On 02-Jan-01 The Hermit Hacker wrote:
> Over the past several months, as others have reported, I've been getting
> system hangs using 5.0-CURRENT w/ SMP ... I've got DDB enabled, but
> ctl-alt-esc doesn't break me to the debugger ...
> I'm not complaining about the hangs, if I was overly concerned, I'd run
> -STABLE, but I'm wondering how one goes about providing debug information
> on them other then through DDB?

Not easily. :(  If you can make the problem easily repeatable, then you can try
turning on KTR in your kernel (see NOTES, you will need KTR_EXTEND), setting up
a serial console that you log the output of, create a shell script that runs
the following commands:


sysctl -w debug.ktr_mask=0x1208
sysctl -w debug.ktr_verbose=2


and run the script.  You probably want to run it over a tty or remote login so
tthat the serial console output is just the logging (warning, it will be very
verbose!).  Also, you probably want to use
http://www.FreeBSD.org/~jhb/patches/mtx_quiet.patch to shut up most of the
irrelevant and cluttery mutex trace messages.  Note that having this much
logging on will probably slow the machine to a crawl as well, so you may have
to just start this up and go off and do something else until it hangs. :-/ 
Another alternative is to rig up a NMI debouncer and use it to break into the
debugger.  Then you can start poking around to see who owns sched_lock, etc.

> Thanks ...


John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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