From owner-freebsd-current@FreeBSD.ORG Tue Feb 7 04:21:00 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 90E8216A420; Tue, 7 Feb 2006 04:21:00 +0000 (GMT) (envelope-from Cy.Schubert@komquats.com) Received: from spqr.komquats.com (S0106002078125c0c.gv.shawcable.net [24.108.150.239]) by mx1.FreeBSD.org (Postfix) with ESMTP id 20A7E43D46; Tue, 7 Feb 2006 04:20:58 +0000 (GMT) (envelope-from Cy.Schubert@komquats.com) Received: from cwsys.cwsent.com (cwsys [10.1.1.1]) by spqr.komquats.com (Postfix) with ESMTP id 9C1884C5C5; Mon, 6 Feb 2006 20:20:57 -0800 (PST) Received: from cwsys (localhost [127.0.0.1]) by cwsys.cwsent.com (8.13.4/8.13.4) with ESMTP id k174L4uZ001872; Mon, 6 Feb 2006 20:21:04 -0800 (PST) (envelope-from Cy.Schubert@komquats.com) Message-Id: <200602070421.k174L4uZ001872@cwsys.cwsent.com> X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.0.4 From: Cy Schubert X-os: FreeBSD X-Sender: cy@cwsent.com X-URL: http://www.komquats.com/ To: freebsd-current@freebsd.org, netchild@freebsd.org In-Reply-To: Message from Cy Schubert of "Sun, 29 Jan 2006 14:52:10 PST." <200601292252.k0TMqAGJ031333@cwsys.cwsent.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 06 Feb 2006 20:21:04 -0800 Sender: Cy.Schubert@komquats.com Cc: Subject: Re: 7.0-CURRENT Hang X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Cy Schubert List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Feb 2006 04:21:00 -0000 I identified the problem (see my original discussion about this in attached the email below). On the Pentium P54C model (that's an old 120 MHz Pentium I use as a 4.x, 5.x, and 7.x ports build testbed) the CPUID instruction when called with AL = 0, CPUID returns EAX = EBX = ECX = EDX = 0. The code fragment in identcpu.c below results in "rounds" becoming 0xffffffff. do_cpuid(0x2, regs); rounds = (regs[0] & 0xff) - 1; The subsequent loop of the following will loop virtually for ever (it takes forever tor this machine to count down from 0xffffffff performing a very great many calls to get_INTEL_TLB in the process, virtually hanging the machine in the process. while (rounds > 0) { [... code ...] rounds--; } To resolve my problem I cobbled up the following patch to identcpu.c: --- sys/i386/i386/identcpu.c.orig Thu Feb 2 04:44:09 2006 +++ sys/i386/i386/identcpu.c Mon Feb 6 18:47:16 2006 @@ -1237,7 +1237,7 @@ do_cpuid(0x2, regs); - rounds = (regs[0] & 0xff) - 1; + rounds = (regs[0] & 0xff); for (regnum = 0; regnum <= 3; ++regnum) { if ((regs[regnum] & (1<<31)) == 0) { @@ -1249,7 +1249,7 @@ } } - while (rounds > 0) { + while (rounds > 1) { do_cpuid(0x2, regs); for (regnum = 0; regnum <= 3; ++regnum) { @@ -1452,7 +1452,7 @@ u_int nwaycode; do_cpuid(0x2, regs); - rounds = (regs[0] & 0xff) - 1; + rounds = (regs[0] & 0xff); for (regnum = 0; regnum <= 3; ++regnum) { if ((regs[regnum] & (1<<31)) == 0) { @@ -1468,7 +1468,7 @@ } } - while (rounds > 0) { + while (rounds > 1) { do_cpuid(0x2, regs); for (regnum = 0; regnum <= 3; ++regnum) { It fixes the hang. Cheers, Cy Schubert Web: http://www.komquats.com and http://www.bcbodybuilder.com FreeBSD UNIX: Web: http://www.FreeBSD.org BC Government: "Lift long enough and I believe arrogance is replaced by humility and fear by courage and selfishness by generosity and rudeness by compassion and caring." -- Dave Draper In message <200601292252.k0TMqAGJ031333@cwsys.cwsent.com>, Cy Schubert writes: > I'm experiencing the following hang on my -CURRENT testbed (which also > serves as a 4.11, 5.4, and 6.0 testbed). Only under 7.0-CURRENT does it > hang during boot using a stock out of the box GENERIC kernel. The machine > is an old P120. Any ideas? > > OK include /boot/cwtest/foobar > | > > cwtest.foobar loader file selected > unload complete > currdev set to disk2s1a: > /boot/kernel/kernel text=0x4e15c4 data=0x84900+0xa026c > syms=[0x4+0x67ea0+0x4+0x7f4ff] > new kernel has been loaded > > OK boot -s > GDB: no debug ports present > KDB: debugger backends: ddb > KDB: current backend: ddb > Copyright (c) 1992-2006 The FreeBSD Project. > Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 > The Regents of the University of California. All rights reserved. > FreeBSD 7.0-CURRENT #0: Fri Jan 27 13:49:18 PST 2006 > root@cwsys:/export/obj/opt/src/cvs-current/src/sys/GENERIC > WARNING: WITNESS option enabled, expect reduced performance. > > At this point I need to reset the machine. > > > > Cheers, > Cy Schubert > Web: http://www.komquats.com and http://www.bcbodybuilder.com > FreeBSD UNIX: Web: http://www.FreeBSD.org > BC Government: > > "Lift long enough and I believe arrogance is replaced by > humility and fear by courage and selfishness by generosity > and rudeness by compassion and caring." > -- Dave Draper > > > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >