The Unix Heritage Society mailing list
 help / color / mirror / Atom feed
From: Dan Halbert <halbert@halwitz.org>
To: tuhs@minnie.tuhs.org
Subject: Re: [TUHS] mmap origin (was Systematic approach to command-line interfaces)
Date: Thu, 30 Sep 2021 08:56:28 -0400	[thread overview]
Message-ID: <3078f9ad-0c1b-52b7-4d76-973ff3fde7f4@halwitz.org> (raw)
In-Reply-To: <EDEDF06A-C3A2-4E17-8F78-14DF63C8C5AD@planet.nl>

On 9/30/21 5:01 AM, Paul Ruizendaal via TUHS wrote:
> 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.
>
3BSD and I think 4.1BSD had vread() and vwrite(), which looked like 
regular read() and write() but accessed pages only on demand. I was a 
grad student at Berkeley at the time and remember their genesis. Bill 
and I were eating lunch from Top Dog on the Etcheverry Hall plaza, and 
were talking about memory-mapped I/O. I remember suggesting the actual 
names, perhaps as a parallel to vfork(). I had used both TENEX and 
Multics, which both had page mapping. Multics' memory-mapped segments 
were quite fundamental, of course. I think we were looking for something 
vaguely upward compatible from the existing system calls. We did not 
leap to an mmap() right away just because it would have been a more 
radical shift than continuing the stream orientation of UNIX. I did not 
implement any of this: it was just a brainstorming session.

Dan H

  parent reply	other threads:[~2021-09-30 13:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-30  9:01 Paul Ruizendaal via TUHS
2021-09-30 10:39 ` [TUHS] Early shared library implementations arnold
2021-09-30 14:12   ` Charles H Sauer
2021-10-11  6:43   ` Rob Gingell via TUHS
2021-10-11  7:08     ` George Michaelson
2021-10-11 14:22       ` Clem Cole
2021-10-17 22:19     ` Chris Hanson
2021-10-17 22:15   ` Chris Hanson
2021-09-30 12:56 ` Dan Halbert [this message]
2021-10-01 11:36 [TUHS] mmap origin (was Systematic approach to command-line interfaces) Paul Ruizendaal

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=3078f9ad-0c1b-52b7-4d76-973ff3fde7f4@halwitz.org \
    --to=halbert@halwitz.org \
    --cc=tuhs@minnie.tuhs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).