debugging kernel options (was: Re: 6.2-PRE: Fatal Trap?)

[Karol Kwiatkowski]

Robert Watson wrote:
>> P.S. out of curiosity - now that I have configured kernel with DDB and
>> KDB options, is there any performance penalty of running such kernel?
> 
> No, it shouldn't really have any effect on performance.  The one thing
> to watch out for is that your system will no longer reboot automatically
> on a panic, as it will drop to the debugger, by default.  You can change
> this by setting debug.debugger_on_panic to 0, in which case you will
> likely want to set debug.trace_on_panic to 1 so it prints a stack trace
> before rebooting (which is often sufficient, combined with the trap
> frame and panic message to debug the problem).
> 
> Right now these are sysctls, not tunables, but you can change the
> default using options KDB_UNATTENDED (which flips the default to not
> entering the debugger and rebooting) and options KDB_TRACE (which causes
> a trace to be printed on panic by default).  Probably they should also
> be tunables so that loader.conf entries will work.

Great explanation, thank you. I turned on debugging on my desktop
computer which, apart from normal every day use, is 'testing' STABLE by
running it :) I'm perfectly fine with the defaults, at least for now.

Cheers and thanks again,

Karol

-- 
Karol Kwiatkowski  <freebsd at orchid dot homeunix dot org>
OpenPGP: http://www.orchid.homeunix.org/carlos/gpg/0x06E09309.asc

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