[TUHS] A few comments on porting the Bourne shell

[Ron Natalie]

Paging was what they were referring to.   The Bell releases at the time 
only swapped like they did on the PDP-11.
BSD allowed only fragments of the program to need be resident.

The joke as “It ain’t virtual unless it isn’t all there."


------ Original Message ------
>From "Dan Cross" <crossd at gmail.com>
To "Warner Losh" <imp at bsdimp.com>
Cc "Jonathan Gray" <jsg at jsg.id.au>; "Paul Ruizendaal" <pnr at planet.nl>; 
"The Eunuchs Hysterical Society" <tuhs at tuhs.org>; "segaloco" 
<segaloco at protonmail.com>
Date 1/1/2023 12:35:12 AM
Subject [TUHS] Re: A few comments on porting the Bourne shell

>On Sun, Jan 1, 2023 at 12:27 AM Warner Losh <imp at bsdimp.com> wrote:
>>  On Sat, Dec 31, 2022, 9:38 PM Jonathan Gray <jsg at jsg.id.au> wrote:
>>>  [snip]
>>>  Bourne's AsiaBSDCon 2016 talk also lists 1976
>>>  and goes on to discuss sbrk() use causing problems with ports
>>>https://youtu.be/7tQ2ftt3LO8?t=715
>>
>>  And at 5:18 he says he had a vax lab with three vaxen and the Lab's vax port didn't have virtual memory. Bill Joy with 3BSD which had virtual memory. They installed it on the vaxen because they were hitting physical memory limits for some of their programs....
>
>One wonders what is meant by "virtual memory" in this context. I
>contend that Unix has had "virtual memory" since moving off of the
>PDP-11/20, in the sense of having a virtual address space that was
>mapped onto a (possibly contiguous) physical address space. I think
>all of these references mean demand paging, possibly with page
>reclamation or whole-process swapping under memory pressure.
>
>         - Dan C.