Basic concepts of ARM's embedded Linux porting experience

The basic concept of ARM's embedded Linux porting experience-general Linux technology-Linux programming and kernel information. The following is a detailed description. ARM is short for Advanced RISC Machines (a processor of Advanced and streamlined command systems). It is a microprocessor intellectual property (IP) Core provided by ARM.

ARM has been applied in various product markets, including industrial control, consumer electronic products, communication systems, network systems, and wireless systems. ARM-based microprocessor applications occupy a market share of more than 75% of 32-bit Proteus microprocessors. Uncover your cell phone, MP3, PDA, and hey, most of them have an ARM-based microprocessor!

Several ARM Kernel series (such as ARM7, ARM9E, ARM10E, SecurCore, Xscale, and StrongARM) can meet the needs of different application fields and penetrate embedded systems into every corner. This is an era of ARM!

Some people have the rivers and lakes ("Wulin rumor") and some embedded systems have the ARM. To build a complex embedded system, hardware alone is not enough. We also need to port the operating system. We usually Build Windows CE, Linux, and Palm OS on the ARM platform, among which Linux has the advantages of open source code. Recently, as the project owner of an Embedded ARM (hardware)/Linux (software) system, I led the project team to do the following:

(1) circuit board design based on the ARM920T kernel S3C2410A CPU;

(2) Build the underlying software platform for ARM processing:
　　
A. Port Bootloader;
B. transplantation of the embedded Linux operating system kernel;
C. Create an embedded Linux root file system;
D. Write the peripheral Linux driver on the circuit board.

This article will truly repeat the experiences of the author during the development of this project, so as to share with the readers. The first chapter briefly introduces the hardware design of the ARM Development Board, the second chapter analyzes the Bootloader porting method, and the third chapter describes the transplantation of embedded mizi Linux and the construction of file systems, chapter 4 describes the peripheral driver design. Chapter 5 provides an example of application development on a constructed software and hardware platform.

If you have an Embedded System Development Foundation, you can easily understand the content described in this article. Even if you have never experienced the development of embedded systems, this article will not be a raw one. You can contact the author via email below: 21cnbao@21cn.com.

2. ARM Architecture

ARM microprocessor is a typical feature of the server architecture. It also has the following enhancements:

(L) In each data processing instruction, the arithmetic logical unit (ALU) and the er are controlled to maximize the utilization of ALU and er;

(2) The addressing mode of auto increment and auto increment to optimize the loop in the program;

(3) Load and Store multiple commands at the same time to increase data throughput;

(4) All commands are executed in a condition to increase the execution throughput.

The ARM architecture is 32 characters long and supports Byte (8 bits), Halfword (16 bits), and Word (32 bits) data types.

Most applications run in User mode. When the processor is in User mode, the executed program cannot access some protected system resources or change the mode. Otherwise, an exception occurs. The use of system resources is controlled by the operating system.

Other User modes are also called privileged modes. They can fully access system resources and change the mode freely. FIQ, IRQ, supervisor, Abort, and undefined modes are also called exception modes. The system enters these modes when handling specific exceptions. These five exception modes have their own additional registers to avoid conflicts with programs in user mode when exceptions occur.

Another mode is the system mode. Any exception will not lead to this mode, and it uses the same registers as the User mode. It is a privileged mode for operating system tasks that have access to system resource requests and need to avoid using additional registers.