kernel loglevel

[Wenda Ni]

Thank you so much, Thibaut. I have spotted the source-code logic in
include/linux/prink.h

Cheers,

Wenda Ni, Ph.D.



On Mon, Oct 17, 2016 at 7:41 PM, Thibaut SAUTEREAU <
thibaut.sautereau at telecom-sudparis.eu> wrote:
> On Mon, Oct 17, 2016 at 07:17:32PM -0400, Wenda Ni wrote:
>> Dear all,
>>
>> I am working on a kernel module that incorporate both pr_debug and
>> pr_warn. I would like to see pr_debug messages from dmesg.
>>
>> What I followed is to specify kernel parameter by saying "loglevel=7".
>> This can be seen confirmed  from /proc/cmdline. But still, I donot get
>> pr_debug level messages either from dmesg or from /var/log/messages. I
>> also tried echo 7 > /proc/sys/kernel/printk. It does not return what I
>> expect, either.
>>
>> Let me know what I am missing. Thank you very much in advance.
>>
>> Cheers,
>>
>> Wenda Ni, Ph.D.
>>
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>> Kernelnewbies at kernelnewbies.org
>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
> Hello Wenda,
>
> I encountered the same issue a while ago.
> As stated here: http://elinux.org/Debugging_by_printing
> pr_debug is replaced with an empty statement unless the kernel is compiled
> with DEBUG. So if you just want to play with printing kernel debug logs,
> just define the DEBUG macro in your module source file for testing.
>
> I also observed that without a new line character at the end of the string
> passed to pr_debug, I could not find the log line in dmesg output. Not
sure
> where this comes from.
>
> --
> Thibaut SAUTEREAU
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