH env var, for example - you just union mount all your binaries into `/bin`.

Again, yes there's an implementation on 9p for linux - but it's not baked in and it's not used by the system as a unifying abstraction - this makes it fairly useless:

> Unlike most other operating systems, Plan 9 does not provide special application programming interfaces (such as Berkeley sockets, X resources or ioctl system calls) to access devices.

> Instead, Plan 9 device drivers implement their control interface as a file system, so that the hardware can be accessed by the ordinary file input/output operations read and write.

> Consequently, sharing the device across the network can be accomplished by mounting the corresponding directory tree to the target machine.

It's really having this stuff baked in and then combining them that gives you the power & elegance: https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs#Combinin...

> What other things would you like to see?

C replaced by Go, as Inferno replaced it with Limbo for userpace applications.

Go? Why not Rust or a safe language like SML? Personally, I'd much prefer Scheme for user apps.

I agree with you, but given the similarities of Go and Limbo, with the increasing love of system administrators to it, it seems an easier sell.

As for your SML hint, I leave here "Unix system programming in OCaml" :)

https://ocaml.github.io/ocamlunix/

A little bit of history: Forsyth did the 64-bit compiler for the Plan 9 on Blue Gene project.

http://doc.cat-v.org/plan_9/blue_gene/

(I contributed to the project too: I did the photochop of glenda on the side of the BG racks! ;)

Forsyth is also "the Inferno guy" (well, one of them!). I've had a lot of fun playing around with that little OS over the years.

http://vitanuova.com/inferno/index.html

It can run without an MMU too. It's been ported to the Nintendo DS.

I'd love to be able to sit down and learn Plan9. The shell is awesome (rc), the commands are somewhat familiar, but the networking is totally foreign and security setup (factotum I think) I obtuse. I want a Plan9 kernel with no security for playing and architecting with...they took a great idea and ruined with security. That should be the outer layer of the system.

Richard Miller's port of plan9 runs on every RaspberryPi (pi0 to pi3 - where it uses all the cores). This may be the easiest way to experience plan9 and to build a small distributed system. You can experiment with device drivers or do other kernel hacking fairly quickly -- compiling p9 kernel from scratch takes about a minute on a 'Pi. This is good enough if you just want to play with plan9. You need not bother with an x86 system unless you want to use plan9 as your main system or for some serious work.

Linkage: http://raspi.tv/tag/richard-miller-plan-9

The dream of the plan9 filesystem may be alive in upspin (https://upspin.io/). Its a federated filesystem/protocol with a global namespace. The security story could arguably be described as a layer on top of any application built with it in mind.

I've just begun experimenting with it on my personal server and like it so far. Its still an early project though.

Does it support remote devices like 9p?

"Imagine you have something like a security camera, or you're a parent, you got a new newborn, you want a nursery camera.

You can put the camera into upspin by running a little directory storage server nearby -- or on the camera depending on how much control you have -- and then you've got access to the data whether it's a video stream or a series of static frames. Whatever it is. But it's encrypted, it's accessible only by the people in your family, which might be the name of an upspin group you created. It has you your wife and your other kids, or whatever. " - Rob Pike on Upspin at GopherCon 2017

https://youtu.be/giUatBmmb_Y?t=1h38m3s (talk starts at 1:19 https://youtu.be/giUatBmmb_Y?t=1h19m19s)

Yes, definitely you can shard your filesystem however you like or mount any remote system locally if thats what your asking.

There is currently a little research into what it looks like to expose something like a webcam as a file and how streaming interfaces look in the system, but, the client to stream the webcam file is a little hacky still.

No, what I mean is that with 9p you can remote far more than just filesystems. It's an IP based layer with the Plan9 kernel being a router for 9p messages meaning you can do things like 'mount' an audio card from another machine into your 'namespace' and use it like it's local; no magic required. It's all in the kernel.

Since, this system is a layer outside the kernel, just a bunch of normal applications I don't think this would work as smoothly. I think you'd need a custom storage server to serve the audio card from the other machine. It doesn't by default serve the entire host filesystem.

That said, I think the goal of upspin is that you easily can re-use its interfaces to do things like this. There are already some guides about writing custom shim storage servers like that (the main example being a webcam server), but I think this sort of experimentation is still in the early phases.

factotum is similar to kerberos iirc. Plan9 was deisgned as distributed computing environment(separating fs, cpu and auth). Although you can and many people do run all of them on same machine.

How would you remove it from the kernel?

you don't need to remove it from kernel. You can choose which service to run on a machine. A 'terminal' can be configured without running auth service. But you need an auth server when you communicate with other machines.

I want all auth removed.

I hope someone can find a niche for Plan 9, be it on the RPi or somewhere else. So many of its ideas seem to me to be obviously correct in the sense that they logically and conceptually-purely fix the warts other Unix-like OSes have.

Could you expand on that point? While I'm not knowledgeable on the topic I'm genuinely curious to hear a few examples.

I think this says it very well:

http://www.catb.org/esr/writings/taoup/html/plan9.html

>One of the examples from the Plan 9 survey paper is the way FTP access to remote sites is implemented. There is no ftp(1) command under Plan 9. Instead there is an ftpfs fileserver, and each FTP connection looks like a file system mount. ftpfs automatically translates open, read, and write commands on files and directories under the mount point into FTP protocol transactions. Thus, all ordinary file-handling tools such as ls(1), mv(1) and cp(1) simply work, both underneath the FTP mount point and across the boundaries with the rest of the user's view of the namespace. The only difference the user (or his scripts and programs) will notice is retrieval speed.

Short question: What were the downsides to use Plan9 or Inferno as the fundament of a distro insted of Linux? Of course with Linux programms where it would be necessary.

Plan 9 is a complete OS, so things like coreutils are not really necessary (tho plan 9 utilities are not strictly POSIX compatible). The killer app would be a good enough web browser, if you're talking about a workstation OS. Other than that it already has a vast set of utilities, including an extensible text editor (acme), mail, etc. for development work .

It doesn't have glibc or gcc support so the only compiler you have is the non-standard ansc C compiler in Plan 9 (and several efforts to introduce other languages have popped up over time but to my knowledge never took off and required a lot of novel code to make work). This means almost all current software cannot be compiled on Plan9.

So the Linux programs that would be necessary are glibc and gcc, and if you had those you would be able to compile most command line software except for anything that used anything but the standard C library (which would now have been ported to Plan9). Of course, anything accessing most files in a Linux filesystem would break, since Plan9 uses a different layout, and anything that called Linux system calls directly would also break, even UNIX ones, because Plan9 is not Unix.

Going up the stack just makes things worse. You couldn't use any GUI program because you don't have GLX or EGL support for render targets. You don't have OpenGL, so anything written against that can't work.

So you are basically restricted to command line programs that are isolated and make no attempt to use kernel features or arbitrary files in the file system. Even simple things you don't innately think of, like XDG directories, aren't available in a Plan9 environment because its not an X system, so software that uses those won't be able to find the standard config or local cache directories (they will just pull blank envrionment variables and at best write to the current working directory). If you set those variables up manually, you could run stateful software... that didn't use direct Unix system calls.

On the bright side, you could probably get some programming language runtimes to work. Depends on if, say, your Python interpreter uses platform specific system calls or only depends on libc. CPython at least absolutely does have platform specific code paths that would break on Plan9 (because they would assume Unix defaults in the absence of Darwin or NT) but I'm not sure about, say, Pypy. Those runtimes would still be constrained to text only, since the Plan9 graphics layer isn't related to anything in Linux.

Plan9 isn't a kernel, its an operating system in the RMS GNU/Linux sense. Linux distros really depend more in general software on the GNU part than the Linux part, which is both why projects like Debian can drop in Hurd and not have billions of man hours of porting work to do to make it happen and why traditional desktop Linux applications aren't all over Android.

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