1.. SPDX-License-Identifier: GPL-2.0 2 3============================================ 4Debugging advice for Linux Kernel developers 5============================================ 6 7.. toctree:: 8 :maxdepth: 1 9 10 driver_development_debugging_guide 11 userspace_debugging_guide 12 13.. only:: subproject and html 14 15 Indices 16 ======= 17 18 * :ref:`genindex` 19 20General debugging advice 21======================== 22 23Depending on the issue, a different set of tools is available to track down the 24problem or even to realize whether there is one in the first place. 25 26As a first step you have to figure out what kind of issue you want to debug. 27Depending on the answer, your methodology and choice of tools may vary. 28 29Do I need to debug with limited access? 30--------------------------------------- 31 32Do you have limited access to the machine or are you unable to stop the running 33execution? 34 35In this case your debugging capability depends on built-in debugging support of 36provided distribution kernel. 37The :doc:`/process/debugging/userspace_debugging_guide` provides a brief 38overview over a range of possible debugging tools in that situation. You can 39check the capability of your kernel, in most cases, by looking into config file 40within the /boot directory. 41 42Do I have root access to the system? 43------------------------------------ 44 45Are you easily able to replace the module in question or to install a new 46kernel? 47 48In that case your range of available tools is a lot bigger, you can find the 49tools in the :doc:`/process/debugging/driver_development_debugging_guide`. 50 51Is timing a factor? 52------------------- 53 54It is important to understand if the problem you want to debug manifests itself 55consistently (i.e. given a set of inputs you always get the same, incorrect 56output), or inconsistently. If it manifests itself inconsistently, some timing 57factor might be at play. If inserting delays into the code does change the 58behavior, then quite likely timing is a factor. 59 60When timing does alter the outcome of the code execution using a simple 61printk() for debugging purposes may not work, a similar alternative is to use 62trace_printk() , which logs the debug messages to the trace file instead of the 63kernel log. 64 65**Copyright** ©2024 : Collabora 66