A quick tour of the bootloader
As stated, at the beginning of this chapter, using the serial console, we can get access to the bootloader.
Actually, the BeagleBone Black has two bootloaders: one named SPL, which is the prebootloader that initializes the hardware components, such as the RAM and some mass storage devices, and the second named U-Boot, which is the real bootloader that initializes almost all the peripherals and has support for, among other things, booting over a network, and a scriptable shell through which basic commands can be given. Now the one million dollar question is: why should a developer be able to manage the bootloader too?
Well, the answers are more than one, however, the most important are as follows:
- By passing a well-formed command line to the kernel, we can change some functionalities in the running filesystem.
- From the bootloader, we can easily manage a factory restore method (this is usually made with a hidden button in a tiny hole on the system's box. By...
