From owner-freebsd-hackers Sat Feb 3 13:51:54 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id NAA04363 for hackers-outgoing; Sat, 3 Feb 1996 13:51:54 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id NAA04350 for ; Sat, 3 Feb 1996 13:51:46 -0800 (PST) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id WAA10849; Sat, 3 Feb 1996 22:51:37 +0100 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id WAA02093; Sat, 3 Feb 1996 22:51:37 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.7.3/8.6.9) id WAA21349; Sat, 3 Feb 1996 22:29:30 +0100 (MET) From: J Wunsch Message-Id: <199602032129.WAA21349@uriah.heep.sax.de> Subject: Re: How to use DDB to debug a boottime panic? To: scrappy@ki.net (Marc G. Fournier) Date: Sat, 3 Feb 1996 22:29:29 +0100 (MET) Cc: hackers@FreeBSD.ORG Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: from "Marc G. Fournier" at Feb 3, 96 02:40:22 pm X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-hackers@FreeBSD.ORG Precedence: bulk As Marc G. Fournier wrote: > So, I ask here...how do I use DDB? I've read through the man > page for DDB, and got absolutely no where with it. Print out the man page, you'll need it. > being able to use DDB. From the man page, I had assumed that doing something > like: > > print $scbus x/x scbus,10 However p $eax when you wanna know the value of %eax. DDB doesn't have type definitions, it can only handle basic types. > On top of that, I somehow need to step back to get the value > before the call to scsi_attachdevs(), but...'step -1' doesn't do that > either :( Naturally. How should stepping backwards work? You need to set a breakpoint earlier. Remember the -d boot flag (RTFM boot(8)). > If found the GDB examples in the FAQ (or handbook) to be enough to > get me stepping through the kernel and getting the data that was requested, > but have yet to find a similar example for DDB. Look into the handbook again, i once wrote an introduction to using DDB, it is in the section about ``Kernel debugging''. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)