【作者】 郑桦；

【导师】 刘清；

【作者基本信息】 武汉理工大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 文件系统是操作系统最基本的资源，它是一个计算机系统内文件和目录的集合。随着嵌入式系统硬件设备的广泛运用、其价格的不断降低以及嵌入式系统应用范围的不断扩大，嵌入式操作系统的重要性显得更加突出，嵌入式文件系统的开发也引起了更广泛的关注。由于系统的结构和应用要求的不同，嵌入式的文件系统在很多方面都与桌面文件系统有较大的区别，主要体现在实时响应、可移植性、可裁剪性和可配置性等方面。本文就是在一个标准Linux文件系统的体系结构的基础上，进行相应的裁剪和配置，并移植到一个手持式电脑产品的硬件平台中，从而实现了一个专用的嵌入式Linux的文件系统。本文首先对嵌入式系统、Linux系统进行了简单介绍，然后引出了二者结合的产物——嵌入式Linux系统，并分析了其特点、优势和目前国内外的研究情况；而后介绍了Linux文件系统的布局和层次结构，对Linux系统中主要和重要的文件进行了说明，为后来的裁剪工作打下了基础；然后详细描述了本文作者所参与设计的一个可信移动终端产品上的嵌入式Linux文件系统的整个构造过程，仔细分析了在设计过程中如何选择和配置所需的系统文件，以及如何设置文件系统的用户和组的权限来使系统达到一定的安全性能；最后，本文概述了如何搭建嵌入式开发平台，以帮助其他开发人员能够在已构造好的基本文件系统之上进行进一步的开发。本文所构造的嵌入式Linux文件系统秉承了标准Linux文件系统的树型目录结构，但根据实际的硬件限制和产品要求，进行了很大程度的精简，只保留了系统启动运行所需的最基本的一些文件，并对所选取的每一个文件的内容也尽量简化，以保证嵌入式系统精小的要求。另外优化了文件系统的物理布局，将常修改的文件定位在SDRAM中，不常修改的文件定位在Flash中；同时简化了系统文件的配置和文件属性、访问模式的设置，以便达到系统安全管理的特性。本文所构造的嵌入式Linux文件系统已经在上海维豪信息技术有限公司的电子政务项目的一个可信移动终端设备——安全个人计算中心sPCC中的安全模组里的Linux操作系统中得到了应用，并取得了比较好的效果。更多还原

【Abstract】 File system is one of the most primary sources in operating system, which is a collection of files and directories in a computer system. With the increasing of availability and lowering of price of embedded system hardware, and the expanding of application fields of embedded system, the embedded operating systems play a more important role and the development of embedded file system attract more attention. Due to the difference of system architecture and application requirement, there is a big difference between file system in embedded devices and that in desktop computers, such as: real-time response, transplantation, reducing and configuration, etc.The article describes a specified file system in embedded Linux, which is based on a standard Linux file system structure, and was transplanted to the hardware platform of a handed computing product after proper reducing and configuration.Firstly, the article gave a brief introduction to embedded system, Linux operating system, and their combination-embedded Linux operating system, and described its characters, advantages and the advance in the world; Secondly, the paper described the composition and structure of Linux file system, and gave detailed description about the primary and important files. Thirdly, the paper described the construction of one kind of embedded Linux file system in details, and discussed how to select and configure the needed files, and how to configure the authorities of users and groups to meet security requirement. At last, the paper summarized how to construct a development platform for further development of embedded system on the base of the constructed file system.The constructed file system inherited the tree directory structure in standard Linux file systems, while much reducing has been done according to the practical hardware limitation and the requirement of the final product, only the most fundamental files needed during the booting and running were reserved, even each of them were simplified as small as possible, to ensure the resulted system to be as small as possible. In addition, the physical arrangement of file system was optimized by placing the often modified files in the SDRAM and the less modified files in the Flash. Simplified configuration of system files and proper configuration of file properties and access mode provided security management for embedded system.The constructed embedded Linux file system has been successfully applied in the sPCC (secure Personal Computing Center), which is a trust mobile device produced by Shanghai Wellhope Information and Technology Co. Ltd.更多还原