發(fā)布時(shí)間：2018-02-03 10:12

  本文關(guān)鍵詞： 嵌入式 文件系統(tǒng) NAND Flash Cache FAT　出處：《北京交通大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

【摘要】：處理器技術(shù)、存儲器技術(shù)和軟件技術(shù)的飛速發(fā)展,極大地改變了人們的生活狀態(tài),讓生活變得更智能,更隨心所欲。而嵌入式系統(tǒng)正是集成了這三種技術(shù)的產(chǎn)物,加強(qiáng)對嵌入式技術(shù)的研究,必將有助于該產(chǎn)業(yè)的健康發(fā)展,并會(huì)給人們生活帶來巨大的便利。 嵌入式系統(tǒng)包括硬件平臺、EOS和嵌入式應(yīng)用軟件。其中硬件平臺主要是指嵌入式處理器和存儲器,EOS有Linux、Wince、Vworks等,嵌入式應(yīng)用軟件更是種類繁多,不可計(jì)數(shù)。嵌入式文件系統(tǒng),是EOS中非常重要的組成部分,它主要負(fù)責(zé)數(shù)據(jù)在存儲器上的存放、操作和管理,并向用戶提供底層的操作接口,使用戶不必深入了解底層結(jié)構(gòu),就能方便操作。嵌入式文件系統(tǒng)與一般的磁盤文件系統(tǒng)結(jié)構(gòu)大致相同,但其有自己的特點(diǎn)。首先,嵌入式設(shè)備受系統(tǒng)資源的限制較大,所以嵌入式文件系統(tǒng)必須處理好空間與效率的關(guān)系；其次,嵌入式系統(tǒng)一般要求實(shí)時(shí)性和可靠性,這也是非常重要的；再次,嵌入式文件系統(tǒng)采用的存儲器一般是NAND Flash,而NAND Flash由于自身的特點(diǎn),需要在其和FAT層之間引入FTL層,才能進(jìn)行類似與磁盤的操作。FTL的主要功能是進(jìn)行邏輯地址和物理地址間的轉(zhuǎn)換和壞塊管理。 本文在介紹相關(guān)處理器和存儲器知識的基礎(chǔ)上,為TEE(可信執(zhí)行環(huán)境)系統(tǒng),設(shè)計(jì)了一套專用的文件系統(tǒng),無需考慮與其他系統(tǒng)的兼容性。TEE系統(tǒng)是握奇數(shù)據(jù)有限公司為手機(jī)支付開發(fā)的一套安全操作系統(tǒng),其運(yùn)行在Android系統(tǒng)上,當(dāng)需要用手機(jī)進(jìn)行支付時(shí)進(jìn)入該安全環(huán)境,本課題是其中一個(gè)重要模塊。在借鑒FAT32的設(shè)計(jì)思路和關(guān)鍵技術(shù)后,我們設(shè)計(jì)了一種精簡的類FAT文件系統(tǒng)。在文件系統(tǒng)格式上,我們用系統(tǒng)信息區(qū)取代了系統(tǒng)引導(dǎo)區(qū),省去了不常用的備用FAT表,僅保留一張F(tuán)AT表。在功能實(shí)現(xiàn)上,也考慮了嵌入式設(shè)備資源有限的特點(diǎn)。為了對文件中數(shù)據(jù)進(jìn)行更快、更安全的存取,我們在文件系統(tǒng)的FTL層和FAT層之間引入了Cache層。它是FTL進(jìn)行直接讀寫的唯一通道,用于提高系統(tǒng)性能以及使系統(tǒng)可以按字節(jié)讀寫某個(gè)特定扇區(qū),并對其讀寫操作進(jìn)行了實(shí)現(xiàn)和優(yōu)化。我們進(jìn)一步討論了Cache性能與命中率的關(guān)系,以及影響Cache命中率的因素。
[Abstract]:The rapid development of processor technology, memory technology and software technology has greatly changed people's living conditions and made life more intelligent. The embedded system is the product of the integration of these three technologies. Strengthening the research of embedded technology will help the healthy development of the industry and bring great convenience to people's life. The embedded system includes the hardware platform EOS and embedded application software, in which the hardware platform mainly refers to the embedded processor and memory EOS, such as Linux WinceVworks and so on. Embedded file system is a very important part of EOS, it is mainly responsible for the storage, operation and management of data in memory. And to provide users with the underlying operation interface, so that users do not need to understand the underlying structure, can be convenient to operate. Embedded file system and the general disk file system structure is roughly the same. But it has its own characteristics. Firstly, the embedded device is limited by the system resources, so the embedded file system must deal with the relationship between space and efficiency. Secondly, embedded systems generally require real-time and reliability, which is also very important; Thirdly, the memory used in embedded file system is generally NAND Flash, but NAND Flash needs to introduce FTL layer between FAT layer and NAND Flash because of its own characteristics. The main function of FTL is to translate logical address and physical address and bad block management. Based on the introduction of related processors and memory knowledge, this paper designs a special file system for TEE (trusted execution Environment) system. No need to consider compatibility with other systems. Tee system is a secure operating system for mobile phone payment developed by Juggi data Co., Ltd., which runs on the Android system. This topic is one of the important modules when the payment needs to be paid by mobile phone. After learning from the design ideas and key technologies of FAT32. We design a simplified FAT like file system. In the file system format, we use the system information area instead of the system boot area, eliminating the uncommon standby FAT table. Only one FAT table is retained. In the implementation of the function, the limited resources of embedded devices are also taken into account. In order to access the data in the file faster and more safely. We introduced the Cache layer between the FTL layer and the FAT layer of the file system, which is the only channel for FTL to read and write directly. It is used to improve system performance and enable the system to read and write a particular sector by bytes, and to implement and optimize the read and write operation. We further discuss the relationship between Cache performance and hit rate. And the factors that affect the Cache hit ratio.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TP333;TP316

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本文編號：1487112