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driver core: basic infrastructure for per-module dynamic debug messages

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Base infrastructure to enable per-module debug messages.

I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes
control of debugging statements on a per-module basis in one /proc file,
currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG,
is not set, debugging statements can still be enabled as before, often by
defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no
affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set.

The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That
is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls
can be dynamically enabled/disabled on a per-module basis.

Future plans include extending this functionality to subsystems, that define 
their own debug levels and flags.

Usage:

Dynamic debugging is controlled by the debugfs file, 
<debugfs>/dynamic_printk/modules. This file contains a list of the modules that
can be enabled. The format of the file is as follows:

	<module_name> <enabled=0/1>
		.
		.
		.

	<module_name> : Name of the module in which the debug call resides
	<enabled=0/1> : whether the messages are enabled or not

For example:

	snd_hda_intel enabled=0
	fixup enabled=1
	driver enabled=0

Enable a module:

	$echo "set enabled=1 <module_name>" > dynamic_printk/modules

Disable a module:

	$echo "set enabled=0 <module_name>" > 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.

[gkh: minor cleanups and tweaks to make the build work quietly]

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jason Baron
2008-08-12 16:46:19 -04:00
committed by Greg Kroah-Hartman
parent 33376c1c04
commit 346e15beb5
14 changed files with 700 additions and 7 deletions
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55
lib/Kconfig.debug
View File

@@ -807,6 +807,61 @@ menuconfig BUILD_DOCSRC
Say N if you are unsure.
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:
<module_name> <enabled=0/1>
.
.
.
<module_name> : Name of the module in which the debug call resides
<enabled=0/1> : 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 <module_name>" > dynamic_printk/modules
Disable a module:
$echo "set enabled=0 <module_name>" > 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.
source "samples/Kconfig"
source "lib/Kconfig.kgdb"