From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756303AbZBIXuv (ORCPT ); Mon, 9 Feb 2009 18:50:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753250AbZBIXuk (ORCPT ); Mon, 9 Feb 2009 18:50:40 -0500 Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120]:35474 "EHLO cdptpa-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752774AbZBIXui (ORCPT ); Mon, 9 Feb 2009 18:50:38 -0500 Message-ID: <4990C14B.7060802@intertwingly.net> Date: Mon, 09 Feb 2009 18:50:35 -0500 From: Sam Ruby User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Len Brown CC: Thomas Gleixner , Andrew Morton , LKML , linux-acpi@vger.kernel.org, x86@kernel.org, "Maciej W. Rozycki" Subject: Re: [APIC] Kernel panic, rsync corruption, intel q8200, 2.6.28-rc8 References: <4978767D.4060700@intertwingly.net> <20090130000758.1dff0113.akpm@linux-foundation.org> <498885CC.4060509@intertwingly.net> <20090203114849.b661f1ce.akpm@linux-foundation.org> <49890B46.8020308@intertwingly.net> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Len Brown wrote: >>> Do you have a second computer around with a serial port ? If yes, then >>> please add the following to the kernel command line: >>> >>> earlyprintk=serial,ttyS0,115200 apic=debug >>> >>> and connect the serial ports with a null modem cable. Fire up a >>> terminal program on the second machine and capture the output. >> I do have a second computer, and went out and bought a null modem adapter for >> my serial cable and connected the two machines. I've tried installing minicom >> and also connecting it to ttyS0 at 115200 baud on the second machine, but when >> I boot the first machine I don't see any output on the terminal. > > /boot/grub/menu.lst: > > serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 > terminal --timeout=300 serial console > > is what I use. > > this will give you a prompt from grub even before the kernel boots > so you can select (and edit) your kernel via menu over the serial line > if you wish. I've got that working now. I used minicom on the remote machine, capturing the output. You can see me fumbling around, editing the kernel command and booting here: http://intertwingly.net/stories/2009/02/09/minicom.out While it is difficult to make out what I did given line wrapping, etc, what I started with was: /boot/vmlinuz-2.6.27-11-generic root=UUID=4fce230e-fe72-4685-aab0-294ef1c20efa ro noapic quiet splash After editing, what I had was /boot/vmlinuz-2.6.27-11-generic root=UUID=4fce230e-fe72-4685-aab0-294ef1c20efa ro quiet splash earlyprintk=serial,ttyS0,115200 apic=debug As you can see, the last line I saw was "Starting up ...", after which point the "MP-BIOS bug: 8254 timer not connected to IO-APIC" etc output appeared on the monitor that is directly connected to the machine being booted (i.e., this text did not appear on the minicom session). > If this doesn't work, then the kernel earlyprintk is unlikely to work > also. At the moment, it looks like it works, but earlyprintk does not work for me, at least not on Ubuntu 8.10, kernel 2.6.27-11-generic. > Note that there may be some BIOS SETUP options related to the serial port > -- worth checking. > > Also, in minicom, be sure to turn off HW flow control > > there is a fancy serial console document someplace on this, > probably at http://tldp.org/ As I have managed to get grub to talk to the serial console, I did not explore these options further. Please let me know if there is something in particular I should explore. > good luck, > -Len - Sam Ruby