From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1461 invoked by alias); 10 Nov 2009 18:38:21 -0000 Received: (qmail 1425 invoked by uid 22791); 10 Nov 2009 18:38:19 -0000 X-SWARE-Spam-Status: No, hits=0.0 required=5.0 tests=AWL,BAYES_00,SPF_PASS,TVD_RCVD_IP X-Spam-Check-By: sourceware.org Received: from 207-172-212-176.c3-0.smr-ubr2.sbo-smr.ma.static.cable.rcn.com (HELO torpor.static.net) (207.172.212.176) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 10 Nov 2009 18:38:12 +0000 Received: from ita4fw1.itasoftware.com ([63.107.91.99] helo=jknight.internal.itasoftware.com) by torpor.static.net with esmtpa (Exim 4.69) (envelope-from ) id 1N7vbV-0005fI-Tr; Tue, 10 Nov 2009 13:38:10 -0500 Subject: Re: Troubles with debug info, using systemtap on debian. Mime-Version: 1.0 (Apple Message framework v1076) Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes From: James Y Knight In-Reply-To: <20091110093254.GA3190@localhost.localdomain> Date: Tue, 10 Nov 2009 18:38:00 -0000 Cc: systemtap@sourceware.org Content-Transfer-Encoding: 7bit Message-Id: References: <20091110093254.GA3190@localhost.localdomain> To: Eugeniy Meshcheryakov X-Spam-Score: -10.0 X-Spam-Report: ALL_TRUSTED=-10 X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q4/txt/msg00485.txt.bz2 On Nov 10, 2009, at 4:32 AM, Eugeniy Meshcheryakov wrote: >> probe module("autofs4").function("autofs4_fill_super") {} > I never saw systemtap segfaulting. I do not have autofs4 module, but i > tried with snd module and it works. What version of > systemtap/libelf1/libdw1 do you use? After seeing the segfaults, I compiled both systemtap and elfutils from latest git head, as of yesterday. Same segfaults. Before that, I was using: systemtap 1.0-2 libelf/etc 0.143-1 The segfaults only occur if the installed module is stripped of debug data (which it usually is), and if the debug data itself is stripped of code. That is the case with the files debian's kernel-package installs into /usr/lib/debug/*.ko, but I'm led to believe is not the case with the files that Fedora installs into /usr/lib/debug/*.ko.debug. Unless something *further* strange is going on in my environment, anyone should be able to reproduce by: 1) removing the symlink to your kernel build dir (rm /lib/modules/ $VERS/build): renaming is not enough, systemtap still finds it! 2) ensuring that the debug info in /usr/lib/debug is stripped of code with objcopy --only-keep-debug. 3) ensuring the kernel modules in /lib/modules/$VERS are stripped of debug info. I'd certainly be interested if people can't reproduce this, so I can look further to try to figure out what else might be a triggering factor... >> 3) The debian kernel's debuginfo does "objcopy --only-keep- >> debug"...That seems like it shouldn't cause systemtap to blow up, >> but it does. I guess that's a known bug? > No it is not. At least not for me. When I was discussing this on IRC "przemoc86" mentioned that debuginfo stripped of code might not be currently supported. In any case, a segfault seems poor, whether or not it's supposed to be supported. :) James