AOSP Directory Structure for Custom Android Projects

 Introduction 

The Android Open Source Project (AOSP) is meticulously organized to separate each layer and module of the operating system. From hardware drivers to application frameworks, Its folder structure is built for scalability, modularity, and maintainability. For developers looking to build, customize, or optimize Android, understanding this structure is essential 

This blog explores the core directories within AOSP and what role each plays in the Android ecosystem. 

AOSP Directory

 

📂 Key Folders in AOSP Root Directory 

These directories represent the core components that make Android run seamlessly across various devices. 

• frameworks/ 

• hardware/ 

• kernel/ 

• system/ 

• packages/ 

• build/ 

• device/ 

• vendor/ 

Each folder contributes uniquely to the architecture of Android. Let’s explore their purpose. 

 

🧠 frameworks/ – The Brain of Android 

This directory holds the Android framework — the primary layer that applications interact with. 

Noteworthy sections: 

• base/: Houses core services like Activity Manager and Content Providers. These are fundamental for how apps run and interact. 

• opt/: Contains optional frameworks that may be added for features like Bluetooth or advanced networking. 

• native/: Includes native services, written in C/C++, such as SurfaceFlinger, which handles rendering and display. 

• av/: Manages media playback, audio, and video functionalities. 

Use Case: 
If you’re modifying Android UI, application lifecycles, or system services like media or notifications, this is your go-to folder. 

 

🧩 hardware/ – Connecting Android to the Physical World 

This directory handles the interaction between Android and the device's physical hardware. 

Highlights: 

• interfaces/: Defines HAL (Hardware Abstraction Layer) interfaces for hardware components like cameras and audio. 

• libhardware/: Offers the actual implementations of those interfaces. 

• vendor-specific directories: You may find folders like ti/ or qcom/, which are dedicated to particular hardware vendors. 

Use Case: 
Ideal for those working on integrating custom hardware or new hardware features into Android. 

 

⚙️ kernel/ – Powering the Core 

This folder contains configuration and build files necessary to align the Linux kernel with Android requirements. It’s where kernel fragments and configuration metadata are stored, ensuring Android-specific features run correctly. 

Use Case: 
You’ll work here when integrating low-level Linux kernel functionalities or adapting configurations for new hardware. 

 

🧱 system/ – Foundation of Core Services 

The system/ folder contains libraries and utilities that form the backbone of Android’s runtime environment. 

Key subfolders: 

• core/: Contains essential runtime components and libraries like libc and the Android init system. 

• bt/: Implements the Bluetooth stack. 

• netd/: Manages network-related functionalities like IP configuration and routing. 

Use Case: 
Best suited for enhancing low-level system operations, Bluetooth services, or network connectivity. 

 

📦 packages/ – Apps and Services 

This folder holds the source code for system apps and background services that ship with Android. 

Major sections: 

• apps/: Includes stock apps like Settings, Contacts, and Launcher. 

• services/: Hosts background services for telephony, accounts, etc. 

• input/: Manages input devices like touchscreens and keyboards. 

Use Case: 
You’ll navigate here when customizing default apps or creating new system apps for your Android ROM. 

 

🏗️ build/ – The Construction Blueprint 

Everything related to building AOSP resides in this directory. It contains configuration files, environment setups, and Android’s build systems like Soong. 

Use Case: 
Crucial for developers adjusting how Android is compiled, managing dependencies, or integrating custom modules. 

 

📱 device/ – Customizing for Specific Devices 

The device/ directory includes configuration files and data specific to particular Android devices. 

Details: 
Each supported device has its own folder here, containing its hardware configurations, board files, and kernel settings. 

Use Case: 
When porting Android to new hardware or making device-specific tweaks, this is your primary workspace. 

 

🏢 vendor/ – Proprietary & Third-Party Code 

This directory stores proprietary binaries, drivers, HALs, and customizations from hardware vendors. 

Structure: 
Each vendor gets its own subfolder containing their specialized code needed for Android to run on their hardware. 

Use Case: 
You’ll work here when integrating closed-source components or adapting Android to support proprietary features. 

 

✅ Conclusion 

Navigating the AOSP folder structure is a fundamental skill for Android platform development. From tweaking system libraries in system/ to adding new apps in packages/ or managing device-specific builds in device/, each folder serves a targeted purpose. 

By mastering these directories, developers gain greater control over Android customization — enabling innovation across smartphones, tablets, wearables, and IoT devices. 

 

🚀 Ready to Customize AOSP for Your Device? 
At Silicon Signals, we specialize in tailoring Android OS for a variety of platforms. Whether you need BSP development, HAL integration, or full-stack AOSP customization, our team can accelerate your product journey. 

👉 Let Silicon Signals help bring your Android-based innovation to life.