Book Image

Android System Programming

By : Roger Ye, Shen Liu
Book Image

Android System Programming

By: Roger Ye, Shen Liu

Overview of this book

Android system programming involves both hardware and software knowledge to work on system level programming. The developers need to use various techniques to debug the different components in the target devices. With all the challenges, you usually have a deep learning curve to master relevant knowledge in this area. This book will not only give you the key knowledge you need to understand Android system programming, but will also prepare you as you get hands-on with projects and gain debugging skills that you can use in your future projects. You will start by exploring the basic setup of AOSP, and building and testing an emulator image. In the first project, you will learn how to customize and extend the Android emulator. Then you’ll move on to the real challenge—building your own Android system on VirtualBox. You’ll see how to debug the init process, resolve the bootloader issue, and enable various hardware interfaces. When you have a complete system, you will learn how to patch and upgrade it through recovery. Throughout the book, you will get to know useful tips on how to integrate and reuse existing open source projects such as LineageOS (CyanogenMod), Android-x86, Xposed, and GApps in your own system.
Table of Contents (15 chapters)

Removing dependencies on /system

The dependencies to the Android /system folder include two parts:

  • All kernel modules for device drivers are located at: $OUT/system/lib/modules/4.x.x-android-x86.
  • We need to run some basic Linux commands during the recovery boot process. For example, we do hardware initialization using the following command:
    on init
    exec -- /system/bin/logwrapper /system/bin/sh /system/etc/

Let's work on the preceding two points one by one in the following sections.

Hardware initialization in recovery

To load the minimum device drivers needed by recovery, we have to change the execution of the shell script for Android system start. This is a customization process from general to specific, which is different from the goal of the Android...