[PATCH v2 (updated) -mm 4/9] netconsole: Add some useful tips to documentation
From: Satyam Sharma <hidden>
Date: 2007-07-11 04:54:21
[4/9 (updated)] netconsole: Add some useful tips to documentation 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. Cc: Matt Mackall <redacted> Cc: Jesper Juhl <redacted> Signed-off-by: Satyam Sharma <redacted> --- Documentation/networking/netconsole.txt | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) --- diff -ruNp a/Documentation/networking/netconsole.txt b/Documentation/networking/netconsole.txt
--- a/Documentation/networking/netconsole.txt 2007-04-26 08:38:32.000000000 +0530
+++ b/Documentation/networking/netconsole.txt 2007-07-11 03:11:08.000000000 +0530@@ -44,11 +44,35 @@ WARNING: the default target ethernet set ethernet address to send packets, which can cause increased load on other systems on the same ethernet segment. +TIP: some LAN switches may be configured to suppress ethernet broadcasts +so it is advised to explicitly specify the remote agents' MAC addresses +from the config parameters passed to netconsole. + +TIP: to find out the MAC address of, say, 10.0.0.2, you may try using: + + ping -c 1 10.0.0.2 ; /sbin/arp -n | grep 10.0.0.2 + +TIP: in case the remote logging agent is on a separate LAN subnet than +the sender, it is suggested to try specifying the MAC address of the +default gateway (you may use /sbin/route -n to find it out) as the +remote MAC address instead. + 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. +NOTE: if you find that the remote logging agent is not receiving or +printing all messages from the sender, it is likely that you have set the +"console_loglevel" parameter (on the sender) to only send high priority +messages to the console. You can change this at runtime by updating +/proc/sys/kernel/printk appropriately, say by: + + echo 9 > /proc/sys/kernel/printk + +which would send all kernel messages to the console. Refer the proc(5) +man page for more details. + 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