Pre-configuration
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      How to overload default or device-specific Android HALs

      This knowledge base article explains how to overload default or device-specific Android HALs included into emteria.OS with a user-specified HAL implementation. This empowers the user to customize their devices. Additional information on how to create a custom HAL based on Androids Health HAL can be found in the Android Documentation.

      Note: This currently only works on Raspberry Pi 4 based devices.

      1. Extend the cmdline.txt at the boot partition with androidboot.product.board=<product-name>

        Eg. for our Health HAL this is:

        androidboot.product.board=emteria

        This could also be done through system properties.

      2. Create a prebuild of the HAL you want to overload with the naming scheme <HAL-name>.<product-name>.so.

        Eg. for the Health HAL we will create:

        android.hardware.health@2.1-impl-emteria.so
      3. Boot up your device.
      4. Copy the prebuild onto the odm partition.

        This can be done through adb.
        Place the prebuild under:

        /lib/hw or lib64/hw
      5. Reboot the device.
        The standard HAL should now be overloaded.