From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=0.9 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,T_SCC_BODY_TEXT_LINE,URIBL_BLACK autolearn=no autolearn_force=no version=3.4.4 Received: from minnie.tuhs.org (minnie.tuhs.org [50.116.15.146]) by inbox.vuxu.org (Postfix) with ESMTP id AA25B2417E for ; Wed, 19 Jun 2024 18:56:04 +0200 (CEST) Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 038B443A26; Thu, 20 Jun 2024 02:56:00 +1000 (AEST) Received: from mail.ultimate.com (mail.ultimate.com [IPv6:2607:fc50:0:15::100]) by minnie.tuhs.org (Postfix) with ESMTPS id 1904943A24 for ; Thu, 20 Jun 2024 02:55:55 +1000 (AEST) Received: from ultimate.com (localhost [127.0.0.1]) by mail.ultimate.com (8.18.1/8.18.1) with ESMTPS id 45JGtYph008728 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Wed, 19 Jun 2024 12:55:35 -0400 (EDT) (envelope-from phil@ultimate.com) Received: (from phil@localhost) by ultimate.com (8.18.1/8.18.1/Submit) id 45JGtYjI008727; Wed, 19 Jun 2024 12:55:34 -0400 (EDT) (envelope-from phil) From: Phil Budne Message-Id: <202406191655.45JGtYjI008727@ultimate.com> Date: Wed, 19 Jun 2024 12:55:34 -0400 To: tuhs@tuhs.org References: <20240619161720.B301E18C088@mercury.lcs.mit.edu> In-Reply-To: <20240619161720.B301E18C088@mercury.lcs.mit.edu> User-Agent: Heirloom mailx 12.4 7/29/08 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID-Hash: BWZQXT5GVGPMDFYYPEKXY6XP5E745YCF X-Message-ID-Hash: BWZQXT5GVGPMDFYYPEKXY6XP5E745YCF X-MailFrom: phil@ultimate.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: jnc@mercury.lcs.mit.edu X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: [COFF] Re: Supervisor mode on ye olde PDP-11 List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: JNC wrote: > Is there a document for 2.11 which explains in detail why they did that? I > suspect it's actually a little more complicated than just "more address > space". ... > ... Switching overlays took a certain amount of > overhead (since mapping registers had to be re-loaded); if all the networking > code ran in supervisor mode, the supervisor mode mapping registers could be > loaded with the right thing and just left. That's my understanding... It allows mbufs to be mapped only in supervisor mode... https://minnie.tuhs.org/PUPS/Setup/2.11bsd_setup.html says: The networking in 2.11BSD, runs in supervisor mode, separate from the mainstream kernel. There is room without overlaying to hold both a SL/IP and ethernet driver. This is a major win, as it allows the networking to maintain its mbufs in normal data space, among other things. The networking portion of the kernel resides in ``/netnix'', and is loaded after the kernel is running. Since the kernel only looks for the file ``/netnix'', it will not run if it is unable to load ``/netnix'' , sites should build and keep a non-networking kernel in ``/'' at all times, as a backup. NOTE: The ``/unix'' and ``/netnix'' imagines must have been created at the same time, do not attempt to use mismatched images. The ability to have boot tell the kernel which network image to load is on the wish list (had to have something take the place of wishing for disklabels ;-)). https://wfjm.github.io/home/ouxr/ shows the code path for the socket(2) syscall