Techniques Of Cutting For Embedded Linux System Based On Application

Embedded system is defined as a special computer system which takes application as center, bases on computer technology and whose software and hardware can be cut in order to satisfy the severe requirements of the application system such as function, reliability, costs, volume and consumption. With the development of the computer, research and development of embedded system is a light spot at present. Embedded system applies to all kinds of fields and has a good market demands. Among many embedded operating systems, Linux has a lot of characteristic and outstanding advantages which is suitable to many kinds of CPU and hardware platform, reliable performance, good adaption and easy to develop and use. So the research of cutting out to embedded Linux has important value. The main problem of this paper is to research the cutting of embedded Linux system. With the increasing application of embedded system and the development of opensource of Linux, more and more software developers design the embedded system based on Linux. Because embedded Linux system is used in all respects, Linux should be cut to the minimum embedded operating system which has steady performance and intact function under the situation of the special occasions, special applications and suitable embedded hardware environment. What's more, through recombining Linux framework we set up embedded operating system on the goal edition based on original system. This text proceeds from characteristic of embedded Linux operating system at first, putting forward the the necessity studied and commercial opportunity of cuting out the embedded Linux. It also introduced the state of development and characteristic of the embedded operating system of mainstream at present. Embedded Linux will be called protagonist of embedded system, compared with characteristic of embedded Linux system. Accord to the structure of embedded Linux system, a basic embedded operating system should include five parts: 1. Procedure in a guiding role. Implementation system can be fast guide, and function that offer starting the machine in a short time. 2. Linux kernel. Linux kernel is an integral single kernel mode, it made up by five parts which are process running management, memory management, system of the file management, process communication management and interface of the network managing. 3. Initialize the process. The way of operating is in the kernel. While the system just starting, there is only a procedure of initializing running. It does systematic initializing at first, then carry out the procedure of initializing. 4. Hardware driver. The equipment driver is inadvisable part of the kernel, it operate in the kernel mode like other codes in the kernel. 5. Offer the application program of the necessary function. Through the above-mentioned explanation of five items, in order to set up embedded Linux, it need to three important parts including the setting-up kernel, root file system and bootloader In order to simplify hardware environment establish influence in to embedded Linux, the paper selects to make host computer on i386 PC machine, establish embedded Linux system in Flash. This paper introduced how to support other hardware environment at the same time, make the reader that interested in this paper have the leeway to choose hardware environment. This paper constructed that is the instrument chain developing crossed like the compiler, interpreter and the integrated development environment that the embedded system developer needs. Then the papers set up root file system, compile the kernel, set up bootloader by using GNU instrument chain developing over the platform, and finally become embedded Linux system needed. When setting up root file system, we have studied many kinds of files system, such as CRAMFS, JFFS2, EXT2 and RAMDISK. JFFS2 is a successor of JFFS, rewritten again by Red Hat. The full name of JFFS2 is called Journalling Flash System Version 2. The characteristic of JFFS2 that can be written into, being permanences , having dependability when power off, being compressed, etc., make this paper to introduce suitable method of it emphatically, and that is a brilliant point of designing embedded Linux system in this paper.