In the first Ice Cream Sandwich source code that was released, the Hardware Abstraction Layer (HAL) – the software layer giving applications direct access to the hardware components – was to some extent adapted for a Texas Instruments hardware platform. However, for all 2011 Xperia phones, we used a Qualcomm hardware platform. This means we have to replace the default HAL coming with first source code released for Ice Cream Sandwich, with our own HAL.
The HAL changes have impact on several features on a phone, including the camera, different sensors (such as proximity, light, accelerometer and compass), audio, Bluetooth, Wi-Fi, GPS, as well as multimedia and graphics components. Thus, we do not only have to modify and configure the HAL according to the Qualcomm hardware platform, but also all the other hardware components used in a phone.
Wow, I sure hope they're just mixing up terminology here. The entire point of a HAL is that you just plug in your drivers. If you have to modify the HAL because you're using different hardware than the reference device, you're doing it wrong.