The presence of some sort of shared memory facility in the BBN V6 Unix kernel got me thinking about the origins of shared memory on Unix. I had a vague recollection that primordial versions were present in either PWB or CB3, but a quick glance at the source indicates that this is not correct. What are the origins of shared memory on Unix, i.e. what came before mmap() and SysV IPC? Was the BBN kernel the first to implement such a facility on Unix? Paul

I*'m not sure what you mean by CB3, but these features (shared memory, semaphores, IPC) were added to CB-UNIX (Bell Labs, Columbus) precisely because they were needed in real time telco systems and not preset in the versions from New Jersey. This would have been in the early 1980s. When I got there in 1981 I think CB-UNIX was already well established and had these features. (These would show up, ironically, in /usr/ucb, which did not stand for Berkeley.)

Wasn't shmget() and friends added vor SysV past 1982?

On Wed, Feb 1, 2017 at 12:24 PM, Joerg Schilling &lt;schily(a)schily.net&gt; wrote: ​AT&T Unix naming get's weird as they hire marketing people that don't quite get it. V6 -> PWB [1.0 ~77] ---| | | + UNIX/TS[~79] -- +​ PWB 2.0 [~79] ----- PWB 3.0[~80] <-- internal name of release The "UNIX Support Group" - aka Summit - is supposed to be creating UNIX flavors for the different labs and operating companies and Research is to go back to doing research. Thus PWB 3.0 is supposed to start to be a "superset" of the features added by the different labs, Columbus, IH, *etc*... But it took a few spins before all the different hacks, additions were agreed too and added. There was much fighting inside of BTL as we see outside. IIRC an unreleased version of PWB 4.0 had the Columbus features in it as Horton points out. Note that AT&T Marketing renames PWB 3.0 -- System III thinking that "Programmer's Workbench" would be a bad name to sell against IBM, and this it the first non-research system for License outside of the the labs. If you look at the documentation set, et al - it all says PWB 3.0 on the cover and throughout Also, the BSD vs AT&T wars basically start around this time.... Roll the clock forward and here is an new problem the PWB 4.0 moniker was used internally, but AT&T marketing want to get rid of the PWB term - so the decree comes down the next release is to be called System V. Certainly by this point, the Columbus changes had been folded into the main line kernel in Summit by then. But as I said, my memory is what made it into SystemV and what was in CB-UNIX were similar but a little different. Clem

Clem Cole &lt;clemc(a)ccc.com&gt; wrote: wrote: BTW: Is this: /*---------------------------------------------------------- ----------------*/ PY-77-05(PWB PIB) 2/22/77 PY-77-05(PWB PIB) TO: All BISP Programmer's Workbench (PWB) Users SUBJECT: Release 4.0 of SCCS/PWB /*---------------------------------------------------------- ----------------*/ Release 4.0 of SCCS or release 4.0 of PWB?

I'm almost sure that SCCS/PWB refers to SCCS, not to the OS. By the time of this memo (1977) I was long-gone from SCCS, and was working under Rudd on a new system to produce telephone directories.

I can't speak for the dates, but Ken did a hack to the OS to interface with his Chess machine. Recall that all the I/O on the PDP-11 was memory mapped, so as I recall he simply mapped a piece of kernel memory into user space. Was never privvy to the details. I do remember a conversation with Dennis about semaphores, though. He mentioned that no less than five groups inside of Bell Labs had hacked semaphores into the kernel. Each group did it differently. He thought they were all a bad idea -- his argument was, "what do you do if a process sets a semaphore and then dies? It's pretty clear that either releasing the semaphore or leaving it set would be catastrophic in some cases." (Of course there were other similar problems, such as a process closing its files and dying, and then the kernel discovering that the disc was full. Luckily, these days, the disc rarely gets full...) Also, a comment from my own experience with AT&T marketing. When I was responsible for the System V languages in Summit, I was told that a marketing group was staffed and that there was a person in charge of marketing the language products (at the time, C, Cfront (becoming C++), Fortran, Pascal, and Ada). I set up a monthly meeting with this person. The meetings went on for over a year, but *I never met with the same person twice!* It seemed that the only thing the marketing group knew how to do was reorganize the marketing group... At the time, a lot of people buying VAXes were running VMS because its FORTRAN was far better than UNIX F77 -- in particular, it had an optimizer. I started a project to build an optimizer for FORTRAN, and staffed it with several very good people. Every six weeks there would be an attempt to kill the project. Each time I'd repeat the argument for doing it, and it would be saved. We almost started to put these attempts to kill it on the calendar. At no time did I get any feedback, positive or negative, from AT&T marketing. When I left AT&T in early 1986, the optimizer, by now almost complete, was immediately killed again. I was later told by one of my former team members that it was revived several months later and finally made it out. And that the next year it was the best-selling add-on to System V. Steve ----- Original Message ----- From: arnold(a)skeeve.com To: &lt;schily(a)schily.net&gt;et>, &lt;clemc(a)ccc.com&gt; Cc: &lt;tuhs(a)minnie.tuhs.org&gt; Sent: Wed, 01 Feb 2017 11:33:05 -0700 Subject: Re: [TUHS] shared memory on Unix Clem Cole &lt;clemc(a)ccc.com&gt; wrote: this cover Sort of. I did some contract work for Southern Bell circa 1983. They were still part of the Bell System then. I worked on a PDP-11 running Unix 4.0. At the time, the policy was to release externally one version behind what was being run internally, so System III was released to the world while the Bell System was using Unix 4.0. I still have the manual; I'm pretty sure "PWB" and "Programmer's Workbench" are not on the cover, it was just called "UNIX". As UNIX 5.0 was approaching, someone decided that to be one release behind on the outside was dumb, thus the jump from System III to System V. The doc I have describes UNIX as an operating system for the PDP-11, the VAX 11/780 *and* the IBM S/370 series of systems and the source code directory had the machine dependent bits for the IBM. Too bad that stuff never made it out. It's too bad that all I have is just the paper, but that's all I could get. That was a fun job, I learned a lot. Over lunch every day I read a few more pages of the manual, basically reading it from cover to cover by the time I was done. What a great way to learn the system! Arnold

The so-called Columbus shared memory feature was in their system in the mid-1970s, along with a few other things such as semaphores and inter-process messages. I seem to recall the acronym MAUG, but I may have a letter or two wrong. Something like Multi Access User ____. The much later System V features had a completely different API. Hey, Doug, do you remember this? In the early 1970s, there were a couple of UNIX meetings at Murray Hill, at which various Bell Labs groups presented on what they were doing with UNIX, and a group, perhaps Columbus, said that UNIX wasn't capable of doing what they wanted, so they had modified it. You asked the question, "Why are you using UNIX?" To my knowledge, having witnessed another decade or so of groups trying to bend UNIX to their will, it was the last time the question was asked. --Marc > > I*'m not sure what you mean by CB3, but these features (shared memory, > > semaphores, IPC) were added to CB-UNIX (Bell Labs, Columbus) precisely > > because they were needed in real time telco systems and not preset in > > the versions from New Jersey. This would have been in the early 1980s. > > When I got there in 1981 I think CB-UNIX was already well established > > and had these features. (These would show up, ironically, in /usr/ucb, > > which did not stand for Berkeley.)

In any case, the man page for maus is from November 1979, so it goes back at least as far as that. When was CB Unix 1.0 put together?