| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | |
| 2 | started by Ingo Molnar <mingo@redhat.com>, 2001.09.17 |
| 3 | 2.6 port and netpoll api by Matt Mackall <mpm@selenic.com>, Sep 9 2003 |
| 4 | |
| 5 | Please send bug reports to Matt Mackall <mpm@selenic.com> |
| 6 | |
| 7 | This module logs kernel printk messages over UDP allowing debugging of |
| 8 | problem where disk logging fails and serial consoles are impractical. |
| 9 | |
| 10 | It can be used either built-in or as a module. As a built-in, |
| 11 | netconsole initializes immediately after NIC cards and will bring up |
| 12 | the specified interface as soon as possible. While this doesn't allow |
| 13 | capture of early kernel panics, it does capture most of the boot |
| 14 | process. |
| 15 | |
| 16 | It takes a string configuration parameter "netconsole" in the |
| 17 | following 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 | |
| 29 | Examples: |
| 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 | |
| 37 | Built-in netconsole starts immediately after the TCP stack is |
| 38 | initialized and attempts to bring up the supplied dev at the supplied |
| 39 | address. |
| 40 | |
| 41 | The remote host can run either 'netcat -u -l -p <port>' or syslogd. |
| 42 | |
| 43 | WARNING: the default target ethernet setting uses the broadcast |
| 44 | ethernet address to send packets, which can cause increased load on |
| 45 | other systems on the same ethernet segment. |
| 46 | |
| 47 | NOTE: the network device (eth1 in the above case) can run any kind |
| 48 | of other network traffic, netconsole is not intrusive. Netconsole |
| 49 | might cause slight delays in other traffic if the volume of kernel |
| 50 | messages is high, but should have no other impact. |
| 51 | |
| 52 | Netconsole was designed to be as instantaneous as possible, to |
| 53 | enable the logging of even the most critical kernel bugs. It works |
| 54 | from IRQ contexts as well, and does not enable interrupts while |
| 55 | sending packets. Due to these unique needs, configuration can not |
| 56 | be more automatic, and some fundamental limitations will remain: |
| 57 | only IP networks, UDP packets and ethernet devices are supported. |