Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756943Ab1F1HMn (ORCPT ); Tue, 28 Jun 2011 03:12:43 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:50563 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756728Ab1F1HKc (ORCPT ); Tue, 28 Jun 2011 03:10:32 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=XCehEYM3mKbPVblhrC6+JZtHdWM3Qt/3Adx+l8Uk5DRU6ysXeT2qihdhnfNHNbj/g7 8LbDc3dZv7/7vCDOlBIYv/dGn9JI+er4tA1+zmKRsZDlkvjT1sL+EbdehJs8IjNCq6C1 vAZOt9MChCOi8Ux79W66OdpZhlPqe3BcRzqYA= From: Jim Cromie To: linux-kernel@vger.kernel.org Cc: gnb@fmeh.org, jbaron@redhat.com, bvanassche@acm.org, gregkh@suse.de, Jim Cromie Subject: [PATCH 11/11] dynamic_debug: document use of pendinq queries at boot-time Date: Tue, 28 Jun 2011 01:09:52 -0600 Message-Id: <1309244992-2305-12-git-send-email-jim.cromie@gmail.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1309244992-2305-1-git-send-email-jim.cromie@gmail.com> References: <1309244992-2305-1-git-send-email-jim.cromie@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2828 Lines: 60 Add paragraph that pendinq-queries are checked when modules are loaded, so debug statements can be used in module_init functions. Signed-off-by: Jim Cromie --- Documentation/dynamic-debug-howto.txt | 20 ++++++++++++++------ 1 files changed, 14 insertions(+), 6 deletions(-) diff --git a/Documentation/dynamic-debug-howto.txt b/Documentation/dynamic-debug-howto.txt index d0faf98..49b75b81 100644 --- a/Documentation/dynamic-debug-howto.txt +++ b/Documentation/dynamic-debug-howto.txt @@ -120,11 +120,12 @@ specifications, followed by a flags change specification. command ::= match-spec* flags-spec -The match-spec's are used to choose a subset of the known dprintk() +The match-specs are used to choose a subset of the known dprintk() callsites to which to apply the flags-spec. Think of them as a query -with implicit ANDs between each pair. Note that an empty list of -match-specs is possible, but is not very useful because it will not -match any debug statement callsites. +with implicit ANDs between each pair. This means that multiple specs +of a given type are nonsense; a module cannot match A and B +simultaneously. Note that an empty list of match-specs is legal but +pointless, it will not match any debug statement callsites. A match specification comprises a keyword, which controls the attribute of the callsite to be compared, and a value to compare against. Possible @@ -242,13 +243,20 @@ QUERY follows the syntax described above, but must not exceed 1023 characters. The enablement of debug messages is done as an arch_initcall. Thus you can enable debug messages in all code processed after this arch_initcall via this boot parameter. -On an x86 system for example ACPI enablement is a subsys_initcall and -ddebug_query="file ec.c +p" + +On an x86 system for example ACPI enablement is a subsys_initcall, so + ddebug_query="file ec.c +p" will show early Embedded Controller transactions during ACPI setup if your machine (typically a laptop) has an Embedded Controller. PCI (or other devices) initialization also is a hot candidate for using this boot parameter for debugging purposes. +You can also give queries for modules which are not yet loaded, but +will be, via udev or /etc/modules. These queries are saved to a +pending-queries list, and are applied when the module is loaded, and +before the module's init function is invoked. Note that modules which +have no debug messages do not trigger this, so queries for them will +remain on the pending-list until reboot. Examples ======== -- 1.7.4.1 -- 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/