From owner-freebsd-hackers@FreeBSD.ORG Sun Oct 3 18:20:07 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id AE64E16A4CE for ; Sun, 3 Oct 2004 18:20:07 +0000 (GMT) Received: from cruzio.com (dsl3-63-249-85-132.cruzio.com [63.249.85.132]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7825743D3F for ; Sun, 3 Oct 2004 18:20:07 +0000 (GMT) (envelope-from brucem@mail.cruzio.com) Received: from mail.cruzio.com (localhost [127.0.0.1]) by cruzio.com (8.12.10/8.12.10) with ESMTP id i93ILEC1000361; Sun, 3 Oct 2004 11:21:14 -0700 (PDT) (envelope-from brucem@mail.cruzio.com) Received: (from brucem@localhost) by mail.cruzio.com (8.12.10/8.12.10/Submit) id i93ILEro000360; Sun, 3 Oct 2004 11:21:14 -0700 (PDT) (envelope-from brucem) Date: Sun, 3 Oct 2004 11:21:14 -0700 (PDT) From: "Bruce R. Montague" Message-Id: <200410031821.i93ILEro000360@mail.cruzio.com> To: andrea@webcom.it cc: freebsd-hackers@freebsd.org cc: durham@jcdurham.com Subject: Re: Sudden Reboots X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Oct 2004 18:20:07 -0000 Hi, Andrea, regarding inverted page tables: > Actually, all Power and PowerPC chips have this... Thanks for pointing that out. I believe the entire line of IBM virtual memory hardware that supports IBM's form of "inverted page tables" is all directly related, if not the same, and descends from the never-completed 1970s-era IBM "Future System" (FS) project. Or perhaps it was a version redone for the System/38 that used lessons learned from the FS? Is this right? The AS/400 has successfully used this architecture for a long time. Most of the other systems that have used this architecture (RT, RS) seem to have never quite caught on. Is this VM unit and the Power/PowerPC's the same? They "cheat" a bit with a hash table to keep the cost of the associative memory down; perhaps increasing its size is the natural evolution of this VM architecture? Are there any "true" single-level store OSes running on this inverted PT hardware? (That is, where RAM is literally treated as just an "invisible" performance cache for a secondary-storage primary memory.) I assume the OS/400 is, but maybe an expert knows for sure? OS/400 runs on modern AS/400's which use the PowerPC, unless I'm mistaken... Sorry to have so many questions and no answers, hopefully the coffee will kick in soon. The FS apparently was IBM's biggest failure; some say it had a lot to do with the growth of silicon valley. A history of the IBM "Future System" and the technologies it spawned would be very interesting. There seems to be little info on it around: www.cs.clemson.edu/~mark/fs.html - bruce