Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 30 Jul 2001 19:00:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 30 Jul 2001 19:00:17 -0400 Received: from atlrel2.hp.com ([156.153.255.202]:24546 "HELO atlrel2.hp.com") by vger.kernel.org with SMTP id ; Mon, 30 Jul 2001 19:00:04 -0400 Message-ID: <3B65E711.A3828E15@fc.hp.com> Date: Mon, 30 Jul 2001 17:00:33 -0600 From: Khalid Aziz X-Mailer: Mozilla 4.78 [en] (X11; U; Linux 2.4.5 i686) X-Accept-Language: en MIME-Version: 1.0 To: Andreas Dilger Cc: Linux kernel development list Subject: Re: Support for serial console on legacy free machines In-Reply-To: <200107302240.f6UMeWg2001230@webber.adilger.int> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing Andreas Dilger wrote: > > What bothers me is that new systems don't have a serial port, and no ISA > slots, so there is no hope of getting a "serial console" support without > ACPI (which is rather heavyweight AFAIK). USB is far too complex to use > for early-boot debugging, so what else is left? I am puzzled. How would you get "serial console" support even with ACPI unless there IS a serial port on the system????? All ACPI can do is tell you where the serial port is. > > There was some talk about using a low level IP console over ethernet, > but I would imagine this is more complex than the same thing on a > parallel-port. I could be wrong. Of course, an IP console has the > advantage of being useful over a longer distance than a parallel cable, > but may have the disadvantage of poor security. > IP console qould require a significant amount of network protocol stack to be up and running. That would make console available pretty late in bootup sequence. IMO, console should be simple and reliable if it is to be used for debugging at all. Even if console were to be used to print just errors and information messages, it should still be pretty simple to ensure those messages do get printed out. A serial port meets those requirements. USB is too complex, as you said, unless it could be managed fully in firmware/BIOS. But then again I would hate to have kernel make calls into firmware for simple console I/O. -- Khalid ==================================================================== Khalid Aziz Linux Systems Operation R&D (970)898-9214 Hewlett-Packard khalid@fc.hp.com Fort Collins, CO - 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/