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 (22 chapters)
Mastering Embedded Linux Programming
About the Author
About the Reviewers

Using TFTP to load the kernel

When working with real hardware such as the BeagleBone Black, it is best to load the kernel over the network, especially when the root filesystem is mounted via NFS. In this way, you are not using any local storage on the device. It saves time if you don't have to keep re-flashing the memory and means that you can get work done while the flash storage drivers are still being developed (it happens).

U-Boot has supported the Trivial File Transfer Protocol (TFTP) for many years. Firstly, you need to install a tftp daemon on your development machine. On Ubuntu, you would install the tftpd-hpa package, which grants read access to files in the directory /var/lib/tftpboot to tftp clients like U-Boot.

Assuming that you have copied zImage and am335x-boneblack.dtb into /var/lib/tftpboot, enter these commands into U-Boot to load and boot:

setenv serverip
setenv ipaddr
tftpboot 0x80200000 zImage
tftpboot 0x80f00000 am335x-boneblack.dtb
setenv npath...