Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757508AbZCEXsw (ORCPT ); Thu, 5 Mar 2009 18:48:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754281AbZCEXsn (ORCPT ); Thu, 5 Mar 2009 18:48:43 -0500 Received: from fifo99.com ([67.223.236.141]:45891 "EHLO fifo99.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753829AbZCEXsm (ORCPT ); Thu, 5 Mar 2009 18:48:42 -0500 Subject: Re: [tip:x86/doc] x86/doc: mini-howto for using earlyprintk=dbgp From: Daniel Walker To: Alan Stern Cc: Yinghai Lu , mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, 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: References: Content-Type: text/plain Date: Thu, 05 Mar 2009 15:48:41 -0800 Message-Id: <1236296921.5937.109.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: 4604 Lines: 120 On Thu, 2009-03-05 at 17:54 -0500, Alan Stern wrote: > On Thu, 5 Mar 2009, Daniel Walker wrote: > > > 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. > > s/one one/one on/ > > You might also try harder to observe the 80-column rule. > > > + > > + 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. > > No. It draws power from one of its USB connections (the one on the > right side when you're looking at the face with the PLX logo). > > Alan Stern -- Fix up some typos, and make the requirements section slightly cleaner. Updated the power draw comment per Alan Stern. Signed-Off-By: Daniel Walker diff --git a/Documentation/x86/earlyprintk.txt b/Documentation/x86/earlyprintk.txt index 607b1a0..ac913a6 100644 --- a/Documentation/x86/earlyprintk.txt +++ b/Documentation/x86/earlyprintk.txt @@ -9,7 +9,11 @@ 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 on + 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: @@ -35,14 +39,13 @@ 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. + it draws power from one of its USB connections (the one on the + right side when you're looking at the face with the PLX logo). 2. Software requirements: @@ -54,7 +57,7 @@ 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 +75,7 @@ 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 +95,7 @@ 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/