DebuggingProgramCrash

Revision 46 as of 2008-01-19 12:02:34

This document describes how to install debug packages on Ubuntu, which will aid in providing information for bugs.

Feisty Fawn 7.04, Gutsy Gibbon 7.10 and Hardy Heron 8.04

Use this section only if you are using Ubuntu Feisty 7.04, Gutsy 7.10 or Hardy 8.04. See the following section if you are using a prior version.

1. Add the following lines to /etc/apt/sources.list: (of course, replace gutsy with feisty if you're using 7.04 or hardy for 8.04)

Be aware that the development release (Hardy) has no -updates, -proposed or -security repositories.
{{{deb http://ddebs.ubuntu.com gutsy main universe

deb http://ddebs.ubuntu.com gutsy-updates main universe deb http://ddebs.ubuntu.com gutsy-proposed main universe deb http://ddebs.ubuntu.com gutsy-security main universe }}}

: Request: Could this step be explained for the Synaptic Repositories dialog box please?

2. Then run

```
sudo apt-get update
```

to update your package list.

3. The debug symbol packages have the '-dbgsym' suffix attached, so to install the debug symbols for the package 'yelp', you run:

```
sudo apt-get install yelp-dbgsym
```

Alternatively, main Ubuntu repositories could contain '-dbg' debug symbol packages. Those are equivalent to '-dbgsym'. You could use the one you want, but not both.

Now you make a ["Backtrace"].
You can also run ["Valgrind"], if the program crashes with a "Segmentation fault" or "Bus error".
Optionally, you may be asked to produce an ["Strace"].
You can also provide this file : ~/.xsession-errors

References

Announcement: https://lists.ubuntu.com/archives/ubuntu-devel-announce/2006-September/000195.html

Prior Ubuntu versions

Use this section if you are using an Ubuntu version prior to Feisty 7.04.

Check if the package has a debugging version available. In general, debugging packages will be named with a -dbg suffix
If not, you can generally* build one this way:

Something to keep in mind: if you would like to create a build you're going to need to have the relevant deb-src lines in your /etc/apt/sources.list

Install the development scripts:

sudo apt-get install devscripts fakeroot

Find out to which package your program belongs to:
```
dpkg --search <program> 
```
Install the build-time dependencies for the package:
```
sudo apt-get build-dep <package>
```

Build .debs for debugging:

export DEB_BUILD_OPTIONS="debug nostrip noopt"
fakeroot apt-get source -b <package>

Install the needed .debs (they will be in the current working directory if the build succeeded):
```
sudo debi <package>*.changes
```

* Most packages support the build of debugging version in this way. If this process doesn't work for a package, please open a bug against it.

The Xorg server

The X server will by default trap its own crashes and dump a stack trace in /var/log/Xorg.0.log. However, this stack trace is modified by the signal handler itself. To get a "normal" crash, which will trigger a core dump (and apport reporting), add this to your /etc/X11/xorg.conf:

Section "ServerFlags"
        Option "NoTrapSignals" "true"
EndSection

Please see DebuggingXorg for how to debug Xorg server crashes.

Info for the BugSquad

If you're trying to apport-retrace a crash report from a bug that didn't happen on the same Ubuntu release as the one you're running, do the following:

Say that you're running feisty and the crash happened on edgy:

This will create a minimal edgy system.

sudo mkdir -p /chroots/edgy
sudo debootstrap edgy /chroots/edgy/

Now you change into this minimal edgy system.
```
sudo chroot /chroot/edgy
```
edit /etc/apt/sources/list and all the repositories you need, especially Martin's ddeb repository.

apt-get update; apt-get install gdb apport

use apport-retrace as you're used to.

CategoryBugSquad

Ubuntu Wiki