[Beowulf] Logging MCE information on next warm boot?

David Mathog mathog at caltech.edu
Tue Jan 26 10:46:40 PST 2010

> David Mathog wrote:
> Will a logger
> message for "kern" test it, or is there some other way to force a
> printk? I'm afraid the logger method might look like it is working, but
> just go through the usual syslog channels instead of netconsole.

Too optimistic. With netconsole (supposedly) running on the local node

  logger -p kern.err "test from me"

only shows up in the log file on that node.  No chance of confusion ;-).
 There is no explicit network logging of kern.err in /etc/syslog.conf,
since I figured syslog is never going to be able to actually log
anything after a kernel error.

dmesg shows that netconsole started and thinks it is working:

netconsole: local port 6666
netconsole: local IP
netconsole: interface eth0
netconsole: remote port 514
netconsole: remote IP
netconsole: remote ethernet address 00:30:48:59:f8:ff
console [netcon0] enabled
netconsole: network logging started

However, absolutely nothing comes over netconsole when a node reboots. 

Searched a lot and finally found out how to test netconsole:

[root at monkey20 rc6.d]# echo 'p' > /proc/sysrq-trigger
[root at monkey20 rc6.d]# echo 't' > /proc/sysrq-trigger
[root at monkey20 rc6.d]# echo 'm' > /proc/sysrq-trigger

and it generated these on the syslogd machine

Jan 26 10:21:12 monkey20.cluster SysRq : 
Jan 26 10:21:12 monkey20.cluster Show Regs 
Jan 26 10:21:35 monkey20.cluster SysRq : 
Jan 26 10:21:35 monkey20.cluster Show State 
Jan 26 10:21:52 monkey20.cluster SysRq : 
Jan 26 10:21:52 monkey20.cluster Show Memory 

Notice the contentless messages, which were the same as on the video
console.  This is a log level issue, change it with dmesg or

[root at monkey20 rc6.d]# echo '9' > /proc/sysrq-trigger
[root at monkey20 rc6.d]# echo 'm' > /proc/sysrq-trigger

and then a pile of memory information shows up on both the syslog side
and the video console.

The default log level on these machines is 3.  If the kernel panics with
it set to that, will the messages that result be "contentless", like the
ones above?


David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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