Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (16 chapters)
15
Index

Debugging kernel code

Debugging application code helps you gain insight into the way code works and what is happening when it misbehaves and you can do the same with the kernel, with some limitations.

You can use kgdb for source level debugging, in a manner similar to remote debugging with gdbserver. There is also a self-hosted kernel debugger, kdb, that is handy for lighter weight tasks such as seeing if an instruction is executed and getting the backtrace to find out how it got there. Finally, there are kernel oops messages and panics, which tell you a lot about the cause of a kernel exception.

Debugging kernel code with kgdb

When looking at kernel code using a source debugger, you must remember that the kernel is a complex system, with real-time behaviors. Don't expect debugging to be as easy as it is for applications. Stepping through code that changes the memory mapping or switches context is likely to produce odd results.

kgdb is the name given to the kernel GDB stubs that have been...