Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262037AbTHTQO6 (ORCPT ); Wed, 20 Aug 2003 12:14:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262043AbTHTQO5 (ORCPT ); Wed, 20 Aug 2003 12:14:57 -0400 Received: from mail.kroah.org ([65.200.24.183]:11964 "EHLO perch.kroah.org") by vger.kernel.org with ESMTP id S262037AbTHTQO4 (ORCPT ); Wed, 20 Aug 2003 12:14:56 -0400 Date: Wed, 20 Aug 2003 09:14:39 -0700 From: Greg KH To: Thomas Molina Cc: Linux Kernel Mailing List , Zwane Mwaikambo Subject: Re: Console on USB Message-ID: <20030820161439.GD1354@kroah.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2769 Lines: 62 On Tue, Aug 19, 2003 at 10:20:51PM -0500, Thomas Molina wrote: > I have just spent a very frustrating evening trying to get console on USB > working. My laptop does not have regular DB-9 serial connectors, only > USB. So I ordered a USB to serial converter, Which usb to serial converter? Not all of them work with Linux. Does this device work with Linux _not_ as a serial console device? > configured a 2.6.0-test3 > kernel, added a console=/dev/ttyUSB0 to the kernel command line and > connected this to my desktop with a null modem adapter. However, I am > unable to get output from this setup on the desktop. On another setup I > can get a normal serial console output, so I am fairly confident I can set > things up correctly. Which "serial console" are you trying to get working? The kernel log console, or a login console? > Googling around and doing a search on lkml archives gave some minimal > help, but I can find very little info past early to mid 2.5 kernels. The > configuration doesn't quite seem to work the way I read documentation. > For instance, the web pages I can find indicate I should be able to build > this modular; however the configuration makes the setting of console on > usb depend on USB being y and EXPERIMENTAL being defined. What web page says you can build this modular? You have to build it into the kernel. > In /var/log/messages I can see the USB-to-serial converter being recogized > and the driver being loaded, just before the synaptics touchpad is probed. Can you show us the relevant part of the kernel logs? > It looks like things are correct, but, as I said, I am unable to get > output. Am I headed for frustration, or is there some advice to get good > results? You are headed for frustration. USB serial console was a neat hack, but pretty pointless. It has the following problems: - can't see oopses before USB starts up, and USB starts up almost last in the system boot process. - really can not capture oopses very well as USB is interrupt driven - most usb-serial converters have a very small buffer, so you constantly get over-runs in printing out console messages (meaning that only a few of the devices will even work properly, you usually have to buy one of the expensive ones to see all messages.) > Is there any advice I might be able to use to get this going? I really > want to be able to catch some oops output. Buy a machine with a serial port. That's my recommendation :) Good luck, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/