From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, NICE_REPLY_A autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 32376 invoked from network); 30 Sep 2021 13:02:22 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 30 Sep 2021 13:02:22 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id A88E39CB03; Thu, 30 Sep 2021 23:02:18 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 1899A9CAE6; Thu, 30 Sep 2021 23:01:48 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 785FE9CAE4; Thu, 30 Sep 2021 23:01:45 +1000 (AEST) X-Greylist: delayed 315 seconds by postgrey-1.36 at minnie.tuhs.org; Thu, 30 Sep 2021 23:01:44 AEST Received: from smtp81.iad3a.emailsrvr.com (smtp81.iad3a.emailsrvr.com [173.203.187.81]) by minnie.tuhs.org (Postfix) with ESMTPS id BB6CB9CAE3 for ; Thu, 30 Sep 2021 23:01:44 +1000 (AEST) X-Auth-ID: halbert@halwitz.org Received: by smtp35.relay.iad3a.emailsrvr.com (Authenticated sender: halbert-AT-halwitz.org) with ESMTPSA id C871B5975 for ; Thu, 30 Sep 2021 08:56:28 -0400 (EDT) To: tuhs@minnie.tuhs.org References: From: Dan Halbert Message-ID: <3078f9ad-0c1b-52b7-4d76-973ff3fde7f4@halwitz.org> Date: Thu, 30 Sep 2021 08:56:28 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Classification-ID: ce84732c-1326-4356-b78e-fd331f6a73d1-1-1 Subject: Re: [TUHS] mmap origin (was Systematic approach to command-line interfaces) X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" 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