4 Jan
2017
4 Jan
'17
2:54 a.m.
Peter Salus writes "The other innovation present in the Third Edition
was the pipe" ("A Quarter Century of Unix", p. 50). Yet, in the
corresponding sys/ken/sysent.c, the pipe system call seems to be a stump.
1, &fpe, /* 40 = fpe */
0, &dup, /* 41 = dup */
0, &nosys, /* 42 = pipe */
1, ×, /* 43 = times */
On the other hand, the Fourth Edition manual documents the pipe system
call, the construction of pipelines through the shell, and the use of wc
as a filter (without an input file, as was required in the Second Edition).
Would it therefore be correct to say that pipes were introduced in the
Fourth rather than the Third Edition?
4 Jan
4 Jan
3:50 a.m.
Hmm.. it's all about where you count. Clearly, he was working on it if
the stubs is there. If the only difference between 3rd and 4th is the pipe
code, then it would be fair to say that.
You might say something like: Pipe's were developed in a 3rd edition
kernel, where there was is evidence of nascent idea (its has a name and
there are subs for it), but the code to fully support it is lacking in the
3rd release. Pipes became a completed feature in the 4th edition.
On Tue, Jan 3, 2017 at 3:54 PM, Diomidis Spinellis <dds(a)aueb.gr> wrote:
Peter Salus writes "The other innovation present
in the Third Edition was
the pipe" ("A Quarter Century of Unix", p. 50). Yet, in the
corresponding
sys/ken/sysent.c, the pipe system call seems to be a stump.
1, &fpe, /* 40 = fpe */
0, &dup, /* 41 = dup */
0, &nosys, /* 42 = pipe */
1, ×, /* 43 = times */
On the other hand, the Fourth Edition manual documents the pipe system
call, the construction of pipelines through the shell, and the use of wc as
a filter (without an input file, as was required in the Second Edition).
Would it therefore be correct to say that pipes were introduced in the
Fourth rather than the Third Edition?
3:53 a.m.
On Tue, Jan 03, 2017 at 10:54:57PM +0200, Diomidis Spinellis wrote:
Peter Salus writes "The other innovation present
in the Third Edition was
the pipe" ("A Quarter Century of Unix", p. 50). Yet, in the
corresponding
sys/ken/sysent.c, the pipe system call seems to be a stump.
The Third edition was still written in assembly code. The Fourth edition
was the first to be rewritten in C. So there was a time when both
existed in parallel.
1, &fpe, /* 40 =
fpe */
0, &dup, /* 41 = dup */
0, &nosys, /* 42 = pipe */
1, ×, /* 43 = times */
This code, from the nsys kernel, clearly shows this. The kernel was
being rewritten in C. The C version had not yet caught up with the
functionality in the assembly version of the kernel, which did have pipes.
Cheers, Warren
4:04 a.m.
On Wed, Jan 04, 2017 at 07:53:10AM +1000, Warren Toomey wrote:
The Third edition was still written in assembly code.
The Fourth edition
was the first to be rewritten in C. So there was a time when both
existed in parallel.
I should have waited to add this. The nsys kernel is dated August 31, 1973 (see
http://www.tuhs.org/Archive/PDP-11/Distributions/research/Dennis_v3/Readme.…)
and the Third Edition manuals are dated February 1973 (see
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V3/man/man0/intro)
The 3e manuals have a pipe syscall:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V3/man/man2/pipe.2
so pipes existed in February 1973. In fact, they existed as early as
January 15, 1973, as Doug McIlroy put out the notice for a talk which
described the state of UNIX at that time; page 4 describes SYS PIPE and its
implementation, (see
http://www.tuhs.org/Archive/Documentation/Papers/Unix_Users_Talk_Notes_Jan7…)
Interestingly, the pipe manpage says:
SYNOPSIS sys pipe / pipe = 42.; not in assembler
and I don't quite understand the comment :-) Other manpages with
the same comment are boot(2), csw(2), fpe(2), kill(2), rele(2), sleep(2),
sync(2) and times(2). So it's not particular to pipe(2).
Can anybody help explain the "not in assembler" comment?
Thanks, Warren
4:20 a.m.
Can anybody help explain the "not in
assembler" comment?
In early 'as' some syscall mnemonics were predefined, see for instance:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/as/as29.s
'pipe' isn't one of those.
Paul
5 Jan
5 Jan
6:51 a.m.
On Wed, 4 Jan 2017, Warren Toomey wrote:
Interestingly, the pipe manpage says:
SYNOPSIS sys pipe / pipe = 42.; not in assembler
and I don't quite understand the comment :-) Other manpages with
the same comment are boot(2), csw(2), fpe(2), kill(2), rele(2), sleep(2),
sync(2) and times(2). So it's not particular to pipe(2).
Can anybody help explain the "not in assembler" comment?
As I recall, it means that those symbols are not recognised by the
assembler, so had to be defined by hand.
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will
suffer."
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5 comments
5 participants
participants (5)
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Clem Cole -
Dave Horsfall -
Diomidis Spinellis -
Paul Ruizendaal -
Warren Toomey