Android Booting Process

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android-booting-process

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.

  1. 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.

  2. 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.

    primary and secondary boot loaders

  3. RPM (Resource & Power Manager)

    Normally it is provided by the device manufacture / OEM.

  4. TZ (Trust Zone)

    Hardware-backed Keystore
    Trusty

  5. 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
    • fastboot
    • authorization
  6. Kernel

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