3.2. Android Bootloaders

Getting toolchain for u-boot builds

The toolchains are automatically downloaded by the build scripts.

Install OPTEE-OS build dependencies

Check OPTEE-OS docs to know list of dependencies needed to be installed : https://optee.readthedocs.io/en/latest/building/prerequisites.html

Install additional dependencies

$ sudo apt install bc bison build-essential curl u-boot-tools flex git libssl-dev python3 python3-pip wget -y
$ pip3 install pycryptodome pyelftools shyaml --user

3.2.1. Downloading sources

Fetch the code using repo:

$ mkdir ${YOUR_PATH}/ti-bootloader-aosp/ && cd $_
$ repo init -u https://git.ti.com/git/android/manifest.git -b android15-release -m releases/RLS_10_01_Bootloader.xml
$ repo sync

For more information about repo, visit Android’s official documentation

3.2.2. Build Instructions

  1. Build bootloaders images using:

    $ cd ${YOUR_PATH}/ti-bootloader-aosp/
$ ./build/build_all.sh --config=build/config/boards/am62x-sk.yaml

    This will generate all the required bootloaders in out/am62x-sk/release:

    $ tree out
out/am62x-sk/
└── release
    ├── bl31-release.bin
    ├── tee-release.bin
    ├── tiboot3-release-gp.bin
    ├── tiboot3-release-hsfs.bin
    ├── tispl-release.bin
    └── u-boot-release.img

    These binaries are valid for an AM62X SoC. To build for other boards, look at build/config/boards. We can see the following valid combinations:

    Name

    Description

    am62p-sk-dfu.yaml

    AM62Px board with DFU boot enabled (usage with snagboot)

    am62p-sk.yaml

    AM62Px board (regular eMMC boot)

  2. From out/am62x-sk/release, copy the tiboot3.bin, tispl.bin and u-boot.img generated to $YOUR_PATH/ti-aosp-15/vendor/ti/am62x/bootloader.

    If not copied, the prebuilt bootloader binaries already present in vendor/ti/am62x/bootloader will get used by flashall.sh flashing script.

    For picking the correct filenames, refer to the upstream documentation.

  3. Finally, rebuild Android by following Build Instructions.

Warning

If you also modify Trusted Applications (TA), it’s recommended to use the release_android.sh script to avoid copying all the TAs manually as it’s quite error prone.

3.2.3. Release Instructions

In addition to building and copying manually to $YOUR_PATH/ti-aosp-15, it’s also possible to automatically build all supported variants and copy them to Android.

Assuming Android has already been downloaded following Downloading sources, This can be done using:

$ cd ${YOUR_PATH}/ti-bootloader-aosp/
$ ./build/release_android.sh --aosp=${YOUR_PATH}/ti-aosp-15 --commit
# [...] lots of build logs later

After that, rebuild Android by following Build Instructions to use the new bootloaders.

Tip

To only release for a particular board, pass the --config option to release_android.sh.