started by Ingo Molnar , 2001.09.17 2.6 port and netpoll api by Matt Mackall , Sep 9 2003 Please send bug reports to Matt Mackall This module logs kernel printk messages over UDP allowing debugging of problem where disk logging fails and serial consoles are impractical. It can be used either built-in or as a module. As a built-in, netconsole initializes immediately after NIC cards and will bring up the specified interface as soon as possible. While this doesn't allow capture of early kernel panics, it does capture most of the boot process. It takes a string configuration parameter "netconsole" in the following format: netconsole=[src-port]@[src-ip]/[],[tgt-port]@/[tgt-macaddr] where src-port source for UDP packets (defaults to 6665) src-ip source IP to use (interface address) dev network interface (eth0) tgt-port port for logging agent (6666) tgt-ip IP address for logging agent tgt-macaddr ethernet MAC address for logging agent (broadcast) Examples: linux netconsole=4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc or insmod netconsole netconsole=@/,@10.0.0.2/ Built-in netconsole starts immediately after the TCP stack is initialized and attempts to bring up the supplied dev at the supplied address. The remote host can run either 'netcat -u -l -p ' or syslogd. WARNING: the default target ethernet setting uses the broadcast ethernet address to send packets, which can cause increased load on other systems on the same ethernet segment. NOTE: the network device (eth1 in the above case) can run any kind of other network traffic, netconsole is not intrusive. Netconsole might cause slight delays in other traffic if the volume of kernel messages is high, but should have no other impact. Netconsole was designed to be as instantaneous as possible, to enable the logging of even the most critical kernel bugs. It works from IRQ contexts as well, and does not enable interrupts while sending packets. Due to these unique needs, configuration can not be more automatic, and some fundamental limitations will remain: only IP networks, UDP packets and ethernet devices are supported.