Android Booting Process
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To add to what Android bootloader/fastboot mode and recovery mode explained/Android boot process has provided, I want to give some more details from Bootloader of normal boot to Kernel.
Bootloader of normal boot / PBL (primary bootloader)
The program is saved inside and run by the CPU and provided by the CPU manufacturer. It cannot be customized by a developer.
SBL (Secondary Bootloader)
Normally it is provided by the device manufacture / OEM. While Primary boot loader doesn't mean the first stage of a boot loader, and secondary boot loader doesn't mean the second stage of a boot loader.
RPM (Resource & Power Manager)
Normally it is provided by the device manufacture / OEM.
TZ (Trust Zone)
LK (Little Kernel)
- init hardware module
- update cmdline and distinguish the startup mode
- select and update device tree
- setup system status and prepare to init the Kernel