Linux kernel error levels (Value, Name and Meanings)

Error level value	Error level name	Meaning
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