The four values in printk denote:

• console_loglevel - messages with a priority higher than this will be printed to the console
• default_message_loglevel - messages without an explicit priority will be printed with this priority
• minimum_console_loglevel - minimum (highest) value to which console_loglevel can be set
• default_console_loglevel - default value for console_loglevel

These values influence printk() behavior when printing or logging error messages. See syslog(2) for more info on the different loglevels.