Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750944AbWBWEio (ORCPT ); Wed, 22 Feb 2006 23:38:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750933AbWBWEio (ORCPT ); Wed, 22 Feb 2006 23:38:44 -0500 Received: from xenotime.net ([66.160.160.81]:43175 "HELO xenotime.net") by vger.kernel.org with SMTP id S1750739AbWBWEin (ORCPT ); Wed, 22 Feb 2006 23:38:43 -0500 Date: Wed, 22 Feb 2006 20:39:46 -0800 From: "Randy.Dunlap" To: "Ian McDonald" Cc: trivial@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Documentation: Update to BUG-HUNTING Message-Id: <20060222203946.f698d8ed.rdunlap@xenotime.net> In-Reply-To: References: Organization: YPO4 X-Mailer: Sylpheed version 2.2.0 (GTK+ 2.8.3; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2259 Lines: 59 On Thu, 23 Feb 2006 08:47:39 +1300 Ian McDonald wrote: > Hi there, Lo, > +Finding bugs is not always easy. Have a go though. If you can't find it don't > +give up. Report as much as you have found to the relevant maintainer. See > +MAINTAINERS for who that is for the subsystem you have worked on. or that you are having problems with. > +To debug a kernel, use objdump and look for the hex offset from the crash > +output to find the valid line of code/assembler. Without debug symbols, you > +will see the assembler code for the routine shown, but if your kernel has > +debug symbols the C code will also be available. (Debug symbols can be enabled > +in the kernel hacking menu of the menu configuration.) For example: > + > + objdump -r -S -l --disassemble net/dccp/ipv4.o > + > +NB.: you need to be at the top level of the kernel tree for this to pick up > +your C files. > + > +If you don't have access to the code you can also debug on some crash dumps > +e.g. crash dump output as shown by Dave Miller. > + > +> EIP is at ip_queue_xmit+0x14/0x4c0 > +> ... > +> Code: 44 24 04 e8 6f 05 00 00 e9 e8 fe ff ff 8d 76 00 8d bc 27 00 00 > +> 00 00 55 57 56 53 81 ec bc 00 00 00 8b ac 24 d0 00 00 00 8b 5d 08 > +> <8b> 83 3c 01 00 00 89 44 24 14 8b 45 28 85 c0 89 44 24 18 0f 85 > +> > +> Put the bytes into a "foo.s" file like this: > +> > +> .text > +> .globl foo > +> foo: > +> .byte .... /* bytes from Code: part of OOPS dump */ > +> > +> Compile it with "gcc -c -o foo.o foo.s" then look at the output of > +> "objdump --disassemble foo.o". Maybe add this: You can also take the "Code:"