Ubuntu Wiki

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

Hardy 8.04 and Newer

Use this section only if you are using Ubuntu Hardy 8.04 or more recent versions. How to determine your version. See the following section if you are using a prior version.

First, check if there is a package with a -dbg suffix in the main Ubuntu repositories. These are the debug symbol packages, and are equivalent to '-dbgsym' described below. You can safely use either one, but not both at once.

If not:

1. Create an /etc/apt/sources.list.d/ddebs.list file with the following lines:

   echo "deb http://ddebs.ubuntu.com $(lsb_release -cs) main restricted universe multiverse" |
   sudo tee -a /etc/apt/sources.list.d/ddebs.list

Furthermore, stable releases (not alphas and betas) require the following three lines:

• echo "deb http://ddebs.ubuntu.com $(lsb_release -cs)-updates main restricted universe multiverse 
  deb http://ddebs.ubuntu.com $(lsb_release -cs)-security main restricted universe multiverse
  deb http://ddebs.ubuntu.com $(lsb_release -cs)-proposed main restricted universe multiverse" |
  sudo tee -a /etc/apt/sources.list.d/ddebs.list

  You may also add these lines using the Synaptic Package Manager:

  • Choose Synaptic via the System > Administration menu.

  • Choose Software Sources or Repositories via the Settings menu, and click on the Third-Party Software tab.

  • Click the Add button and enter each deb ... line as above one by one and click the Add Source button (you will have to add these lines one at a time).

• Import the debug symbol archive signing key:

  sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 428D7C01 5E0577F2

• Then run

  sudo apt-get update

  to update your package list or click the Reload button if you used the Synaptic Package Manager.

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

  apt-cache policy yelp

This will show you the version number currently installed (we'll use 2.22.1-0ubuntu2.8.04.1 in this example). Then, you can then run the following to install the debug symbols:

• sudo apt-get install yelp-dbgsym=2.22.1-0ubuntu2.8.04.1

You can also use the Synaptic Package Manager to search for 'yelp-dbgsym' and install it from there.

Remember that 'yelp' [which is the package name of "Help and Support" located under the 'System' menu] is just an example and not a part of the command. It is just used to demonstrate the procedure. You will have to replace 'yelp' with the name of the package you want to debug.

1. Now you make a Backtrace.

2. You can also run Valgrind, if the program crashes with a "Segmentation fault" or "Bus error".

3. Optionally, you may be asked to produce an Strace.

4. You can also provide this file : ~/.xsession-errors

How do we remove all this stuff after getting the trace and get back to a normal system?

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 Gutsy 7.10.

1. Check if the package has a debugging version available. In general, debugging packages will be named with a -dbg suffix

2. 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

1. Install the development scripts:

   sudo apt-get install devscripts fakeroot

2. Find out to which package your program belongs to:

   dpkg --search <program> 

3. Install the build-time dependencies for the package:

   sudo apt-get build-dep <package>

4. Build .debs for debugging:

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

5. 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 Gutsy and the crash happened on Feisty:

1. This will create a minimal feisty system.

   sudo mkdir -p /chroots/feisty
   sudo debootstrap feisty /chroots/feisty/

2. Now you change into this minimal feisty system.

   sudo chroot /chroots/feisty

3. edit /etc/apt/sources/list and all the repositories you need, especially Martin's ddeb repository.

4. apt-get update; apt-get install gdb apport

5. use apport-retrace as you're used to.

For more information on dealing with bug reports Apport see Bugs/ApportRetraces.

CategoryBugSquad CategoryDebugging