On Sat, 03 Aug 2013 20:27:55 +0800, Woody Wu said: > Hi, > > My kernel is printing too many messages at boot time from a special > device driver (j2ffs filesystem). I belive these kernel messages are > level DEBUG. If don't change the kernel code, is there anyway to print > only some higher level of messages?
In your kernel source tree, there's a file called
Documentation/kernel-parameters.txt
and in it, we find documentation of the following two boot-time parameters:
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
We also add it as printk module parameter, so users
could change it dynamically, usually by
/sys/module/printk/parameters/ignore_loglevel.
...
loglevel= All Kernel Messages with a loglevel smaller than the
console loglevel will be printed to the console. It can
also be changed with klogd or other programs. The
loglevels are defined as follows:
0 (KERN_EMERG) system is unusable
1 (KERN_ALERT) action must be taken immediately
2 (KERN_CRIT) critical conditions
3 (KERN_ERR) error conditions
4 (KERN_WARNING) warning conditions
5 (KERN_NOTICE) normal but significant condition
6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages
In addition, there may or may not be a module parameter to control the
logging level of the particular module - look for the word 'debug' in that
file. There's also the 'dynamic debugging' facility which the module may
be coded to support....
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