In-depth analysis of the Android Startup Process

• What happened when I press the power key of the Android device?
• What is the Startup Process of Android?
• What is Linux kernel?
• What is the difference between the Desktop Linux kernel and the Android Linux kernel?
• What is a bootstrap loader?
• What is Zygote?
• What are X86 and ARM linux?
• What is init. rc?
• What is system service?

When we think about the Android startup process, there are always a lot of questions in our minds. This article introduces the Android startup process and hopes to help you find the answers to these questions.

Android is an open-source Linux-based operating system. X86x86 is a series of intel 8086 CPU-based computer microprocessor instruction set architectures. It is the most common system for Linux kernel deployment. However, all Android devices run on ARM processor ARM derived from advanced, streamlined Instruction Set machine, derived from ARM architecture), except intel Xolo devices (http://xolo.in/xolo-x900-features ). Xolo source self-propelled 1.6 GHz x86 processor. The Startup Process of Android devices or embedded devices or linux-based ARM devices is slightly different from that of the desktop version. In this article, I will explain the Startup Process of Android devices. Going deep into the linux Startup Process is a good article about the Desktop linux Startup Process.

After you press the power switch, the Android device performs the following steps.

Step 1: Start Power Supply and system startup

When the power supply is down, the boot chip CODE starts to solidify in ROM from a predefined place. Load the Bootstrap program to RAM and then execute it.

Step 2: Bootstrap program

The Bootstrap program is a small program before the Android operating system starts running. The boot program is the first program to run, so it is for a specific motherboard and chip. Device manufacturers either use popular boot programs such as redboot, uboot, and qi bootloader, or develop their own boot programs, which are not part of the Android operating system. The pilot program is the place where the OEM or operator locks and limits.

The Bootstrap program is executed in two phases. In the first stage, it detects external RAM and loads programs useful for the second stage. In the second stage, it guides the program to set the network and memory. These are necessary to run the kernel. To achieve special goals, the boot program can set the kernel according to the configuration parameters or input data.

The Android Bootstrap can be found in\bootable\bootloader\legacy\usbloaderFind.

Files contained by traditional loaders must be described here: