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authorSatyam Sharma <satyam@infradead.org>2007-08-10 18:31:19 -0400
committerDavid S. Miller <davem@sunset.davemloft.net>2007-10-10 19:48:04 -0400
commit8d4ef88b5df1afe097e38aef8cab2ed35ca141ea (patch)
treed99fa45a05ce8ab304f2aa7e4253d61d23cbeeeb /Documentation/networking/netconsole.txt
parent0cc120bea1d4ba3893a26c70d271e89f928b8a97 (diff)
[NET] netconsole: Add some useful tips to documentation
Based upon initial work by Keiichi Kii <k-keiichi@bx.jp.nec.com>. Add some useful general-purpose tips. Also suggest solution for the frequent problem of console loglevel set too low numerically (i.e. for high priority messages only) on the sender. Signed-off-by: Satyam Sharma <satyam@infradead.org> Acked-by: Keiichi Kii <k-keiichi@bx.jp.nec.com> Acked-by: Matt Mackall <mpm@selenic.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking/netconsole.txt')
-rw-r--r--Documentation/networking/netconsole.txt25
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diff --git a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt
index 1caa6c734691..5962f45815a2 100644
--- a/Documentation/networking/netconsole.txt
+++ b/Documentation/networking/netconsole.txt
@@ -44,11 +44,36 @@ WARNING: the default target ethernet setting uses the broadcast
44ethernet address to send packets, which can cause increased load on 44ethernet address to send packets, which can cause increased load on
45other systems on the same ethernet segment. 45other systems on the same ethernet segment.
46 46
47TIP: some LAN switches may be configured to suppress ethernet broadcasts
48so it is advised to explicitly specify the remote agents' MAC addresses
49from the config parameters passed to netconsole.
50
51TIP: to find out the MAC address of, say, 10.0.0.2, you may try using:
52
53 ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2
54
55TIP: in case the remote logging agent is on a separate LAN subnet than
56the sender, it is suggested to try specifying the MAC address of the
57default gateway (you may use /sbin/route -n to find it out) as the
58remote MAC address instead.
59
47NOTE: the network device (eth1 in the above case) can run any kind 60NOTE: the network device (eth1 in the above case) can run any kind
48of other network traffic, netconsole is not intrusive. Netconsole 61of other network traffic, netconsole is not intrusive. Netconsole
49might cause slight delays in other traffic if the volume of kernel 62might cause slight delays in other traffic if the volume of kernel
50messages is high, but should have no other impact. 63messages is high, but should have no other impact.
51 64
65NOTE: if you find that the remote logging agent is not receiving or
66printing all messages from the sender, it is likely that you have set
67the "console_loglevel" parameter (on the sender) to only send high
68priority messages to the console. You can change this at runtime using:
69
70 dmesg -n 8
71
72or by specifying "debug" on the kernel command line at boot, to send
73all kernel messages to the console. A specific value for this parameter
74can also be set using the "loglevel" kernel boot option. See the
75dmesg(8) man page and Documentation/kernel-parameters.txt for details.
76
52Netconsole was designed to be as instantaneous as possible, to 77Netconsole was designed to be as instantaneous as possible, to
53enable the logging of even the most critical kernel bugs. It works 78enable the logging of even the most critical kernel bugs. It works
54from IRQ contexts as well, and does not enable interrupts while 79from IRQ contexts as well, and does not enable interrupts while