Date: Thu, 22 Jan 2004 12:41:25 +1030 From: Greg 'groggy' Lehey <grog@FreeBSD.org> To: Bruce Evans <bde@zeta.org.au> Cc: cvs-all@FreeBSD.org Subject: Re: backtrace() and the console log (was Re: cvs commit: src/sys/alpha...) Message-ID: <20040122021124.GH86671@wantadilla.lemis.com> In-Reply-To: <20040122123454.V10548@gamplex.bde.org> References: <200401210148.aa95501@salmon.maths.tcd.ie> <20040120203001.B99547@root.org> <20040121162731.F7489@gamplex.bde.org> <20040120144505.ccsc4kog4c88sgww@www.sweetdreamsracing.biz> <200401210148.aa95501@salmon.maths.tcd.ie> <20040121235215.GV86671@wantadilla.lemis.com> <20040122123454.V10548@gamplex.bde.org>
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--QN0KHc3254GHvltB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thursday, 22 January 2004 at 12:43:40 +1100, Bruce Evans wrote: > On Thu, 22 Jan 2004, Greg 'groggy' Lehey wrote: > >> On Wednesday, 21 January 2004 at 16:40:46 +1100, Bruce Evans wrote: >>> On Tue, 20 Jan 2004, Nate Lawson wrote: >>> >>>> On Wed, 21 Jan 2004, Ian Dowse wrote: >>>>> I've been using the following patch for a while to get backtrace() >>>>> to output to the kernel message buffer. Sending all ddb output via >>>>> printf might be undesirable for some cases, but I guess having it >>>>> configurable with a `debug.ddb_use_printf' sysctl that defaults to >>>>> the old behaviour would be ok? >>> >>> It's undesireable in almost all cases, since it fills up the message >>> buffer with garbage. >> >> If it's "garbage", why are we ever producing it? Currently I'm >> getting a lot of LORs which don't get reported anywhere. I'd really >> like to catch this "garbage". > > Because it is hard to debug when the debugger doesn't print any output. > In almost all cases, you don't want to record all the false trails that > you followed tracking down a problem, especially since any recording might > cycle more important records out of the message buffer before syslogd(8) > has a chance to run. Ah, OK. You're talking about the complete ddb output. I was talking about automatically generated backtraces. Agreed, you don't want to be reminded of the roundabout way you get to a solution. Greg -- See complete headers for address and phone numbers. --QN0KHc3254GHvltB Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.0 (FreeBSD) iD8DBQFADzFMIubykFB6QiMRAg2oAJ9iwl5sFXZbq87hyabe7Gq9AAHNTQCeLqoK 6iZFN/Vkccng35rJeEOz6lQ= =3/0e -----END PGP SIGNATURE----- --QN0KHc3254GHvltB--
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