The Design And Implementation Of NOR Flash-based Embedded Linux File System

Due to its open-source of Linux Kernel ,free transplantation and development ,even its free applications and so on, Linux has been developing steadily in the embedded development area. Then embedded file system,as an important part of embedded linux, because of embedded devices'storage medium, the special nature of the power supply and limited resources, and other requirements, makes its importance more prominent.This paper is based on a project ,which is to develop a NOR Flash-based embedded Linux file system to adapt to the developed video server based on TI Davinci. As some special characteristics of embedded devices, making embedded file system in addition to meet the general file system's basic requirements, there are some characteristics of their own. We build the embedded Linux file system in order to make kenel can perform well on it, in addition , the file system's size would be streamlined and configuration files would also be optimized to meet the requirements of embedded systems. The article described in detail the steps and methods used to create a simple root file system, in addition,the simple root file system needs further improvement. The read-only file system cramfs, this paper puts forward a programme to add user and modify their password,and has successfully applied to the development of the file system. As to embedded Linux in the MTD equipment, developers need their own hands to add MTD software package to the embedded Linux systems in order to achieve the Flash storage device management. In order to build a good embedded file system, we need to debug them, the paper applies Uboot's NFS function to debug the file system and used mkcramfs tool to make cramfs image file ,and then use the programming features of Uboot to burn the root file system into MTD device.And then from the system installation, system login, configuring system parameters, the system services and operation, system upgrading ,shutting down and rebooting the system this six aspects,we test the embedded file system's function ,robust and performance. Since file system needs improving and changing in the development ,the paper also introduce a method to use wget of Busybox to download the update files from the web server ,and apply MTD Flash erase and copying tools to burn the update file into flash device.The file system we built has been successfully applied to the development of the video server and achieved good results. However, due to not using shadow document, the user login passwords are not using shadow mechnisim. Therefore, the security of the system sill there are problems exist, we need to further improve and perfect the system of this document. In addition, the Flash file system occupy much space,this does not meet the requirements of embedded system's efficient use of resources, therefore, to streamline the file system is also an important work to be done in future.