From owner-freebsd-current@FreeBSD.ORG Fri Feb 10 23:10:19 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 1C3C516A420; Fri, 10 Feb 2006 23:10:19 +0000 (GMT) (envelope-from keramida@ceid.upatras.gr) Received: from igloo.linux.gr (igloo.linux.gr [62.1.205.36]) by mx1.FreeBSD.org (Postfix) with ESMTP id 312A943D49; Fri, 10 Feb 2006 23:10:17 +0000 (GMT) (envelope-from keramida@ceid.upatras.gr) Received: from flame.pc (aris.bedc.ondsl.gr [62.103.39.226]) (authenticated bits=128) by igloo.linux.gr (8.13.5/8.13.5/Debian-3) with ESMTP id k1AN9uRl013680 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Sat, 11 Feb 2006 01:09:59 +0200 Received: from flame.pc (flame [127.0.0.1]) by flame.pc (8.13.4/8.13.4) with ESMTP id k1AN9ovg001039; Sat, 11 Feb 2006 01:09:50 +0200 (EET) (envelope-from keramida@ceid.upatras.gr) Received: (from keramida@localhost) by flame.pc (8.13.4/8.13.4/Submit) id k1AN9oo7001038; Sat, 11 Feb 2006 01:09:50 +0200 (EET) (envelope-from keramida@ceid.upatras.gr) Date: Sat, 11 Feb 2006 01:09:50 +0200 From: Giorgos Keramidas To: Robert Watson Message-ID: <20060210230950.GA938@flame.pc> References: <20060201235556.GA708@troutmask.apl.washington.edu> <20060207104411.GA1067@flame.pc> <20060207132335.W37594@fledge.watson.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060207132335.W37594@fledge.watson.org> X-Hellug-MailScanner: Found to be clean X-Hellug-MailScanner-SpamCheck: not spam, SpamAssassin (score=-3.351, required 5, autolearn=not spam, ALL_TRUSTED -1.80, AWL 0.85, BAYES_00 -2.60, DNS_FROM_RFC_ABUSE 0.20) X-Hellug-MailScanner-From: keramida@ceid.upatras.gr Cc: freebsd-current@FreeBSD.org, Olivier Houchard , Steve Kargl , freebsd-amd64@FreeBSD.org Subject: Re: HEADSUP: New pts code triggers panics on amd64 systems. X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 10 Feb 2006 23:10:19 -0000 On 2006-02-07 13:26, Robert Watson wrote: >On Tue, 7 Feb 2006, Giorgos Keramidas wrote: >>On 2006-02-01 15:55, Steve Kargl wrote: >>>After a binary search, I have determined that the new pts code is >>>triggering kernel panics on an AMD64 system. >> >> It also makes syscons unusable here. >> >> I just rebuilt a HEAD snapshot from today's latest CVSup, installed it >> in /dev/ad0s1a (my test partition), and the behavior is still the same >> as a few days ago: >> >> - single user mode shell works fine >> >> - in multiuser mode, when syscons reaches a login prompt >> i have to press RET twice to see the last line >> >> It seems that something is broken in the way syscons detects whether an >> output line should be flushed out, but I'm not sure. >> >> A snapshot from -D '2006/01/26 01:30:00 UTC' works fine (just before the >> first pts change). >> >> I don't know how to debug this or provide more useful feedback, but I'll >> look at the diffs later today, when I'm done with $REALJOB stuff. > > Does the instability occur if kern.pts.enable=0, or only when > kern.pts.enable=1? If 0, if you back out the user space changes but leave > tty_pts.c compiled into the kernel, do the instability issues persist? How > about with the kernel code compiled out, but the user space code in place? > > Basically, it would be good to know if what you're seeing is a property of > the pts code being in the kernel at all, or a property of it actually in > use. I'm not sure if what I see is a pts side-effect. I rebuilt a snapshot of HEAD again today, and discovered something else that may help us track this down. A few more observations, in case they prove helpful to someone more acquainted with the way syscons output is supposed to work: - If I keep hitting Scroll-Lock again and again, then syscons output *does* eventually appear. - If I type stuff without seeing it and then press RETURN twice, the previous from last line *does* appear in my terminal. - When pressing CTRL-ALT-ESC, the debugger starts normally, but after typing many times commands that have large output, i.e.: show witness the console locks up entirely. This looks like a locking problem, instead of a pts/syscons one :-/