TUHS

tuhs@tuhs.org

33 participants
6541 discussions

mmap origin (was Systematic approach to command-line interfaces)

by Paul Ruizendaal

On Wed, Sep 29, 2021 at 09:40:23AM -0700, Greg A. Woods wrote: > I think perhaps the problem was that mmap() came too soon in a narrow > sub-set of the Unix implementations that were around at the time, when > many couldn't support it well (especially on 32-bit systems -- it really > only becomes universally useful with either segments or 64-bit and > larger address spaces). The fracturing of "unix" standards at the time > didn't help either. > > Perhaps these "add-on hack" problems are the reason so many people think > fondly of the good old Unix versions where everything was still coming > from a few good minds that could work together to build a cohesive > design. The add-ons were poorly done, not widely implemented, and > usually incompatible with each other when they were adopted by > additional implementations. mmap() did come from those days and minds. The first appearance of mmap() was in 32V R3, done by John Reiser in 1981. This is the version of 32V with full demand paging; it implemented a unified buffer cache. According to John, that version of mmap() already had the modern 6 argument API. John added mmap() because he worked with Tenex a lot during his PhD days and missed PMAP. He needed some 6 months to design, implement and debug this version of 32V as a skunkworks project. I am trying to revert early VAX SVr1/r2 code to get a better view of what 32V R3 looked like, but unfortunately I did not have much time for this effort in last couple of months. It would seem that 32V R3 assumed that disk blocks and memory pages were the same size (true on a 1980 VAX) and with that assumption a unified buffer cache comes natural in this code base. For 4.2BSD initially Joy cs. had a different approach to memory mapped files in mind (see the 1981 tech report #4 from CSRG). By the time of 4.2BSD’s release the manual defined a mmap() system call, but it was not implemented and it appears to have been largely forgotten until SunOS 4 and dynamic libraries six years later. In the SysV lineage it is less clear. For sure mmap() is not there, but the first implementation of the shmem IPC feature might derive from the 32V R3 code. On the inside, SVr2 virtual memory appears to implement the segments (now called regions) that Joy envisaged for 4.2BSD but did not implement. CB Unix had a precursor to shmem as well, where a portion of system core was reserved for shared memory purposes and could be accessed either via the /dev/mem device or could be mapped into the PDP-11 address space (using 1 of the 8 segment registers for each map). Here too the device and the map were unified. So far, I have not come across any shared library implementations or precursors in early Unix prior to SunOS 4. Paul

3 years, 9 months

IEEE Annals on the History of Computing seeks Editor in Chief

by Diomidis Spinellis

Dear TUHS members, The IEEE Annals on the History of Computing magazine, the primary publication for recording, analyzing, and debating the history of computing, is seeking a new Editor in Chief [2]. The EiC term begins on January 1st 2022 and is for three years, renewable for two years. The application deadline is October 31st 2021. It would be valuable for us interested in our discipline's history to to serve in the publication's leadership. You can contact Carrie Clark at c.clark(a)computer.org to submit an application. Alternatively, if you have connections in the community and some time to spare to head the EiC selection committee, please drop me a note. [1] https://www.computer.org/csdl/magazine/an [2] https://www.computer.org/press-room/2021-news/ieee-cs-publications-seek-app… Kind regards, Diomidis Spinellis

3 years, 9 months

RIP Jörg Schilling

by Robert Clausecker

I have received message from his family that Jörg Schilling has passed away from complications related to kidney cancer this sunday around noon (CEST). He will be remembered for his open source projects including - cdrtools, the first portable CD burning program - star, a powerful and fast tar implementation, the first to use two processes with a shared ring buffer for better performance. - smake, a make implementation with autoconf features - sformat, a versatile SCSI disk formatting program - SING, an autoconf fork with a comprehensive set of libc shims, providing a uniform API across operating systems - ved, an early visual editor for the UNOS operating system (I believe) - bosh, a carefully maintained fork of the Bourne shell - sccs, a carefully maintained fork of SCCS. His attempts to teach it projects and networking will remain unfinished. - libfind, an implementation of find(1) as a library for integration into other software. - libxtermcap, an extended termcap library - libscg, an early portable SCSI driver and library He is also remembered for his commitment to open source, portability, and his work on POSIX. He was working on adapting his software to Z/OS and introducing message catalogues just weeks before his death. Jörg worked for the Bethold typesetting company, one of the first European customers of SUN microsystems. It is there that his love for UNIX and SUN OS in particular was kindled. [1] His interest in SUN OS culminated in Schillix, one of the first open source Solaris distributions. We will of course also remember him for his flames. [1]: https://web.archive.org/web/20061201103910/http://www.opensolaris.org/os/ar… May his software immortalise him. Robert Clausecker -- () ascii ribbon campaign - for an 8-bit clean world /\ - against html email - against proprietary attachments

3 years, 9 months

Re: [TUHS] [Haskell-cafe] Terminator syntax style (Was: Nested (=>) (Was: On finding the right exposition...))

by Norman Wilson

John Cowan: "Between each" has been part of Standard English for a thousand years, and still is today. ==== As in between each pair of elements, or between each element? The latter strikes me rather like the currently-in-vogue phrase `one of the only': it may have a defined meaning, but it sure sounds distractingly stupid. (If it's one of the group at all, it's by definition one of the only members; if what is meant is one of the few, then say so, dammit.) It's rather like obfuscated C, or nearly any use of Perl: sure, you can write it to require extra mental effort to make sense of it, but there are simpler ways to be rude. Norman Wilson Toronto ON Please, sir, I'd like to join The Few. I'm sorry, there are far too many.

3 years, 9 months

Re: [TUHS] [Haskell-cafe] Terminator syntax style (Was: Nested (=>) (Was: On finding the right exposition...))

by Douglas McIlroy

Apropos of "finding the right exposition"!, consider the cited wiki article: Separator: There is a symbol between each element. The more carefully you read this the more it becomes nonsense. 1, "Each element" is an individual. You can't put something between an individual. 2 The defining sentence states a property of a representation of a sequence. It fails to indicate that "separator" is the symbol's role. In fact what's being defined is "separator notation", not the bare word "separator". This usage appears only later in the article. It should be employed throughout--most importantly in the title and the definition. The same goes for "terminator". Doug

3 years, 9 months

retraction

by Douglas McIlroy

> Doug, if you insist on applying your superb editing skills on wiki material, we will never hear from you again! Thanks, Bill, for the wise advice. If I'm putting out stuff like this you shouldn't hear from me again. Apologies for again(!) posting to the wrong mailing list. Doug

3 years, 9 months

4.3BSD-Tahoe Restoration

by Henry Bent

Hello All, I am attempting to restore 4.3BSD-Tahoe to a usable state on the VAX. It appears, based on the work that I have done already, that this is possible. Starting with stock 4.3BSD I got a source tree into /usr/tahoe and using it I replaced all of /usr/include and /sys, recompiled and replaced /bin, /lib, and /etc, recompiled a GENERIC kernel, and from there I was able to successfully reboot using the new kernel. As far as I can tell (fingers crossed!) the hardest part is over and I'm in the process of working on /usr. My question is: how was this sort of thing done in the real world? If I was a site running stock 4.3BSD, would I have received (or been able to request) updated tapes at regular intervals? The replacement process that I have been using is fairly labor intensive and on a real VAX would have been very time intensive too. Fortunately two to three years' worth of changes were not so drastic that I ever found myself in a position where the existing tools were not able to compile pieces of Tahoe that I needed to proceed, but I could easily imagine finding myself in such a place. (This was, by the way, what I ran into when attempting to upgrade from 2.9BSD to 2.10BSD, despite a fully documented contemporary upgrade procedure). -Henry

3 years, 9 months

Groups origins

by norman＠oclsc.org

I can't speak to the evolution and use of specific groups; I suspect it was all ad-hoc early on. Groups appeared surprisingly late (given how familiar they seem now): they don't show up in the manual until the Sixth Edition. Before that, chown took only two arguments (filename and owner), and permission modes had three bits fewer. I forget how it came up, but the late Lee McMahon once told me an amusing story about their origin: Ken announced that he was adding groups. Lee asked what they were for. Ken replied with a shrug and `I dunno.' Norman Wilson Toronto ON

3 years, 9 months

Groups origins

by norman＠oclsc.org

Groups appeared surprisingly late (given how familiar they seem now): they don't show up in the manual until the Sixth Edition. Mea culpa; read too hastily. The change actually came with the Fourth Edition, at the same time as several other landmark system changes: -- Time changing from a 32-bit count of 60Hz clock ticks (which ran out so quickly that its epoch kept moving) to the modern 32 bits of whole seconds, based at 1970-01-01T00:00:00 GMT (which takes much longer to run out, though the horizon is now visible). -- The modern super-block. In 4/e, the super-block began at block 0, not 1 (so bootstrapping was rather more complicated); the free list was a bitmap rather than the later list of blocks containing lists of free block numbers. -- The super-block contained a bitmap of free i-numbers too. All told, the free block and free i-node map made up a 1024-byte super-block. -- I-numbers 1-40 were device files; the root directory was i-number 41. The only file-type indication in the mode word was a single bit to denote directory. It was already clear that the lifetime of the bitmaps was running out: the BUGS section says two blocks isn't enough for the bitmaps for a 20-megabyte RP02. Norman Wilson Toronto ON

3 years, 9 months

Groups origins

by Will Senn

Hi all, I was reading a recent thread, over on the FreeBSD forums about groups that quickly devolved into a discussion on the origin of the operator group: https://forums.freebsd.org/threads/groups-overview.82303/ I thought y’all would be the best place to ask the questions that arose in me during my read of the thread. Here they are in no special order: 1. Where did operator come from and what was it intended to solve? 2. How has it evolved. 3. What’s a good place to look/ref to read about groups, generally? I liked one respondent’s answer about using find, heir, and the files themselves to learn about groups being used in a running system, paying attention to the owner, Audi, etc along the way and this is how I do it now, but this approach doesn’t account for the history and evolution. Thanks! Willu Sent from my iPhone

3 years, 9 months

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

1996

1995

1994

1993

1992

1991

1990

TUHS