On Mon, Mar 30, 2020 at 3:43 AM Paul Ruizendaal <
pnr@planet.nl> wrote:
To be honest, late 1981 sounds a bit too early for the merge. The 4.1 code was ready in June 1981 and the ’select’ system call was first proposed in July 1981, so it is possible. However, in the BSD line ’select’ was not fully implemented until March/April 1982.
Please be careful here. 4.1BSD is different from the pre-'4.2' released and 4.2BSD itself. 4.1aBSD was the first pseudo release[1] that started to have the major surgery to support Bill's sockets idea and splice in the UCB rewrite of the BBN code. 4.1BSD was the first system for the Vax that really wide distribution. 'Anyone' with an AT&T license could get it and most people did. Remember this is the system that BBN (Gurwitz) did the original IP/TCP support (sans sockets - i.e. /dev/ip /dev/tcp ...). Your date of June '81 for the 4.1BSD release seems late, but I'll accept it. 3BSD was 1979, and I thought 4BSD was a year later, with 4.1BSD a few months after 4BSD (few people actually got 4BSD)
That said, Bill and Sam did the heavy lifting on select(2) first in 4.1aBSD and there were some issues (again I have forgotten the details -- I do remember, I was working on my thesis and I had a do a huge rewrite of the AP kernel support to handle select(2) properly). I remember talking to Sam (arguing with him most probably) about it one night before it was fully created. I want to say, he had worked on something similar at the firm he was at (the firm name I now forget -- si-mumble -- they were in Mt. View) before he joined CRSG. I don't remember now the issues I had, but I do remember it was a bit of mess to support the way the AP hardware assumed it could do DMA on the UBA[2]
[1] 4.1a/4.1b/4.1cBSD was officially internal to UCB and some ARPA-sites, although I would have expected someone like Dennis in 1127 to have been sent it also, as wnj was in the process of leaving for Sun and he took them with him. For instance, I would take 4.1c to Masscomp. The key is that these were not as widely distributed as 4.1BSD. 4.2BSD would really accelerate BSD UNIX uptake, because of the networking support but there was more than 2-3 years between 4.1BSD and 4.2BSD.
[2] The AP's MMU/DMA interface at the time, was causing me great hair, and that was likely to have been part of the reason I wanted some help/changes in the KPI interface - which is actually funny, they eventually came with the CMU Mach MMU changes of 4.4BSD (which was much more friendly to a multiprocessor/coprocessor architecture). FWIW: I never got them when I was at UCB.