The PSP on-chip bootloader is a piece of immutable code executed when the PSP boots.
When the machine boots (cold or warm start), the PSP starts executing the on-chip bootloader.
It locates and parse the Embedded Firmware Structure and the PSP directory table in the flash.
It loads and verifies the off-chip bootloader and starts executing it.
The off-chip bootloader has several functions:
- initialize some devices
- execute the ABL code (mainly used to initialize DRAM and PCI)
- load the SMU firmware
- load the BIOS and boot the x86 cores
- at the end, start executing the fTPM.