Mastering Embedded Linux Programming - Second Edition

Phase 3 – TPL

Now, at last, we are running a full bootloader, such as U-Boot or BareBox. Usually, there is a simple command-line user interface that lets you perform maintenance tasks, such as loading new boot and kernel images into flash storage, and loading and booting a kernel, and there is a way to load the kernel automatically without user intervention.

The following diagram explains the phase 3 architecture:

At the end of the third phase, there is a kernel in memory, waiting to be started.

Embedded bootloaders usually disappear from memory once the kernel is running, and perform no further part in the operation of the system.