about printk and console_loglevel

[Andrzej Kardas]

On 05.03.2011 19:42, Siddu wrote:
> Hi all,
> Hi all,
>
> I am little stuck understanding this piece of code below and the way 
> its been working
>
> Question: since KERN_INFO = 6 # which is msg_log_level
> and as per code
> *msg_log_level < console_loglevel*
>
>  this line of printk is not supposed to show up in the dmesg log ? but 
> it is showing up . Why

console_loglevel concern messages that should display on the CONSOLE not 
"dmesg" and controls if message is enough important (read: have prioryty 
below *console_loglevel) *to display it on the console. You must know 
that, kernel logs its messages into buffer (into the RAM) which have 
constant size, when you type dmesg, you simply read messages from that 
buffer (ring-buffer), so that why you see your line in dmesg.

What is more, there is deamon called syslog (rsyslog) which reads this 
buffer periodically and saves messages in appropriate log file on the 
hard drive e.g. /var/log/kern.log or /var/log/messages etc. You can 
configure rsyslog as you wish, to log certain types messages into logfiles.


--
regards
Andrzej Kardas
http://www.linux.mynotes.pl
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