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
next prev 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
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