1 2started by Ingo Molnar <mingo@redhat.com>, 2001.09.17 32.6 port and netpoll api by Matt Mackall <mpm@selenic.com>, Sep 9 2003 4 5Please send bug reports to Matt Mackall <mpm@selenic.com> 6 7This module logs kernel printk messages over UDP allowing debugging of 8problem where disk logging fails and serial consoles are impractical. 9 10It can be used either built-in or as a module. As a built-in, 11netconsole initializes immediately after NIC cards and will bring up 12the specified interface as soon as possible. While this doesn't allow 13capture of early kernel panics, it does capture most of the boot 14process. 15 16It takes a string configuration parameter "netconsole" in the 17following format: 18 19 netconsole=[src-port]@[src-ip]/[<dev>],[tgt-port]@<tgt-ip>/[tgt-macaddr] 20 21 where 22 src-port source for UDP packets (defaults to 6665) 23 src-ip source IP to use (interface address) 24 dev network interface (eth0) 25 tgt-port port for logging agent (6666) 26 tgt-ip IP address for logging agent 27 tgt-macaddr ethernet MAC address for logging agent (broadcast) 28 29Examples: 30 31 linux netconsole=4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc 32 33 or 34 35 insmod netconsole netconsole=@/,@10.0.0.2/ 36 37Built-in netconsole starts immediately after the TCP stack is 38initialized and attempts to bring up the supplied dev at the supplied 39address. 40 41The remote host can run either 'netcat -u -l -p <port>' or syslogd. 42 43WARNING: the default target ethernet setting uses the broadcast 44ethernet address to send packets, which can cause increased load on 45other systems on the same ethernet segment. 46 47NOTE: the network device (eth1 in the above case) can run any kind 48of other network traffic, netconsole is not intrusive. Netconsole 49might cause slight delays in other traffic if the volume of kernel 50messages is high, but should have no other impact. 51 52Netconsole was designed to be as instantaneous as possible, to 53enable the logging of even the most critical kernel bugs. It works 54from IRQ contexts as well, and does not enable interrupts while 55sending packets. Due to these unique needs, configuration cannot 56be more automatic, and some fundamental limitations will remain: 57only IP networks, UDP packets and ethernet devices are supported. 58