1 .HTML "Plan 9 — Third Edition Release Notes
12 Copyright © 2000 Lucent Technologies Inc.
17 The third release of the Plan 9 operating system from Bell Labs
18 is something of a snapshot of the current system.
19 This differs from the previous, 1995 release,
20 which was a more coordinated, well-defined release of an already-out-of-date
22 Also, the previous releases were distributed on fixed media, while this release
23 is being done over the web.
24 The other major difference is that the third release is licensed under
25 an open source agreement, which we hope will encourage people
26 to experiment with it.
28 Beyond that, there are innumerable little changes throughout the code.
29 Although superficially it is the same environment, there is hardly an aspect
30 of the system that has not been redesigned, rewritten, or replaced.
31 The following is an incomplete list of changes.
37 The list of architectures has changed; more compilers are included
38 and the list of kernels has changed.
39 There is solid support for Intel x86 multiprocessors.
40 Also, although the sources are available for
41 other architectures, the binaries and libraries are built only for the
42 Intel x86 architectures.
43 Kernel source is available for x86, Mips, DEC Alpha, and Power PC architectures.
44 Compilers also exist for AMD 29000, Motorola MC68000 and MC68020,
45 Intel i960, and SPARC.
46 (Unlike the the last release, no SPARC kernel exists for the current system.)
47 The compilers and related tools
48 have been made easier to port to Unix and Windows.
50 The kernel now has a file cache to improve I/O performance.
51 Other kernel changes include the replacement of the streams interface
52 with a simpler, faster, but less flexible I/O queue structure.
53 The x86 kernels support PCI and PCMCIA devices.
55 Network management has been simplified and generalized.
56 DNS supports a resolver mode and the DNS server is now solid.
57 DHCP is supported both at the client and server ends.
58 The system can handle multiple IP stacks, which are also
59 no longer Ethernet-specific.
61 The organization of disks in the kernel has been unified, providing
62 a consistent interface to all disks and controllers: SCSI or ATAPI,
65 File offsets, such as in the
67 system call, are now 64-bit values.
68 The 1995 release defined the type
83 which is the wrong byte order.
84 Now, for all architectures,
90 type, although for compatibility it's still held in a union:
98 The kernel now maintains a file name associated with each open file or
99 directory, which can be cheaply recovered by the
102 Plan 9 now does a much better job with
105 On a related note, a description of a process's name space may be
114 The security model is the same, although
115 the key format has changed.
116 If you have an old key file, use
121 There are new libraries for mulitprecision arithmetic and security.
123 The graphics model is very different.
124 It is based on the Porter-Duff compositing algebra rather than
126 and the system supports everything from bitmaps to true-color displays.
127 Some of the graphics drivers exploit hardware acceleration.
129 Coupled to the graphics changes, the image and font file formats have
131 They can represent a wider range of pixel formats and compress the data.
132 Also the white/black sense of value is reversed (zero is now black; pixels
133 represent light, not ink).
134 Most of the tools can handle the old format, but they all write the new format only.
136 The user interface now incorporates plumbing, a language-driven
137 way for applications to communicate. See
141 Building on plumbing and a program that presents the mail box as a file
142 system, Plan 9 now has convenient support for MIME mail messages.
147 which has a similar appearance but a different architecture.
148 Although still a file server, it is much more efficient: the kernel driver
149 multiplexes graphics output so
151 is not in the display path.
153 handles input and window control only.
155 PC booting is more sophisticated. PCs can now boot Plan 9 directly from
156 the disk without running DOS.
159 It was deemed too difficult to maintain two sets of compilers and libraries
160 for all architectures.
161 Alef programs were translated into C, with the help of a new thread library
162 that preserves much of Alef's functionality, but none of its syntax.
164 Mothra is gone. There is no web browser included in this release,
165 but something may well appear before long.
169 (frame buffer) suite is gone. Most of its tools are
170 supplanted by new ones, such as
176 Also gone from this release are the games and support for
182 New things include an implementation of
185 and some spam-filtering software (see
189 If you have problems, mail
190 .CW 9trouble@plan9.bell-labs.com .
191 Please don't mail us individually.