HAL

What is HAL?

Hardware abstraction layer, HAL. A HAL defines a standard interface for hardware vendors to implement, which enables Android to be agnostic about low-level driver implementations.
HAL implementations are packaged into modules and loaded by the Android system at the appropriate time.
Using a HAL allows you to implement functionality without affecting or modifying the higher level system.

Android stack

Governance philosophy

• Originated by OHA (Open Handset Alliance), which is led by Google.
  Android is intentionally and explicitly an open source effort.
• Fisrt and foremost, the Android philosophy is pragmatic. The objective is a shared product that each contributor can tailor and customize.
• Anyone can use the Android source code for any purpose.
• Android Compatibility Program, maintained by AOSP, which is led by Google.

Android Architecture