Date: Sat, 30 Dec 2006 19:25:54 +0100 From: Karol Kwiatkowski <freebsd@orchid.homeunix.org> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-stable@freebsd.org Subject: debugging kernel options (was: Re: 6.2-PRE: Fatal Trap?) Message-ID: <4596AF32.2060205@orchid.homeunix.org> In-Reply-To: <20061230170358.K50974@fledge.watson.org> References: <20061230035722.L39715@thebighonker.lerctr.org> <20061230151933.P18740@fledge.watson.org> <20061230093730.I47579@thebighonker.lerctr.org> <20061230160353.K18740@fledge.watson.org> <45969487.1020806@orchid.homeunix.org> <20061230170358.K50974@fledge.watson.org>
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[-- Attachment #1 --] 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 [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFlq85ezeoPAwGIYsRCBUOAJsFI/lbuQvWutIJ8g+Zd2hXrtf6jgCgkb5f XuD4X9BBFiBC4lA7wj+Wodk= =ZUn6 -----END PGP SIGNATURE-----
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