From owner-freebsd-questions@FreeBSD.ORG Tue May 10 17:29:54 2011 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5BDF9106566B for ; Tue, 10 May 2011 17:29:54 +0000 (UTC) (envelope-from dhaneshkk@hotmail.com) Received: from blu0-omc4-s35.blu0.hotmail.com (blu0-omc4-s35.blu0.hotmail.com [65.55.111.174]) by mx1.freebsd.org (Postfix) with ESMTP id 258458FC08 for ; Tue, 10 May 2011 17:29:53 +0000 (UTC) Received: from BLU154-W43 ([65.55.111.136]) by blu0-omc4-s35.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Tue, 10 May 2011 10:17:52 -0700 Message-ID: X-Originating-IP: [117.193.140.245] From: dhaneshk k To: Date: Tue, 10 May 2011 17:17:51 +0000 Importance: Normal MIME-Version: 1.0 X-OriginalArrivalTime: 10 May 2011 17:17:52.0637 (UTC) FILETIME=[31E0D2D0:01CC0F36] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Subject: kgdb and vmcore.0 cannot access memory at 0x252d1 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 May 2011 17:29:54 -0000 list=2C I am new to kernel debugging=2C I compiled a new kernel with opti= ons KDB and DDB in addition to the GENERIC config and booted with the = new kernel.( Goal is to debug the coredumps in my laptops /var/crash/vmc= ore files and try to find and fix the panic/situation which produce these = coredumps) I tried to analyze all of the vmcore files in my /var/crash/vmcore.= x core dumps steps done after booting into the new kernel # cd /usr/obj/usr/src/sys/MYCUSTORMKERNEL #kgdb kernel.debug /var/crash/vmcore.0 kgdb kernel.debug /var/crash/vmcore.0 GNU gdb 6.1.1 [FreeBSD] Copyright 2004 Free Software Foundation=2C Inc. GDB is free software=2C covered by the GNU General Public License=2C and yo= u are welcome to change it and/or distribute copies of it under certain condition= s. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-marcel-freebsd"... Cannot access memory at address 0x252d1 (kgdb)=20 (kgdb)=20 For all the vmcore files I am getting this output.. Cannot access me= mory at address 0x252d1=2C how can I proceed from here=2C=20 How to debug what is happening=2C what makes the kernel to dump these v= mcores and fix the issue by using further debugging.. what are the next steps =2C if there a message in kgdb "Cannot access m= emory at address 0x252d1 or any address" =20 Please share your suggestion and hints to debug more from this point. I a= m stuck here.. Thanks in advance Dhanesh =