From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932493AbZACSsx (ORCPT ); Sat, 3 Jan 2009 13:48:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758904AbZACSsn (ORCPT ); Sat, 3 Jan 2009 13:48:43 -0500 Received: from nf-out-0910.google.com ([64.233.182.189]:53228 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758704AbZACSsm (ORCPT ); Sat, 3 Jan 2009 13:48:42 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references:x-google-sender-auth; b=xJI28PfVgGiwJht9eVN1+asi9TzhrAR33B3Qgccoqj49O8nPJxgdescRyxgKzmIgRN TtBqHa17b6eTbaG+nUZDUu5lbAJ2d3td5PCxZM8KIfJ4Bebm/oC3VgF3KfXBv4Ru5+Fn 4DNYOV1vTe7Q1hGEIsmOZ8S3Szrt7BJFnpcec= Message-ID: <517f3f820901031048p36e65f92l20bb7250cc4d82e5@mail.gmail.com> Date: Sun, 4 Jan 2009 07:48:39 +1300 From: "Michael Kerrisk" To: "Jason Baron" Subject: Re: dynamic_printk documentation Cc: "Tilman Schmidt" , linux-kernel@vger.kernel.org, "Michael Kerrisk" In-Reply-To: <20081223162229.GB4126@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <4950D8B5.5040404@phoenixsoftware.de> <20081223162229.GB4126@redhat.com> X-Google-Sender-Auth: e20ed2d884fddce4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 24, 2008 at 5:22 AM, Jason Baron wrote: > On Tue, Dec 23, 2008 at 01:25:25PM +0100, Tilman Schmidt wrote: >> Where is the current debugfs interface to dynamic_printk documented? >> From the source in lib/dynamic_printk.c I deduced that >> >> echo "set enable=1 " > /sys/kernel/debug/dynamic_printk/modules >> >> should enable debug output for module , and verified >> experimentally that this does indeed work. Is that already described >> somewhere I just overlooked? If not, I would propose creating a file >> Documentation/dynamic_printk.txt. >> >> Thanks, >> Tilman > > hi, > > Most of it is with the config parameter definition in lib/Kconfig.debug > (copied below). I can propose copying it into Documentation/ if you think it'd > be useful. That would make some sense. Kconfig isn't usually the place where where one expects to look for usage documentation. Cheers, Michael > config DYNAMIC_PRINTK_DEBUG > bool "Enable dynamic printk() call support" > default n > depends on PRINTK > select PRINTK_DEBUG > help > > Compiles debug level messages into the kernel, which would not > otherwise be available at runtime. These messages can then be > enabled/disabled on a per module basis. This mechanism implicitly > enables all pr_debug() and dev_dbg() calls. The impact of this > compile option is a larger kernel text size of about 2%. > > Usage: > > Dynamic debugging is controlled by the debugfs file, > dynamic_printk/modules. This file contains a list of the modules that > can be enabled. The format of the file is the module name, followed > by a set of flags that can be enabled. The first flag is always the > 'enabled' flag. For example: > > > . > . > . > > : Name of the module in which the debug call resides > : whether the messages are enabled or not > > From a live system: > > snd_hda_intel enabled=0 > fixup enabled=0 > driver enabled=0 > > Enable a module: > > $echo "set enabled=1 " > dynamic_printk/modules > > Disable a module: > > $echo "set enabled=0 " > dynamic_printk/modules > > Enable all modules: > > $echo "set enabled=1 all" > dynamic_printk/modules > > Disable all modules: > > $echo "set enabled=0 all" > dynamic_printk/modules > > Finally, passing "dynamic_printk" at the command line enables > debugging for all modules. This mode can be turned off via the above > disable command. > > -- > 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/ > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Found a documentation bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html