From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268858AbUHUHk3 (ORCPT ); Sat, 21 Aug 2004 03:40:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268829AbUHUHk3 (ORCPT ); Sat, 21 Aug 2004 03:40:29 -0400 Received: from mx1.redhat.com ([66.187.233.31]:46277 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S268858AbUHUHkX (ORCPT ); Sat, 21 Aug 2004 03:40:23 -0400 Subject: Re: Dumping kernel log (dmesg) and backtraces after a panic From: Arjan van de Ven Reply-To: arjanv@redhat.com To: Chris Johns Cc: linux-kernel@vger.kernel.org, kaos@oss.sgi.com In-Reply-To: References: Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-R2A3eFGSTIL24JMStuK2" Organization: Red Hat UK Message-Id: <1093074013.2792.3.camel@laptop.fenrus.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) Date: Sat, 21 Aug 2004 09:40:13 +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-R2A3eFGSTIL24JMStuK2 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Sat, 2004-08-21 at 04:21, Chris Johns wrote: > We're using Red Hat EL3 Linux (2.4.21 base kernel plus 300 or so Red=20 > Hat and/or community patches) and I'm dearly missing KDB already, since=20 > we previously used 2.4.21 from kernel.org and applied the appropriate=20 > KDB patch(es). Now with EL3, I'm not even sure what the right patch for=20 > KDB would be. >=20 > The problem is how to debug a hang or panic without KDB. Specifically,=20 > I'd like to dump out real backtraces of all (or selected) processes=20 > instead of the pseudo-backtraces that the panic or Alt-Sysrq-t=20 > provides, and I'd like to dump out the kernel log buffer (dmesg) after=20 > a hang or panic. >=20 > When I say "pseudo-backtraces", it seems that the oops/sysrq processing=20 > picks everything that looks like a text address from the stack of each=20 > thread (or the thread that caused the panic) and formats it, rather=20 > than walking the stack back correctly like KDB's 'bt' command does. And=20 > I don't know of any way of getting the 'dmesg' output after a=20 > hang/panic other than by using KDB. why not use netdump and then analyze the dump on another machine with "crash" (a gdb variant) ? --=-R2A3eFGSTIL24JMStuK2 Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQBBJvxdxULwo51rQBIRAkTHAJ9/LJYubNp3UxKrkWobgc7xJ6LeegCgqJnk hFX8AjBRQaPUfr9C4PIiD5g= =fqnl -----END PGP SIGNATURE----- --=-R2A3eFGSTIL24JMStuK2--