beyond43.ms

早期freebsd实现

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.\"	@(#)beyond43.ms	5.1 (Berkeley) 6/5/90
.\"
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.ce 100
\fB\s+2Current Research by
The Computer Systems Research Group
of Berkeley\s-2\fP
.ds DT "February 10, 1989
.\" \fBDRAFT of \*(DT\fP
.sp 2
.nf
Marshall Kirk McKusick
Michael J Karels
Keith Sklower
Kevin Fall
Marc Teitelbaum
Keith Bostic
.fi
.sp 2
.ce 1
\fISummary\fP
.ce 0
.PP
The release of 4.3BSD in April of 1986 addressed many of the 
performance problems and unfinished interfaces
present in 4.2BSD [Leffler84] [McKusick85].
The Computer Systems Research Group at Berkeley
has now embarked on a new development phase to
update other major components of the system, as well as to offer
new functionality.
There are five major ongoing projects.
The first is to develop an OSI network protocol suite and to integrate
existing ISO applications into Berkeley UNIX.
The second is to develop and support an interface compliant with the
P1003.1 POSIX standard recently approved by the IEEE.
The third is to refine the TCP/IP networking to improve
its performance and limit congestion on slow and/or lossy networks.
The fourth is to provide a standard interface to file systems
so that multiple local and remote file systems can be supported,
much as multiple networking protocols are supported by 4.3BSD.
The fifth is to evaluate alternate access control mechanisms and
audit the existing security features of the system, particularly
with respect to network services.
Other areas of work include multi-architecture support, 
a general purpose kernel memory allocator, disk labels, and
extensions to the 4.2BSD fast filesystem.
.PP
We are planning to finish implementation prototypes for each of the
five main areas of work over the next year, and provide an informal
test release sometime next year for interested developers.
After incorporating feedback and refinements from the testers,
they will appear in the next full Berkeley release, which is typically
made about a year after the test release.
.br
.ne 10
.sp 2
.NH
Recently Completed Projects
.PP
There have been several changes in the system that were included
in the recent 4.3BSD Tahoe release.
.NH 2
Multi-architecture support
.PP
Support has been added for the DEC VAX 8600/8650, VAX 8200/8250, 
MicroVAXII and MicroVAXIII.
.PP
The largest change has been the incorporation of support for the first
non-VAX processor, the CCI Power 6/32 and 6/32SX.  (This addition also
supports the
Harris HCX-7 and HCX-9, as well as the Sperry 7000/40 and ICL machines.)
The Power 6 version of 4.3BSD is largely based on the compilers and
device drivers done for CCI's 4.2BSD UNIX,
and is otherwise similar to the VAX release of 4.3BSD.
The entire source tree, including all kernel and user-level sources,
has been merged using a structure that will easily accommodate the addition
of other processor families.  A MIPS R2000 has been donated to us,
making the MIPS architecture a likely candidate for inclusion into a future
BSD release.
.NH 2
Kernel Memory Allocator
.PP
The 4.3BSD UNIX kernel used 10 different memory allocation mechanisms,
each designed for the particular needs of the utilizing subsystem.
These mechanisms have been replaced by a general purpose dynamic
memory allocator that can be used by all of the kernel subsystems.
The design of this allocator takes advantage of known memory usage
patterns in the UNIX kernel and a hybrid strategy that is time-efficient
for small allocations and space-efficient for large allocations.
This allocator replaces the multiple memory allocation interfaces 
with a single easy-to-program interface,
results in more efficient use of global memory by eliminating
partitioned and specialized memory pools,
and is quick enough (approximately 15 VAX instructions) that no
performance loss is observed relative to the current implementations.
[McKusick88].
.NH 2
Disk Labels
.PP
During the work on the CCI machine,
it became obvious that disk geometry and filesystem layout information
must be stored on each disk in a pack label.
Disk labels were implemented for the CCI disks and for the most common
types of disk controllers on the VAX.
A utility was written to create and maintain the disk information,
and other user-level programs that use such information now obtain
it from the disk label.
The use of this facility has allowed improvements in the file system's
knowledge of irregular disk geometries such as track-to-track skew.
.NH 2
Fat Fast File System
.PP
The 4.2 fast file sytem [McKusick84]
contained several statically sized structures,
imposing limits on the number of cylinders per cylinder group,
inodes per cylinder group,
and number of distinguished rotational positions.
The new ``fat'' filesystem allows these limits to be set at filesystem
creation time.
Old kernels will treat the new filesystems as read-only,
and new kernels
will accomodate both formats.
The filesystem check facility, \fCfsck\fP, has also been modified to check
either type.
.br
.ne 10
.sp 2
.NH
Current UNIX Research at Berkeley
.PP
Since the release of 4.3BSD in mid 1986,
we have begun work on several new major areas of research.
Our goal is to apply leading edge research ideas into a stable
and reliable implementation that solves current problems in
operating systems development.
.NH 2
OSI network protocol development
.PP
The network architecture of 4.2BSD was designed to accommodate
multiple network protocol families and address formats,
and an implementation of the ISO OSI network protocols
should enter into this framework without much difficulty.
We plan to 
implement the OSI connectionless internet protocol (CLNP),
and device drivers for X.25, 802.3, and possibly 802.5 interfaces, and
to integrate these with an OSI transport class 4 (TP-4) implementation.
We will also incorporate into the Berkeley Software Distribution an
updated ISO Development Environment (ISODE)
featuring International Standard (IS) versions of utilities.
ISODE implements the session and presentation layers of the OSI protocol suite,
and will include an implementation of the file transfer protocol (FTAM).
It is also possible that an X.400 implementation now being done at
University College, London and the University of Nottingham
will be available for testing and distribution.  
.LP
This implementation is comprised of four areas.
.IP 1)
We are updating the University of
Wisconsin TP-4 to match GOSIP requirements.
The University of Wisconsin developed a transport class 4
implementation for the 4.2BSD kernel under contract to Mitre.
This implementation must be updated to reflect the National Institute
of Standards and Technology (NIST, formerly NBS) workshop agreements,
GOSIP, and 4.3BSD requirements.
We will make this TP-4 operate with an OSI IP,
as the original implementation was built to run over the DoD IP.
.IP 2)
A kernel version of the OSI IP and ES-IS protocols must be produced.
We will implement the kernel version of these protocols.
.IP 3)
The required device drivers need to be integrated into a BSD kernel.
4.3BSD has existing device drivers for many ethernet devices; future
BSD versions may also support X.25 devices as well as token ring
networks.
These device drivers must be integrated
into the kernel OSI protocol implementations.
.IP 4)
The existing OSINET interoperability test network is available so 
that the interoperability of the ISODE and BSD kernel protocols
can be established through tests with several vendors.
Testing is crucial because an openly available version of GOSIP protocols
that does not interoperate with DEC, IBM, SUN, ICL, HIS, and other
major vendors would be embarrassing.
To allow testing of the integrated pieces the most desirable
approach is to provide access to OSINET at UCB.
A second approach is to do the interoperability testing at
the site of an existing OSINET member, such as the NBS.
.NH 2
Compliance with POSIX 1003
.PP
Berkeley became involved several months ago in the development
of the IEEE POSIX P1003.1 system interface standard.
Since then, we have been parcipating in the working groups
of P1003.2 (shell and application utility interface),
P1003.6 (security), P1003.7 (system administration), and P1003.8
(networking).
.PP
The IEEE published the POSIX P1003.1 standard in late 1988.
POSIX related changes to the BSD system have included a new terminal
driver, support for POSIX sessions and job control, expanded signal
functionality, restructured directory access routines, and new set-user
and set-group id facilities.
We currently have a prototype implementation of the
POSIX driver with extensions to provide binary compatibility with
applications developed for the old Berkeley terminal driver.
We also have a prototype implementation of the 4.2BSD-based POSIX
job control facility.
.PP
The P1003.2 draft is currently being voted on by the IEEE
P1003.2 balloting group.
Berkeley is particularly interested in the results of this standard,
as it will profoundly influence the user environment.
The other groups are in comparatively early phases, with drafts
coming to ballot sometime in the 90's.
Berkeley will continue to participate in these groups, and
move in the near future toward a P1003.1 and P1003.2 compliant
system.
We have many of the utilities outlined in the current P1003.2 draft
already implemented, and have other parties willing to contribute
additional implementations.
.NH 2
Improvements to the TCP/IP Networking Protocols
.PP
The Internet and the Berkeley collection of local-area networks
have both grown at high rates in the last year.
The Bay Area Regional Research Network (BARRNet),
connecting several UC campuses, Stanford and NASA-Ames