From Fedora Project Wiki

Configure syslog to log kernel debug messages

In standard configuration system logger does not log kernel debug messages. Usually this is not a problem as debug messages can be read by dmesg. However kernel internal dmesg buffer is limited (on Fedora limit is 512KB), only most recent messages can be read from the buffer. When lot of information is printed, it can be lost. Below configuration allow to log all kernel messages to /var/log/kernel file.

  • Add this line in /etc/rsyslog.conf
kern.*                                                  /var/log/kernel
  • Restart services
/etc/init.d/rsyslog restart

Configure syslog to debug kernel and wpa_supplicant

Sometimes is needed to have kernel debug messages together with wpa_supplicant logged in one place. Below changes allow to do this.

  • Edit /etc/sysconfig/wpa_supplicant file to log into /var/log/messages
OTHER_ARGS="-u -f /var/log/messages -dd -P /var/run/"
  • Edit /etc/rsyslog.conf file to log all kernel messages into /var/log/messages
kern.*;*.info;mail.none;authpriv.none;cron.none                /var/log/messages
  • Restart services
/etc/init.d/wpa_supplicant restart
/etc/init.d/rsyslog restart

Configure syslog for debug kernel and wpa_supplicant together with NetworkManager

Requires settings from above and below changes.

  • Edit /etc/init.d/NetworkManager file to enable verbose debug
daemon --pidfile $pidfile --check $servicename $processname --pid-file=$pidfile --log-level=DEBUG
  • Restart services
/etc/init.d/NetworkManager restart