No matter how you approach it, Linux debugging will always be complex. The first part of this Short Cut examines some of these complexities as they relate to kernel debugging and present ideas and methods to improve your debugging skills, inside the kernel itself and then inside device drivers. You begin by learning to use Kernel GNU Debugger (KGDB) to probe the kernel. But because you cannot debug very early kernel startup code with KGDB, we also show you how to work with a hardware debug probe. For the examples in this section, we use a unit manufactured by Abatron called the BDI-2000. Hardware debug probes are often called JTAG probes, because they use a low-level communications method first employed for boundary scan testing of integrated circuits defined by the Joint Test Action Group (JTAG).

----------- In the second part of this Short Cut, we continue our coverage of GDB for debugging application code in user space. We extend our coverage of remote debugging and the tools and techniques used for this peculiar debugging environment.

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This Short Cut includes Chapters 14 and 15 from the book Embedded Linux Primer by Christopher Hallinan (0-13-167984-8). As such, it contains references to earlier and later chapters that are not included in this Short Cut. Apart from these references, the Short Cut is fully self-contained and is an excellent choice for embedded Linux developers interested in learning both kernel-level and application-level debugging techniques.

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Kernel Debugging Techniques

14.1----Challenges to Kernel Debugging----4

14.2----Using KGDB for Kernel Debugging----6-----

14.3----Debugging the Linux Kernel----14-

14.4----Hardward-Assisted Debugging----53

14.5--- When It Doesn't Boot----63

14.6--- Chapter Summary----69

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Debugging Embedded Linux Applications

15.1--- Target Debugging----72

15.2--- Remote (Cross) Debugging----73

15.3--- Debugging with Shared Libraries----80

15.4--- Debugging Multiple Tasks----87

15.5--- Additional Remote Debug Options----97

15.6--- Chapter Summary----99