linux - Change default console loglevel during boot up -

i setup centos 6.3 setup, on console loglevel set 4, , default log level set 4. know can change default console log level using following steps:

cat /proc/sys/kernel/printk  4   4   1   7  echo 5 > /proc/sys/kernel/printk cat /proc/sys/kernel/printk  5   4   1   7 

however, upon reboot, console log level reverts original value. need recompile kernel, or there way can changed value persistent across reboot.

do need recompile kernel,

no.

or there way can changed value persistent across reboot.

yes.
use kernel command line parameter loglevel:

loglevel=       kernel messages loglevel smaller                     console loglevel printed console. can                     changed klogd or other programs.                     loglevels defined follows:                      0 (kern_emerg)          system unusable                     1 (kern_alert)          action must taken                     2 (kern_crit)           critical conditions                     3 (kern_err)            error conditions                     4 (kern_warning)        warning conditions                     5 (kern_notice)         normal significant condition                     6 (kern_info)           informational                     7 (kern_debug)          debug-level messages 

the entire list of parameters possible on kernel command line in linux/documentation/kernel-parameters.txt file in source tree.

depending on bootloader (e.g. grub or u-boot), have edit text add new parameter command line. use cat /proc/cmdline view kernel command line used previous boot.