loglevel 7 (debug) and pr_debug()

[Arun KS]

Hi Martin,

On Wed, Apr 16, 2014 at 2:46 PM, Martin Kepplinger <martink at posteo.de>
wrote:
> Am 2014-04-16 11:00, schrieb Arun KS:
>> Hi Martin,
>>
>> On Wed, Apr 16, 2014 at 2:13 PM, Martin Kepplinger <martink at posteo.de>
wrote:
>>> I'm on Debian here and I don't really get pr_debug and printk(KERN_DEBUG
>>> ...). Let's stick to pr_debug.
>>>
>>> I have DYNAMIC_DEBUG enabled and
>>> root at laptop:/proc/sys/kernel# cat /proc/sys/kernel/printk
>>> 7       7       1       7
>> This shows the console log level.
>> This file controls the traffic to console. But all the log messages
>> will be present in logbuf.
>
> How do I view debug messages from logbuf?
>
>>
>>>
>>> I write a module with pr_debug's. I load the module and I *don't* see
>>> anything in /var/log/messages (or anywhere in /var/log/* ). Adding
>>> #define DEBUG doesn't help.
>>>
>>> /sys/kernel/debug/dynamic_debug/control has the pr_debug entries I use
>>> in my loaded module.
>>>
>>> In short: How do I see debug log messages? Using pr_info() works as
>>> expected. What am I missing? Do I need to edit my Makefile?
>> Did you enable dynamic printing for your file?
>>
>> Below command enables dynamic printing for file sdhci.c.
>> echo 'file sdhci.c +p' > /sys/kernel/debug/dynamic_debug/control
>
> well. I tried that. The thing is, the pr_debug() symbols are in
> "control" only after "insmod my_module". Then I can echo -n 'file
> my_mobule.c +p' > control
> But my pr_debug() messages get printed directly after insmod, basically
> in my module_init function. Enabling my file doesn't output anything in
> /var/log/*
So now you know why your pr_debug is absent in logbuf.

You can make your module as a built in and use bootargs.

eg:
dyndbg="file your_filename.c +p"

Thanks,
Arun


>
>>
>>
>> Thanks,
>> Arun
>>>
>>> thanks!
>>>                      martin
>>>
>>> --
>>> Martin Kepplinger
>>> e-mail        martink AT posteo DOT at
>>> chat (XMPP)   martink AT jabber DOT at
>>>
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