Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758018AbXLSXxS (ORCPT ); Wed, 19 Dec 2007 18:53:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753849AbXLSXxK (ORCPT ); Wed, 19 Dec 2007 18:53:10 -0500 Received: from out4.smtp.messagingengine.com ([66.111.4.28]:50186 "EHLO out4.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428AbXLSXxJ (ORCPT ); Wed, 19 Dec 2007 18:53:09 -0500 X-Greylist: delayed 1302 seconds by postgrey-1.27 at vger.kernel.org; Wed, 19 Dec 2007 18:53:09 EST X-Sasl-enc: 5XUmOk4YaTVNYTrFcNr8ARfH0AAHXXiG9BdaRuRPajxA 1198107086 Subject: RE: printf internals From: Scott Russell To: Siva Prasad Cc: Clemens Koller , David Newall , linux-kernel@vger.kernel.org In-Reply-To: References: <4761E289.9070007@davidnewall.com> <4762AC35.3010706@anagramm.de> Content-Type: text/plain Date: Wed, 19 Dec 2007 18:31:25 -0500 Message-Id: <1198107085.7740.0.camel@oasis.donpoo.home> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1510 Lines: 24 On Wed, 2007-12-19 at 14:33 -0800, Siva Prasad wrote: > Thank you very much for your response Clemens. > > I tried strace on a regular system. It does not show which tty, etc., as it uses the stdout (fd = 1) and write(1, ...) to it. > > This is not a student project. I am trying to build my own kernel and ramdisk. Kernel boots fine to a point where it starts accessing ramdisk and executes init scripts. From there on nothing gets printed. I did some debugging and found that prints of user land programs are not coming to the serial console, while kernel prints are working fine. I found all the programs getting executed, by placing a printk in execve routine and printing the arguments. > > So, I wanted to trace down the path from user program to the kernel and see why it is not printing messages from user program. I placed a printk in drivers/char/tty_io.c:tty_write() and it is not getting called from my file system. I tried the same thing on my good system (say regular PC) and it works as expected. > > Any clues that can help debug this issue is highly appreciated. > How can I get access to the same printf string inside kernel. This sounds like you're printing out the serial console instead. -- Scott AIM: BlueCame1 -- 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/