Shulou(Shulou.com)06/02 Report--

This article mainly introduces "the startup process of the Android system". In the daily operation, I believe that many people have doubts about the startup process of the Android system. The editor consulted all kinds of materials and sorted out a simple and easy-to-use operation method. I hope it will be helpful to answer the doubts about the startup process of the Android system. Next, please follow the editor to study!

1. Schematic diagram of Android system startup process

Startup process: Loader-> Kernel-> Native-> Framework-> App.

2. Android system startup process

Loader

The execution of the Loader layer is divided into two steps:

1. After the Android device is powered on, the boot chip executes the boot code solidified in Boot ROM and loads the Boot Loader code into memory.

2. The Boot Loader code starts execution, checks the RAM, completes the hardware initialization, and loads the Linux kernel code into memory.

Kernel

The Linux kernel starts to boot, initializes various software and hardware environments, loads drivers, mounts the root file system, and executes init programs.

Native

1. Init processes fork user daemons such as logd, healthd, installd, adbd, etc.

two。 Start ServiceManager and MediaServer (local service)

3. Fork sends out the Zygote process, and the Zygote process is the parent process of all Java processes.

Framework

The Framework layer consists of the C++ Framework layer and the Java Framework layer.

C++ Framework layer

C++ Framework layer mainly runs local services, namely MediaServer process, which is derived from init process fork and is responsible for starting and managing the entire C++ framework, including AudioFlinger, Camera Service and other services.

Java Framework layer

The Java Framework layer mainly runs the SystemServer process, the SystemServer process is the first Java process out of the Zygote process fork, SystemServer is responsible for starting and managing Java Framework, and mainly manages Android services, such as ActivityManagerService, NotificationManagerService, WindowManagerService, etc., all of which run in the SystemServer process in the form of threads.

App

The first App process fork out of the Zygote process is Launcher, the desktop App, and all App processes are generated by the Zygote process fork.

At this point, the study of "the startup process of the Android system" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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