From: Paul Winalski <paul.winalski@gmail.com>
To: Larry McVoy <lm@mcvoy.com>
Cc: tuhs@tuhs.org, Noel Chiappa <jnc@mercury.lcs.mit.edu>
Subject: Re: [TUHS] Memory management in Dennis Ritchie's C Compiler
Date: Mon, 17 Aug 2020 15:50:29 -0400 [thread overview]
Message-ID: <CABH=_VS=Wyvnb_SoiCfRd3GaYwA47TJhMSRwpryBoEo38T6fyw@mail.gmail.com> (raw)
In-Reply-To: <20200817193050.GC11413@mcvoy.com>
On 8/17/20, Larry McVoy <lm@mcvoy.com> wrote:
> On Mon, Aug 17, 2020 at 03:27:15PM -0400, Noel Chiappa wrote:
[regarding mmap(2)]
>
> Bill Joy imagined it, the prototype is in one the 4.x BSD releases.
> Sun (Joe Moran) actually implemented it first in any Unix variant.
> It's possible the concept existed in some other OS but I'm not aware
> of it.
>
VAX/VMS had the equivalent of mmap(2) back in 1978. You can specify a
range of contiguous pages in virtual memory and associate that with a
(page-aligned) range of blocks in a file. The blocks in the file act
as backing store for the virtual memory. VMS also has a system call
$CRETVA (create virtual address space) that lets you associate a VA
range using the system page file as backing store. The VMS image
activator (runtime loader in Unix-speak) used these primitives to load
program images into virtual memory. More than one process can map the
same region of a file. This is how sharing of read-only program
segments such as .text is implemented.
I think Burroughs OSes had this concept even before VMS.
There is also $EXPREG (expand address region), which is more or less
equivalent to sbrk().
-Paul W.
next prev parent reply other threads:[~2020-08-17 19:51 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 19:27 Noel Chiappa
2020-08-17 19:30 ` Larry McVoy
2020-08-17 19:44 ` Dan Halbert
2020-08-17 19:50 ` Paul Winalski [this message]
2020-08-17 22:05 ` Arthur Krewat
2020-08-18 0:52 ` Rob Gingell
2021-01-29 23:52 ` [TUHS] mmap() (was: Memory management in Dennis Ritchie's C Compiler) Greg A. Woods
-- strict thread matches above, loose matches on Subject: below --
2020-08-27 8:37 [TUHS] Memory management in Dennis Ritchie's C Compiler Paul Ruizendaal
2020-08-26 15:59 Noel Chiappa
2020-08-26 16:09 ` Warner Losh
2020-08-26 19:13 ` Clem Cole
2020-08-26 16:14 ` Jim Geist
2020-08-26 17:31 ` John Cowan
2020-08-26 13:24 Doug McIlroy
2020-08-26 15:41 ` John Cowan
2020-08-25 9:36 Steve Simon
2020-08-17 22:32 Norman Wilson
2020-08-17 22:55 ` Bakul Shah
2020-08-17 23:12 ` Chet Ramey
2020-08-18 6:33 ` arnold
2020-08-17 19:51 Noel Chiappa
2020-08-17 2:02 Noel Chiappa
2020-08-17 18:02 ` Paul Winalski
2020-08-17 18:13 ` Jim Geist
2020-08-17 18:48 ` Paul Winalski
2020-08-17 19:08 ` Jim Geist
2020-08-17 19:28 ` Paul Winalski
2020-08-17 19:35 ` Jim Geist
2020-08-17 19:41 ` Richard Salz
2020-08-17 23:40 ` Steffen Nurpmeso
2020-08-15 21:50 Dibyendu Majumdar
2020-08-16 15:20 ` arnold
2020-08-16 15:27 ` Jim Geist
2020-08-17 16:13 ` Dan Cross
2020-08-17 20:16 ` Dibyendu Majumdar
2020-08-17 20:34 ` Paul Winalski
2020-08-17 20:43 ` Dibyendu Majumdar
2020-08-17 21:05 ` Warner Losh
2020-08-17 22:47 ` Dave Horsfall
2020-08-17 23:06 ` Nemo Nusquam
2020-08-17 21:29 ` Dibyendu Majumdar
2020-08-24 15:58 ` Dan Cross
2020-08-24 17:08 ` John Cowan
2020-08-24 17:15 ` Clem Cole
2020-08-24 17:24 ` Clem Cole
2020-08-24 17:20 ` Dan Cross
2020-08-25 23:06 ` Arthur Krewat
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='CABH=_VS=Wyvnb_SoiCfRd3GaYwA47TJhMSRwpryBoEo38T6fyw@mail.gmail.com' \
--to=paul.winalski@gmail.com \
--cc=jnc@mercury.lcs.mit.edu \
--cc=lm@mcvoy.com \
--cc=tuhs@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).