From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266328AbUANXR0 (ORCPT ); Wed, 14 Jan 2004 18:17:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266337AbUANXQz (ORCPT ); Wed, 14 Jan 2004 18:16:55 -0500 Received: from gateway-1237.mvista.com ([12.44.186.158]:48622 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S266328AbUANXQd (ORCPT ); Wed, 14 Jan 2004 18:16:33 -0500 Message-ID: <4005C361.8050006@mvista.com> Date: Wed, 14 Jan 2004 14:32:01 -0800 From: George Anzinger Organization: MontaVista Software User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2) Gecko/20021202 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Amit S. Kale" CC: Andrew Morton , jim.houston@comcast.net, discuss@x86-64.org, ak@suse.de, shivaram.upadhyayula@wipro.com, lkml , Pavel Machek Subject: Re: [discuss] Re: kgdb for x86_64 2.6 kernels References: <000e01c3d476$2ebe03a0$4008720a@shivram.wipro.com> <200401122020.08578.amitkale@emsyssoft.com> <40046296.1050702@mvista.com> <200401141854.23423.amitkale@emsyssoft.com> In-Reply-To: <200401141854.23423.amitkale@emsyssoft.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Amit S. Kale wrote: > On Wednesday 14 Jan 2004 2:56 am, George Anzinger wrote: > >>Amit S. Kale wrote: >> >>>8250.patch changes generic 8250/16550 driver behavior only in following >>>ways 1. It adds a function serial8250_release_irq to release those serial >>>ports which share an irq with kgdb irq. >>>2. There are checks so that a serial port that uses an irq used by an >>>initialized kgdb can't be initialized or started. >>> >>>File kgdb_8250.c is independent of 8250.c kgdb_8250.c depends on >>>KGDB_8250 and 8250.c depends on SERIAL_8250 which can be independently >>>configured. kgdb_8250.c can be compiled even if 8250.c is not included. >>>kgdb_8250.c does only the _minimum_ set of initializations required by >>>hardware. >> >>Ok. >> >> >>>Serial interface should be configurable independent of kgdb and may not >>>be configured if ethernet interface is configured. Serial interface is >>>far simpler hence superior for debugging purposes. If it's available, >>>using ethernet interface is out of question. Ethernet interface can be >>>used when serial hardware isn't present or is being used for some other >>>purposes. >> >>I rather think that the serial inteface should be the fall back unless the >>user has told us at configure time that it is not available. I am not >>prepared to make a statment that it is better than eth. The eth intface >>should be much faster, but it has its fingers into a large part of the >>kernel that MAY be the subject of the current session. Thus, I think that >>eth may be better, IF one is clearly not involved in debugging those areas >>of the kernel. (Which, by the way, we need to enumerate at some point.) > > > Ethernet interface spans a large part of the kernel, so is going to be limited > in near future. When it becomes as minimal as the serial interface, both may > be given equal priority. > > At 115kbps, serial interface is usable even when doing a thread list of 200 > threads. Only 200? :) Yes, I agree, but the thing I see about the eth interface is that it allows much more remote debugging, like accrost the country, and it is every so much easier to set up. I don't know about you, but my experience with rs232, which after all, can only be wired one of two ways, it that the probability of getting it wrong is about 90%. -g -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml