[TUHS] Shell control through external commands

Norman Wilson norman at oclsc.org
Mon Sep 12 11:31:10 AEST 2016

Doug McIlroy:

  "Re-port" may be a bit strong. Internet stuff from Berkeley
  was folded into the research code (for a huge increase in
  kernel size). But I think it was done by pasting Berkeley
  code into local source, rather than the other way around.


Actually it was more nearly:

-- Adopt 4.1c BSD kernel
-- Graft in Research-specific things it was important to
keep: in particular Dennis's stream subsystem, Tom Killian's
original /proc, Peter Weinberger's early network file system
client code (the server was just a user-mode program) and
simple hackery to speed up the file system without great
fuss (make the block size 4KiB and move the free list to
a bitmap; no cylinder groups or other radical changes).
Also device drivers to support Datakit, at the time our
workhorse network.  I think a file-system switch went
in early as well, spurred by having both /proc and
pjw's network file system; it wasn't used to support
multiple disk-file-system layouts, though it could have
-- Outside the kernel, keep pretty much the then-current
Research commands, including Blit/5620 support, the
cleaned up and slightly-extended Bourne shell, and whatnot.

I don't think the BSD kernel when adopted had much, if any,
of sockets, Berkeley's TCP/IP, McKusick's FFS; if it did,
they were excised.  Likewise any remaining trace of V7's
mpx(2) multiplexed-file IPC.

I'm going by the state the system was in when I arrived
in August 1984, plus a short note written by Weinberger
that I came across later.

TCP/IP support didn't show up until later, I think summer
1985, though it might have been a year later.  The first
cut was done by Robert T. Morris (later famous for a buggy
program that broke the Internet), who did several summers
as an intern; he took the code from (I think) 4.2 BSD,
and constructed some shims to fit it into the stream world.
Paul Glick later cleaned it up a lot, removing the need
for most of the shimmery.

Further evolution followed, of course, including a
complete rewrite of the interface between drivers
(device, file system, and stream) and the rest of the
system, which made configuration much more straightforward.
Also a rampage on my part to identify code that was no
longer useful and kick it out; I took special pleasure
in removing ptrace(2) (even though I had to change adb
and sdb first to use /proc).

But that was all later.

Norman Wilson
Toronto ON

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