From owner-cvs-all@FreeBSD.ORG Wed Jan 21 17:50:21 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E07E316A4CF for ; Wed, 21 Jan 2004 17:50:21 -0800 (PST) Received: from root.org (root.org [67.118.192.226]) by mx1.FreeBSD.org (Postfix) with SMTP id B499143D53 for ; Wed, 21 Jan 2004 17:50:12 -0800 (PST) (envelope-from nate@root.org) Received: (qmail 5134 invoked by uid 1000); 22 Jan 2004 01:50:14 -0000 Date: Wed, 21 Jan 2004 17:50:14 -0800 (PST) From: Nate Lawson To: Bruce Evans In-Reply-To: <20040122123454.V10548@gamplex.bde.org> Message-ID: <20040121174709.W5097@root.org> References: <200401210148.aa95501@salmon.maths.tcd.ie> <20040120203001.B99547@root.org> <20040120144505.ccsc4kog4c88sgww@www.sweetdreamsracing.biz> <20040121235215.GV86671@wantadilla.lemis.com> <20040122123454.V10548@gamplex.bde.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: cvs-src@FreeBSD.org cc: Ian Dowse cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: backtrace() and the console log (was Re: cvs commit: src/sys/alpha...) X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Jan 2004 01:50:22 -0000 On Thu, 22 Jan 2004, 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. And...... cut! We're right back at the part where Ian says "hey, here's a patch" and then I say "hey, here's how to only dump non-DDB data to the message buffer" and then Bruce says "ok by me". Now we skip to the part where Ian commits it. -Nate (Oh, and I forgot the epilogue where the panic line numbers disappear because the backtrace is more useful. :)