"At the end of the second article in this series, which outlines
a step-by-step process for embedded Linux development, we had the
LBox up and running, ready to use for application development. On
some occasions, however, the developer needs to modify the
underlying system. Any Linux system can be considered to consist of
three parts: the root filesystem, the kernel image and the
bootloader (the BIOS plays this role in the desktop system).
Typically, we leave the bootloader alone--at least we hope to--and
modify the root filesystem, the kernel image or both..."