Plan 9 from AT&T Bell Labs - Frequently Asked Questions [FAQ]

[Steve Kotsopoulos steve@ecf.toronto.edu]

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Archive-name: Plan9-faq
Last-modified: 7 Sept 1995
Posting-Frequency: monthly
URL: http://www.ecf.toronto.edu/plan9/plan9faq.html

Welcome to comp.os.plan9.

Before we Begin:

This document answers frequently asked questions about the Plan 9 operating
system.

Much of it was taken (with permission) from Dennis Ritchie's Plan 9 Q&A press
release, which was converted to html by Dave Presotto. If you've already seen
that Bell Labs Plan 9 FAQ , you may want to skip straight to the following
sections:

   * How can I Obtain Plan 9?
   * What PC hardware works well with Plan 9?
   * How do I Install Plan 9?
   * Are there any known problems?
   * How do I upgrade from the old release of Plan 9?
   * Is anyone working on a port for my system?
   * What can I do to help?

A hypertext version of this FAQ is available on my Plan 9 web page, URL
http://www.ecf.toronto.edu/plan9/

Most of the links in the html version of this document point to files on the
Plan 9 homepage at Bell Labs, URL http://plan9.att.com/plan9/index.html

This is a preliminary draft of the FAQ, and I'm sure it will evolve quickly now
that comp.os.plan9 has been created. Please forward any comments or suggestions
to steve@ecf.toronto.edu.

This FAQ will be posted to comp.answers and news.answers, once the *.answers
moderators approve it (which may take 4 weeks or so).

Note that when you see sentences written in the first person, it is the Plan 9
developers speaking, not me.

Introduction:

   * What is Plan 9?
   * What is its relation to other operating systems?
   * What are its key ideas?
   * What are the advantages to this approach?

Hardware and Software:

   * What platforms does it run on?
   * Is anyone working on a port for my system?
   * Does it support symmetric multiprocessing?
   * Is it object-oriented?
   * What about applications and tools?
   * What about application portability?
   * What resources does it need?
   * What GUIs does it support?
   * What character set does it use?
   * What about security and user authentication?
   * How does it communicate with other systems?

Installation:

   * What PC hardware works well with Plan 9?
   * How do I Install Plan 9?
   * Are there any known problems?
   * It doesn't work for me, how should I troubleshoot?
   * How do I upgrade from the old release of Plan 9?

General Information:

   * Who is using Plan 9?
   * Where did the name come from?
   * What are the plans for Plan 9?
   * How can I Obtain Plan 9?
   * What can I do to help?
   * How can I get more detailed technical information?

Introduction:

Subject: What is Plan 9?

Plan 9 is a new computer operating system and associated utilities. It has been
built over the past several years by the Computing Science Research Center of
AT&T Bell Laboratories, the same group that developed Unix, C, and C++.

Plan 9 is a distributed system. In the most general configuration, it uses
three kinds of components: terminals that sit on users' desks, file servers
that store permanent data, and other servers that provide faster CPUs, user
authentication, and network gateways. These components are connected by various
kinds of networks, including Ethernet, Datakit, specially-built fiber networks,
ordinary modem connections, and ISDN. In typical use, users interact with
applications that run either on their terminals or on CPU servers, and the
applications get their data from the file servers. The design, however, is
highly configurable; it escapes from specific models of networked workstations
and central machine service.

Subject: What is its relation to other operating systems?

Plan 9 is itself an operating system; it doesn't run as an application under
another system. It was written from the ground up and doesn't include other
people's code. Although the OS's interface to applications is strongly
influenced by the approach of Unix, it's not a replacement for Unix; it is a
new design.

Subject: What are its key ideas?

Plan 9 exploits, as far as possible, three basic technical ideas: first, all
the system objects present themselves as named files that are manipulated by
read/write operations; second, all these files may exist either locally or
remotely, and respond to a standard protocol; third, the file system name space
- the set of objects visible to a program - is dynamically and individually
adjustable for each of the programs running on a particular machine. The first
two of these ideas were foreshadowed in Unix and to a lesser extent in other
systems, while the third is new: it allows a new engineering solution to the
problems of distributed computing and graphics. Plan 9's approach means that
application programs don't need to know where they are running; where, and on
what kind of machine, to run a Plan 9 program is an economic decision that
doesn't affect the construction of the application itself.

Subject: What are the advantages to this approach?

Plan 9's approach improves generality and modularity of application design by
encouraging servers that make any kind of information appear to users and to
applications just like collections of ordinary files. Here are a few examples.

The Plan 9 window system (called 8½) is small and clean in part because its
design is centered on providing a virtual keyboard, mouse, and screen to each
of the applications running under it, while using the real keyboard, mouse, and
screen supplied by the operating system. That is - besides creating, deleting,
and arranging the windows themselves - its job is be a server for certain
resources used by its clients. As a side benefit, this approach means that the
window system can run recursively in one of its windows, or even on another
machine.

Plan 9 users do Internet FTP by starting a local program that makes all the
files on any FTP server (anywhere on the Internet) appear to be local files.
Plan 9 PC users with a DOS/Windows partition on their disk can use the files
stored there. ISO 9660 CD-ROMs and tar and cpio tapes all behave as if they
were native file systems. The complete I/O behavior and performance of any
application can be monitored by running it under a server that sees all its
interactions. The debugger can examine a program on another machine even if it
is running on a different hardware architecture.

Another example is the approach to networks. In Plan 9, each network presents
itself as a set of files for connection creation, I/O, and control. A common
semantic core for the operations is agreed upon, together with a general server
for translating human-readable addresses to network-specific ones. As a result,
applications don't care which kind of network (TCP/IP, ISDN, modem, Datakit)
they are using. In fact, applications don't even know whether the network they
are using is physically attached to the machine the application is running on:
the network interface files can be imported from another machine.

Hardware and Software:

Subject: What platforms does it run on?

The Plan 9 kernel and applications are highly portable. Plan 9 runs on four
major machine architectures: Intel 386/486/Pentium, MIPS, SPARC, and Motorola
68020. Data structures and protocols are designed for distributed computing on
machines of diverse design. Except for necessarily machine-dependent parts of
the kernel, the compilers, and a few libraries, there is a single source
representation for everything.

The systems supported under each architecture are:
386 - 386, 486, Pentium and clones (see the What PC hardware works well with
Plan 9? section of this faq for more information;
MIPS - MIPS Magnum 3000, 6280, SGI Power Series, Indigo, Challenge M;
SPARC - SLC (4/20) Sparcstation 2 (4/75) have been tested, Sparcstation 1
(4/60), IPC (4/40), 1+ (4/65), ELC (4/25), and IPX (4/50) will probably work
too;
68020 - Gnot, 68040 NeXTstation.

More details are available in The Various Ports at URL
http://plan9.att.com/plan9/doc/port.html

Subject: Is anyone working on a port for my system?

The system does not run on an SGI Indy yet, but forsyth will probably get it
working once he has the time.

Neither the Amiga nor Atari are supported.

forsyth ported an older version of Plan 9 to the Sun-3/50 and 3/60. David Hogan
has the new release working on Sun-3/50 and 3/60s. He will make it available
once he tidies it up.

David Hogan is also working on a port to the DEC Alpha architecture. He will
announce it when it is ready.

Subject: Does it support symmetric multiprocessing?

Yes. Our CPU and file servers are both multi-processor machines.

Subject: Is it object-oriented?

No, not in the conventional sense. It is written in a strict dialect of
ISO/ANSI C. In a wider sense, its general design of making all its `objects'
look like files to which one talks in a well-defined protocol shows a related
approach.

Subject: What about applications and tools?

Plan 9 comes with its own compilers for C and other languages, together with
all the commands and program-development tools originally pioneered in the Unix
environment. It also provides newly designed software. Alef is a new language
that provides threads, inter-process and inter-machine communication through
typed channels, and abstract data types. Acid is a programmable debugger that
understands multiple-process programs, and the programs it is debugging may be
running on a hardware platform different from its own. Acme is a new user
interface in which any word on the screen can be interpreted as a command by
clicking on it, and any string can specify a file to be displayed.

Subject: What about application portability?

Plan 9 comes with a library that makes it easy to import POSIX-conforming
applications. There is also a library that emulates the Berkeley socket
interface.

Subject: What resources does it need?

As might be expected, the answer depends on what you want to do. The kernel,
the window system, and the basic applications will run comfortably on a laptop
PC with 8MB of memory. A single diskette can hold the kernel, window system,
editor, and basic Ethernet/Internet interface. A 4-diskette set will hold a
system sufficient for simple program development (compiler, loader, debugger,
more utilities).

On the other hand, the system can grow. Our own installation at AT&T Bell
Laboratories includes multiprocessor SGI Power Series and Challenge machines as
CPU servers, and a 350GB Sony WORM disk jukebox for the file server.

Subject: What GUIs does it support?

The standard interface doesn't use icons; Plan 9 people tend to be
text-oriented. But the window system, the editor, and the general feel are very
mousy, very point-and-click: Plan 9 windows are much more than a bunch of glass
TTYs. The system supports the graphics primitives and libraries of basic
software for building GUIs, and if need arises, the X window system has been
ported to Plan 9. [Note: The X server only runs on MIPS systems. No one at Bell
Labs is working on the port, so they didn't ship it with the CDROM]

Subject: What character set does it use?

The character set is Unicode, the 16-bit set unified with the ISO 10646
standard for representing languages used throughout the world. The system and
its utilities support Unicode using a byte-stream representation (called UTF-8)
that is compatible with ASCII. On Plan 9, one may grep for Cyrillic strings in
a file with a Japanese name and see the results appear correctly on the
terminal.

Subject: What about security and user authentication?

Plan 9's authentication design is akin to that of MIT's Kerberos. Passwords are
never sent over networks; instead encrypted tickets are obtained from an
authentication server. It doesn't have the concept of `set UID' programs. The
file server doesn't run user programs, and except at its own console, it
doesn't allow access to protected files except by authenticated owners. The
concept of a special `root' user is gone.

Subject: How does it communicate with other systems?

The distribution includes a server that runs on Unix-compatible systems and
understands the native Plan 9 remote file protocol, so that file systems of
Unix machines may be imported into Plan 9. It also includes an NFS-compatible
server that runs on Plan 9, so that Plan 9 file systems may be accessed from
other systems that support NFS. It includes the full suite of Internet
protocols.

Installation:

Subject: What PC hardware works well with Plan 9?

If you don't want to spend time fiddling with and swapping PC hardware, you may
prefer to buy hardware that is in use within Bell Labs. If so, have a look at
the What We Use document by jmk@plan9.att.com, at
http://www.ecf.toronto.edu/plan9/clone.html

Recently, jmk@plan9.att.com wrote:
Subject: re: PC-clone hardware
This is a little out of my experience, but if I had to buy a 486 motherboard
I'd look for one that would take a DX4-100 and even one of the new Cyrix M1sc
chips (i.e. handles 3.3V CPUs). Plus I'd opt for a PCI+ISA board with I/O on
the motherboard (I think only AIR makes a 486 MB with PCI+EISA). SIS or Intel
chipset should be OK.
Our only other experience with 486 motherboards has been Micronics in some old
Gateways. There have been troubles there with the Phoenix BIOS and accessing
the BIOS ROM areas from Plan 9, but that's probably because we don't make any
attempt to work out the 8/16-bit BIOS stuff.

If you have time for netnews, the OS/2 and Linux newsgroups probably have some
useful information.

Another useful web page on PC hardware (with a BSDi bias) is PC Hardware Hints
and Kinks at http://www.vix.com/pc-hw/

Subject: How do I Install Plan 9?

The installation is designed to be run from a PC. Note that Plan 9 uses an
unallocated portion at the end of the disk, and you won't see this partition
with the FDISK program.
  1.  Back up your system.
  2.  Make sure you've backed up your system.
  3.  Read Installing the Plan 9 Distribution at URL
     http://plan9.att.com/plan9/doc/install.html
  4.  Check the errata page (at http://plan9.att.com/plan9/errata.html) for
     problems and fixes found since the distribution was frozen.
  5.  Here are some more tips that have been reported to the 9fans list:
     Subject: three button mice
     From: forsyth@plan9.cs.york.ac.uk

     aux/mouse -dC $mouseport

     usually does the trick. many three button mice do not respond to
     aux/mouse's guessing protocol, but you can tell it what to use as the
     default. on starting the demonstration system, answer `n' when the system
     asks if you want to enter the window system. once you type the aux/mouse
     command above, you should be able to move the mouse. you can then enter
     the window system and enjoy yourself. (while you're there, you can change
     /rc/bin/termrc to add the -dC option to the aux/mouse commands there.) of
     course, if you still can't move the mouse, you'll need to try another
     default.

     -d isn't documented in the manual page, but that fact is documented
     somewhere (i can't find it now). perhaps it was in the Errata.

Subject: Are there any known problems?

From: jmk@plan9.att.com
To: 9fans@cse.psu.edu
Date: Sat, 2 Sep 1995 10:14:51 -0400
Subject: fixes in the works

We have fixes in the works (with help from others) for the floppy disc read and
Adaptec 1542CF timeout problems. These will hopefully be available for pick-up
by ftp by this time next week. Source updates based on diffs to the
distribution source should also start appearing soon.

The hard disc partitioning problem will take longer to fix, but I've started
working on it. Unfortunately it means doing a crash-course in booting OS/2 and
Linux.

Subject: It doesn't work for me, how should I troubleshoot?

From: prb@bsdi.COM (Paul Borman)
The first three things to do when having SCSI problems:

1) Check your cables and terminators
2) Check your cables and terminators
3) Check your cables and terminators

We have found under BSD/OS that this is the single largest cause of weird SCSI
problems. Active terminators are best. If you run external cables you need to
get high quality ones. We did discover that with adaptec and poorer quality
terminators (like the ones that come on most disk drives) that if you had an
internal and external chain that you had to leave the terminators in the card
(so you would have 3 sets). This is clearly wrong, but it is what it took for
some combinations. Also, don't crank of the speed on the card.

Subject: How do I upgrade from the old release of Plan 9?

The 9P protocol has changed in the second edition, due to changes in the way
that Plan 9 does its authentication. For those using Unix-based (u9fs) file
servers, you will have to compile and install the new version of u9fs.

For those using the standard Plan 9 file servers, ken@plan9.att.com reports
that the disk format in the new release is the same, so there should be no
problems running the new FS code on old disks.

General Information:

Subject: Who is using Plan 9?

[this section could use some more work - Steve]

The first (1993) release of Plan 9 was licenced by 200 colleges and
universities.

With the public release of Plan 9 and the free demo PC version, many people who
were not able to use the old version of Plan 9 are now using it. The number of
copies sold is not known yet.

There is exploratory use in commercial companies, both within AT&T and outside.
Most visibly, the Netlib service that supplies mathematical and other software
and documents to the public via FTP, mail, and WWW uses a Plan 9 server. This
service includes the AT&T 800-number directory by which WWW users can find the
toll-free numbers of AT&T 800-number advertisers.

Subject: Where did the name come from?

It was chosen in our tradition of selecting names that make marketeers wince.
We also wished to pay homage to the famous film, Plan 9 From Outer Space.

Subject: What are the plans for Plan 9?

Plan 9 was developed within the research organization of AT&T Bell Laboratories
as an exercise in understanding the principles and mechanisms useful in
designing operating systems, and not as a product as such. In this way it is
analogous to the Unix efforts of the past. Nevertheless, to succeed, it must be
used, both within our company and outside. We believe that making it more
generally available under reasonable terms will enhance its impact, and have
been working with the AT&T Software Solutions group to find the best ways of
doing this. A general distribution of the technology for non-commercial
purposes is available, and we would like to license it for commercial purposes
on terms to be negotiated. Just as in the early stages of deployment of Unix,
these arrangements will be `as-is,' with no support promised.

Current plans call for this distribution to consist of a CD-ROM containing the
entire source and binary for all platforms, a two-volume manual set, and four
diskettes. The diskettes contain a binary-only version of the system that can
be installed on a PC to demonstrate the window system, many of the applications
including Internet communications, and the Intel-architecture C and Alef
compilers.

Subject: How can I Obtain Plan 9?

Complete information for purchasing the Plan 9 distribution or ftp'ing the free
PC trial version is available at URL http://plan9.att.com/plan9/distrib.html

Any bookshop should be able to order it for you, if you give them one of the
ISBN numbers listed on that page.

To find out whether Plan 9 supports your hardware, read The Various Ports at
URL http://plan9.att.com/plan9/doc/port.html

Subject: What can I do to help?

The best way to help is to write something that other people in the Plan 9 user
community could use, or to port the system to new platforms. Several people
have already made their applications available, such as an http server,
fileserver port to the PC, etc. The current list of user-community projects
includes:

pace@blitz.com (Pace Willisson) has ported the Plan 9 authentication server to
Unix, to allow Plan 9 terminals to function without a Plan 9 cpu server
performing authentication. He wrote:
The basic idea is that I wrote a SOCK_RAW based IL driver, and then imported
the main parts of the plan 9 auth.srv program. You probably don't need this
unless you have at least 3 computers: a unix system that you have to keep
running even when playing with plan 9, plus 2 other computers to run a plan 9
file server and a plan 9 terminal.
If you would like to receive a copy of this program, please send email to
stating that:

you are a plan 9 licensee
you are a United States citizen
your email is delivered in the United States

I'll send a uuencoded, gzipped tar file by return email. To international
users, I apologize for the silly US export rules, but I don't know what else I
can do.

Pace later added:
I've separated the encryption stuff from my IL driver, and put the exportable
parts up for anonymous ftp at
ftp://ftp.blitz.com/pub/il.tar.gz

If anyone would like their projects listed here, let me know. This could help
prevent duplication of effort, and increase involvment from the 'net community.

Subject: How can I get more detailed technical information?

The Internet site plan9.att.com stores a collection of papers about the system
in the plan9 directory; they are available for anonymous FTP.

Copyright © 1995 AT&T. All rights reserved.
-- 
Steve Kotsopoulos  P.Eng.                         steve@ecf.toronto.edu
Systems Analyst,  Engineering Computing Facility, University of Toronto
http://www.ecf.toronto.edu/staff/steve/