Boot Mode Pins: Boot mode pins provide vital information to ROM code for boot. These pins must be properly set up before power ramp.
Bootstrap: Initial software launched by the ROM code during the memory booting phase.
Boot Header: Optional structure that precedes the initial software and allows the redefinition of the ROM code default settings.
Downloaded software: Initial software
downloaded into on-chip RAM by the ROM code during the peripheral booting
phase.
eFuse: A one-time programmable memory location usually set at the factory.
Flash loader: Downloaded software launched by the ROM code during the preflashing stage. It also programs an image in external memories.
GP device: General-purpose device (SoC) or a non-secure device.
Initial software: Software executed by any of the ROM code mechanisms (memory booting or peripheral booting). Initial software is a generic term for bootstrap and downloaded software. This can be the SBL (secondary bootloader) responsible for loading an OS.
Memory booting: ROM code mechanism that consists of executing initial software from external memory.
Controller CPU: The Arm® Cortex®
CPU for which CPU-ID is 0. It configures the
multicore platform and starts the ROM code to
ensure device booting from a mass storage memory
(memory booting) or a peripheral interface
(peripheral booting).
Peripheral booting: ROM code mechanism that consists of polling selected interfaces, downloading, and executing initial software (in this case, downloaded software) in the internal RAM.
Preflashing: A specific case of peripheral booting where the ROM code mechanism is used to program the external flash memory.
ROM Code: or ROM bootloader (RBL), the on-chip software in device ROM that executes first and implements booting.
ROM Code-controlled Boot Phase: This phase covers the sequence operations from the time the platform releases the reset to the time first user- or customer-owned software starts execution. This phase is fully controlled by the device ROM code.
Booting Parameter Table: A logical structure stored in the on-chip RAM memory and contains information for the boot, such as the boot file name or an address to boot from.