基于ARM9的Android终端系统的研究与实现

发布时间：2019-03-23 15:02

【摘要】：随着信息技术的不断发展和移动互联网时代的到来,越来越多的移动终端设备开始走进人们的日常生活,新的终端产品层出不穷,展示了其巨大的市场前景。伴随着移动终端设备的智能化、多功能化,嵌入式操作系统在移动终端设备中起着举足轻重的作用,寻找一款稳定、开放的嵌入式终端系统,成为各大终端设备开发商的当务之急。Android操作系统以Google公司为后盾,博众取长,以其友好的人机交互界面和开源等优点成为各大厂商的首选。Android是Google公司专门为移动终端设备定制的OS平台,以其可定制性、稳定性适应不同的硬件平台,在短短几年内占领绝大部分终端市场。Android要继续扩大市场,必将向低功耗、高性能、低成本的方向发展。本文针对Android的发展趋势,提出了将Android终端系统移植到ARM9平台的课题,预计建立一个稳定的平台并提供一个可用的移植方案,应用到Android终端设备的低端市场。本文所做主要工作包括：采用uboot作为Android终端系统的引导加载程序,分析了uboot的启动流程,对uboot进行了移植,并在原有功能的基础上添加usb、nand flash、yaffs2和双启动相关的模块代码增加优良的功能以极大程度地满足开发和系统的需求。本文改进后的uboot在文件系统镜像加载速度、镜像烧写速度以及用户界面友好性等方面比开源的uboot有很大的改善。分析目标板硬件与Android运行所需基本硬件、Android内核与linux内核的不同,根据既有移植方案的缺陷,采用向Android内核中移植2440目标板的板级支持包的方案,根据既有硬件资源对Android内核源码进行修整使其适应目标机。这种方案比既有方案代码改动量少,出错率低。采用2.6版本内核提供的系统模型来设计目标板的外围设备驱动程序,充分利用系统模型的优越性。驱动程序的设计过程中,内核比较完善的驱动参考已有的代码进行移植,系统未实现的驱动以及版本比较老的驱动根据系统模型进行重新设计。该方案比传统的驱动程序设计方法节省工作量的同时也提高了与系统紧密结合度。分析目标机和Android2.1所支持的指令架构,采用对原生的Android文件系统进行指令降级的方式来兼容目标板的体系结构,并针对目标板平台对文件系统进行修改,在将Android文件系统移植到目标板平台的过程上达到了技术上的创新。经过一系列的整合测试以及系统优化,本文所实现的终端系统软硬件性能良好、运行稳定,从而验证了系统可以应用到终端设备低端市场的可行性。
[Abstract]:With the continuous development of information technology and the arrival of mobile Internet era, more and more mobile terminal devices begin to enter people's daily life, new terminal products emerge in endlessly, showing its huge market prospect. Along with the intelligence and multi-function of mobile terminal device, embedded operating system plays an important role in mobile terminal device, looking for a stable and open embedded terminal system. Google operating system is backed by the company Google, and the public will take the length of the operating system as the backing of the major end device developers. Because of its friendly man-machine interface and open source, it has become the first choice of the major manufacturers. Google is a OS platform specially designed for mobile terminal devices, which can be customized and adapted to different hardware platforms with its customizability and stability. Android will continue to expand the market, it will develop to low power consumption, high performance and low cost. In view of the development trend of Android, this paper puts forward the issue of porting Android terminal system to ARM9 platform. It is expected to establish a stable platform and provide an available migration scheme, which can be applied to the low-end market of Android terminal equipment. The main work of this paper includes: using uboot as the boot loader of Android terminal system, analyzing the start-up flow of uboot, porting the uboot, and adding usb,nand flash, on the basis of the original function. Yaffs2 and dual boot-related module code add excellent functionality to meet the development and system needs to a great extent. The improved uboot is much better than the open source uboot in the file system image loading speed, image burning speed and user interface friendliness. This paper analyzes the difference between the target board hardware and the basic hardware required by the Android operation, and the difference between the Android kernel and the linux kernel. According to the defects of the existing migration schemes, the board-level support package of the 2440 target board is transplanted to the Android kernel. According to the existing hardware resources, the Android kernel source code is trimmed to adapt to the target machine. This scheme has less improvement and lower error rate than the existing scheme code. The system model provided by version 2.6 kernel is used to design the peripheral device driver of the target board, which makes full use of the superiority of the system model. In the process of driver design, the kernel driver is transplanted according to the existing code, the unrealized driver and the older driver are re-designed according to the system model. Compared with the traditional driver design method, this scheme can save work and improve the degree of close integration with the system at the same time. The instruction architecture supported by the target machine and Android2.1 is analyzed, and the native Android file system is demoted to be compatible with the system structure of the target board, and the file system is modified according to the target board platform. In the process of porting the Android file system to the target board platform, the technical innovation has been achieved. After a series of integration tests and system optimization, the hardware and software performance of the terminal system in this paper is good and the operation is stable, which verifies the feasibility of the system being applied to the low-end market of the terminal equipment.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP368.1;TP316

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