Linux kernel - printk level使用說明

1. Printk level說明

#define KERN_EMERG      "<0>"   /* system is unusable                   */
#define KERN_ALERT      "<1>"   /* action must be taken immediately     */
#define KERN_CRIT       "<2>"   /* critical conditions                  */
#define KERN_ERR        "<3>"   /* error conditions                     */
#define KERN_WARNING    "<4>"   /* warning conditions                   */
#define KERN_NOTICE     "<5>"   /* normal but significant condition     */
#define KERN_INFO       "<6>"   /* informational                        */
#define KERN_DEBUG      "<7>"   /* debug-level messages                 */

2. 修改printk level範例

$ echo 7 4 1 7 > /proc/sys/kernel/printk

3. 參數說明

3.1. console_loglevel
Messages with a higher priority than console_loglevel will be printed to the console.

3.2. default_message_level
Messages without an explicit priority will be printed with priority default_message_level.
              
3.3. Minimum_console_loglevel
minimum_console_loglevel is the minimum (highest) value to which console_loglevel can be set.

3.4. Default_console_loglevel
Default_console_loglevel is the default value for console_loglevel.

4. 參考來源
http://elinux.org/Debugging_by_printing