Filing Kernel Bug reports


The preferred method for reporting a bug against the Ubuntu kernel is done by running the following command from a terminal window (Applications->Accessories->Terminal). It will automatically file an Ubuntu kernel bug in Launchpad. More importantly, it will automatically gather and attach important system information to the bug report.

$ ubuntu-bug linux

The submitter should provide as much information as possible in the bug description:

  1. The majority of kernel bug are hardware specific so be sure to note what hardware/device is being used.
  2. Document any known steps to reproduce the bug.
  3. Also note whether the bug exists in previous kernel versions of Ubuntu or if it's a regression from previous kernel versions.
  4. Finally, it's critical to also make sure to test the latest development Ubuntu kernel version as well as the latest upstream mainline kernel.

If there are any questions about what information to provide, please contact a developer in the #ubuntu-kernel channel on the FreeNode IRC server for help on how to file a bug.

Adding debug info to a bug report

If you didn't file your Ubuntu kernel bug using ubuntu-bug, please run the following which will automatically gather and attach the requested system information to the bug report.

If on a Karmic (or newer release) run:

$ apport-collect -p linux <bug#>

If on Jaunty, please run:

$ apport-collect -p linux-image-`uname -r` <bug#>

As a last resort, at a minimum, your bug report should contain the output of the following commands:

$ uname -a > uname-a.log
$ cat /proc/version_signature > version.log
$ dmesg > dmesg.log
$ sudo lspci -vvnn > lspci-vvnn.log

These four files should be attached separately to the bug report (not pasted into comments or tar and zipped). Please note that dmesg output should be captured as early as possible after bootup to avoid extraneous output.

Reporting Bugs Upstream

Depending on the phase of the Ubuntu release cycle, the Ubuntu kernel team will rebase the Ubuntu kernel with the upstream mainline kernel. Unfortunately, it is sometimes the case that bugs can still exist in the upstream mainline kernel. The upstream kernel has its own bug tracking system at http://bugzilla.kernel.org . If you know your bug exists upstream, you should also report your bug to the upstream kernel bug tracker. It is often the case that once a bug is escalated upstream there is a quick resolution through the help and support of the mainline kernel community. Bug reports in Launchpad can also be set up to monitor bugs reported in other bug tracking systems. The following steps should help you report your bug upstream and monitor it in Launchpad:

  1. Read the guide on reporting bugs for the Linux kernel.

  2. Go to http://bugzilla.kernel.org

  3. Verify your bug does not already exist in the upstream bug tracking system.
    1. If it does exist, please add any useful information that may be lacking in the current report.
      • Link your Launchpad report to the upstream kernel bug report (see step 5).
    2. If your bug does not exist in the upstream bug tracker, proceed to the next step.
  4. Enter your bug report at http://bugzilla.kernel.org/enter_bug.cgi . Follow the instructions on that page.

  5. When creating your bug report be sure to _attach_ any relevant information. This will usually include:
    1. the version of the kernel you are running (uname -r)
    2. dmesg output.
    3. lspci -vvnn output.
    4. If the bug is about interrupts, then /proc/interrupts is also helpful.
    5. If a BIOS issue is suspected, dmidecode output is also helpful.
    6. If the bug is regarding memory oddities, /proc/mtrr info is also helpful.
    7. Most importantly, if this is a regression, the best information you can provide the kernel developers is the information from doing a git bisect. This will hopefully narrow down the exact patch that is causing the regression. The following link will help you through this process.
  6. After you've reported your bug to the kernel bugzilla, remember to set up your Launchpad bug report to monitor the upstream bugzilla report.

Kernel/Bugs (last edited 2012-03-12 17:21:44 by sarvatt)