repeatable kernel freeze

Bill Davidsen davidsen at
Fri Jun 18 20:19:54 UTC 2010

Joe Conway wrote:
> On 06/16/2010 05:39 PM, Sam Varshavchik wrote:
>> Based on the assumption that you are experiencing a kernel crash, there
>> are two ways of obtaining diagnostics:
>> 1) A serial console. Going retro, getting a null-modem adapter, and
>> connecting the serial port of the ailing machine with the serial port on
>> another machine, adding the "console" parameter to the kernel boot
>> prompt, and redirecting console messages through the serial port to
>> another machine where you'll run minicom to capture the incoming serial
>> port data. Hopefully, if your kernel is oopsing or crashing, you will be
>> able to obtain a log a useful dump.
> I actually tried this a while back, but this machine has no serial port,
> and USB-to-rs232 did not seem to work.
>> 2) Using kexec-tools to set up a recovery kernel. Adding the crashkernel
>> parameter to your kernel boot prompt, reserving 128MB of your RAM for a
>> recovery kernel and a small boot image. When your running kernel
>> crashes, the recovery kernel, installed by kexec-tools, is going to
>> generate a kernel dump, which can then be grokked by crash to generate a
>> dump.
>> In either case, you have a fair bit of RTFMing to do.
>> And then after wasting all the time, you'll discover that you're not
>> getting a useful crash in the first place.
> Hmmm, you paint a rosy picture ;-)
> But if I do nothing, my choices are:
> 1) hope to get lucky on some future kernel update
> 2) buy new hardware
> 3) live with not using scp or rsync over ssh
> Maybe it's time for a hardware upgrade....
I do just such a backup nightly between machines, and no lockups on machines 
from fc9 to fc13. Something in you hardware is possibly tickling the problem.

Possible solution, add a remote syslog line to syslog.conf and keep a copy of 
your logs elsewhere. If the hang is in network won't work, clearly. Serial 
console and such might help, watching from a text console might help. All low 
effort and cost.

Of course, any excuse to go upgrade...

Bill Davidsen <davidsen at>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

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