Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756442AbZCEWkh (ORCPT ); Thu, 5 Mar 2009 17:40:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753566AbZCEWk2 (ORCPT ); Thu, 5 Mar 2009 17:40:28 -0500 Received: from fifo99.com ([67.223.236.141]:60051 "EHLO fifo99.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753162AbZCEWk2 (ORCPT ); Thu, 5 Mar 2009 17:40:28 -0500 Subject: Re: [tip:x86/doc] x86/doc: mini-howto for using earlyprintk=dbgp From: Daniel Walker To: Yinghai Lu Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, stern@rowland.harvard.edu, randy.dunlap@oracle.com, ebiederm@xmission.com, akpm@linux-foundation.org, gregkh@suse.de, tglx@linutronix.de, sarah.a.sharp@intel.com, mingo@elte.hu, linux-tip-commits@vger.kernel.org In-Reply-To: <49B02692.3000500@kernel.org> References: <49AF18B7.4050305@kernel.org> <1236267366.5937.56.camel@desktop> <49B02692.3000500@kernel.org> Content-Type: text/plain Date: Thu, 05 Mar 2009 14:40:23 -0800 Message-Id: <1236292823.5937.84.camel@desktop> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2882 Lines: 82 On Thu, 2009-03-05 at 11:22 -0800, Yinghai Lu wrote: > > thanks for checking it. > > can you submit patch to Ingo according to tip/master? Hows this? -- Fix up some typos, and make the requirements section slightly cleaner. Signed-Off-By: Daniel Walker dwalker@fifo99.com diff --git a/Documentation/x86/earlyprintk.txt b/Documentation/x86/earlyprintk.txt index 607b1a0..5b51aef 100644 --- a/Documentation/x86/earlyprintk.txt +++ b/Documentation/x86/earlyprintk.txt @@ -9,7 +9,9 @@ and two USB cables, connected like this: 1. There are three specific hardware requirements: - a.) Host/target system needs to have USB debug port capability. + a.) You will need two USB ports. One on the client/console system and one one the target system. + + b.) The client/console and target USB ports must have the debug port capability. You can check this capability by looking at a 'Debug port' bit in the lspci -vvv output: @@ -35,15 +37,13 @@ and two USB cables, connected like this: ( If your system does not list a debug port capability then you probably wont be able to use the USB debug key. ) - b.) You also need a Netchip USB debug cable/key: + c.) You also need a Netchip USB debug cable/key: http://www.plxtech.com/products/NET2000/NET20DC/default.asp This is a small blue plastic connector with two USB connections, it draws power from its USB connections. - c.) Thirdly, you need a second client/console system with a regular USB port. - 2. Software requirements: a.) On the host/target system: @@ -54,7 +54,7 @@ and two USB cables, connected like this: And you need to add the boot command line: "earlyprintk=dbgp". (If you are using Grub, append it to the 'kernel' line in - /etc/grub.conf) + grub.conf (i.e. /boot/grub/grub.conf) ) NOTE: normally earlyprintk console gets turned off once the regular console is alive - use "earlyprintk=dbgp,keep" to keep @@ -72,7 +72,7 @@ and two USB cables, connected like this: Now this channel of kernel messages is ready to be used: start your favorite terminal emulator (minicom, etc.) and set - it up to use /dev/ttyUSB0 - or use a raw 'cat /dev/ttyUSBx' to + it up to use /dev/ttyUSBx - or use a raw 'cat /dev/ttyUSBx' to see the raw output. c.) On Nvidia Southbridge based systems: the kernel will try to probe @@ -92,7 +92,7 @@ and two USB cables, connected like this: On the client/console system do: - cat /dev/ttyUSB0 + cat /dev/ttyUSBx And you should see the help line above displayed shortly after you've provoked it on the host system. -- 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/