http://newandroidbook.com/Articles/aboot.html
>Android's boot process starts with the firmware*, which loads from a ROM. The exact details of the firmware boot vary between devices and specific architectures (e.g. Qualcomm vs. NVidia).
>As discussed in the book, the standard aboot is derived from the "LittleKernel" project
https://github.com/littlekernel/lk/wiki/Introduction
>LK is the Android bootloader and is also used in Android Trusted Execution Environment - "Trusty TEE" Operating System.
https://source.android.com/security/trusty/
>Trusty is a set of software components supporting a Trusted Execution Environment (TEE) on mobile devices.
>A TEE processor is typically a separate microprocessor in the system or a virtualized instance of the main processor. The TEE processor is isolated from the rest of the system using memory and I/O protection mechanisms supported by the hardware.
>TEE processors have become a mainstay in today's mobile devices. The main processor on these devices is considered "untrusted" and cannot access certain areas of RAM, hardware registers and fuses where secret data (such as device-specific cryptographic keys) is stored by the manufacturer. Software running on the main processor delegates any operations that require use of secret data to the TEE processor.
So from what I gather from the surface;
>Most major SoC makers implement on-chip firmware
>The on-chip firmware consists of an instance of LittleKernel
>LittleKernel supplies the first and second stage bootloaders for Android
>It is also constantly running on a dedicated security processor inside the SoC using TrustZone extensions as part of Trusty OS
>It is responsible for handling cryptographic data and DRM
>All TrustZone processors help implement an "ARM Trusted Firmware" which includes AMDs use of TrustZone
Thoughts?