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1da177e4 LT |
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 | |
84eb8d06 | 55 | sending packets. Due to these unique needs, configuration cannot |
1da177e4 LT |
56 | be more automatic, and some fundamental limitations will remain: |
57 | only IP networks, UDP packets and ethernet devices are supported. |