How to change the printk level?

Dear sir:

If i want to print all the level kernel message printed by printk in the kernel source code , how to modify?
For example, if i want to print (KERN_INFO, KERN_DEBUG, KERN_ERR), how to modify?

echo $level > /proc/sys/kernel/printk


What is the meaning of “$level” ?

You can use google search to find an answer when it is not tegra related issue.

For example, Message logging with printk — The Linux Kernel documentation