Default console loglevel (1-15)

configname: CONFIG_CONSOLE_LOGLEVEL_DEFAULT

Linux Kernel Configuration
└─>Kernel hacking
└─>printk and dmesg options
└─>Default console loglevel (1-15)
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Default loglevel to determine what will be printed on the console.

Setting a default here is equivalent to passing in loglevel=<x> in
the kernel bootargs. loglevel=<x> continues to override whatever
value is specified here as well.

Note: This does not affect the log level of un-prefixed printk()
usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
option.