From owner-freebsd-hackers Sat Jun 15 20:44:59 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id UAA08903 for hackers-outgoing; Sat, 15 Jun 1996 20:44:59 -0700 (PDT) Received: from MindBender.HeadCandy.com (root@[199.238.225.168]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id UAA08775; Sat, 15 Jun 1996 20:44:44 -0700 (PDT) Received: from localhost.HeadCandy.com (michaelv@localhost.HeadCandy.com [127.0.0.1]) by MindBender.HeadCandy.com (8.7.5/8.6.9) with SMTP id UAA14100; Sat, 15 Jun 1996 20:44:25 -0700 (PDT) Message-Id: <199606160344.UAA14100@MindBender.HeadCandy.com> X-Authentication-Warning: MindBender.HeadCandy.com: Host michaelv@localhost.HeadCandy.com [127.0.0.1] didn't use HELO protocol To: port-i386@netbsd.org, hackers@freebsd.org, hardware@freebsd.org Reply-To: michaelv@HeadCandy.com Followup-To: michaelv@HeadCandy.com Subject: write-through bit for 486's with write-back cache Date: Sat, 15 Jun 1996 20:44:18 -0700 From: "Michael L. VanLoon -- HeadCandy.com" Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk I can't find this anywhere on AMD's or Intel's web sites. Their programming docs are pathetically lacking in the web access category. On the AMD "enhanced" 486DX4 and 5x86 chips, they have write-back on-chip cache. However, they mention a bit in CR0 called "PWT" that supposedly makes all cache lines always marked "shared", which effectively makes the cache write-through. Does anyone have a technical reference or programmer's manual for either the AMD 486DX4, 5x86, or Intel 486DX4 chips that specifically details CR0 and this "PWT" bit? I'm assuming the Intel 486DX4 "writeback-enhanced" chips use the same CR0 bit. Hopefully I am assuming correctly. Alternatively, does anyone have a Pentium programmer's manual they could look in to see if they Pentium has this PWT bit in it's CR0 register. Thanks for your help... ----------------------------------------------------------------------------- Michael L. VanLoon michaelv@HeadCandy.com --< Free your mind and your machine -- NetBSD free un*x >-- NetBSD working ports: 386+PC, Mac 68k, Amiga, Atari 68k, HP300, Sun3, Sun4/4c/4m, DEC MIPS, DEC Alpha, PC532, VAX, MVME68k, arm32... NetBSD ports in progress: PICA, others... Roll your own Internet access -- Seattle People's Internet cooperative. If you're in the Seattle area, ask me how. -----------------------------------------------------------------------------