linux在嵌入式的應(yīng)用外文翻譯

1、<p>　　Linux應(yīng)用于嵌入式系統(tǒng)</p><p>　　UNIX引起了全然不同的情緒：因其能力和靈活性而受到一些人的青睞，但因其復(fù)雜且神秘的命令而受到另一些人的藐視。在計算世界里，UNIX已建立起一個褒義不一的聲譽。</p><p><b>　　易用性</b></p><p>　　UNIX因其過于神秘、不易記憶和含義模糊的大量鍵盤

2、命令而名聲不佳，這些命令每個都有很多命令行開關(guān)，這可能造成昏藥而不易記憶。它的SVR4版本擁有2000多個命令，其中很多功能可通過管道和重定向進行組合。這反映了UNIX的基本設(shè)計思想之一：生成數(shù)量很大的專用和模塊化命令，把它們結(jié)合起來就能完成各種復(fù)雜的任務(wù)。</p><p>　　雖然UNIX過去基本上限于大學和應(yīng)用開發(fā)公司中的軟件專業(yè)人員使用，其復(fù)雜的命令行語法和由此而得到的靈活性被看作一個優(yōu)點而不是問題。但是在

3、面向商業(yè)的市場中使用UNIX，卻產(chǎn)生了一個重大的缺陷——系統(tǒng)越靈活，它就變得越難學會和操作。</p><p>　　UNIX的原本（或腳本）語言提供某種形式的幫助。利用原本語言，系統(tǒng)管理員能很快地把系統(tǒng)裁剪成滿足一組用戶的需求。</p><p>　　克服UNIX神秘命令語言之困難的另一種方法是用圖形用戶接口GUI，如Motif,SunView或OpenLook。然而，圖形用戶接口在已經(jīng)很復(fù)雜

4、的系統(tǒng)上增添了另一層不兼容性問題。</p><p>　　Motif已經(jīng)移植到差別非常大的不同體系結(jié)構(gòu)上（由于它仿效Presentation Manager的風格），而且在外觀與感覺上也許是最接近于諸如Microsoft Windows一類的PC接口。SunView由于有很大的裝機數(shù)和很多應(yīng)用程序員已熟悉按它的規(guī)范寫軟件，所以也是一種主流圖形用戶接口。</p><p><b>　　

5、二進制兼容性</b></p><p>　　UNIX的銷售者以某種羨慕的心情關(guān)注著DOS世界中可能的大量簡裝應(yīng)用程序，并承諾不同系統(tǒng)的二進制兼容的應(yīng)用程序即將面世。這些承諾遠未讓人滿足。雖然二進制兼容性尚未獲得，但現(xiàn)在不同機器上共享數(shù)據(jù)和應(yīng)用程序正在變得更加容易。</p><p><b>　　可移植性</b></p><p>　　與多

6、數(shù)操作系統(tǒng)源碼相比，UNIX程序容易移植。它用C語言編寫，而不用匯編語言，使用UNIX能移植到不同的體系結(jié)構(gòu)上。但是把UNIX移植到一個新系統(tǒng)上也不是一件一蹴而就的事情，常常是要幾個人年的工作，還可能造成故障和失靈，從而在性能上產(chǎn)生難以捉摸的不一致性。這些故障往往是難以識別與糾正的。</p><p>　　擁有你自己的計算機操作系統(tǒng)的源碼，既有益，也有害；如果操作系統(tǒng)缺少某些所需功能，公司自己擁有源碼能大大增強公司

7、進行必要修改的能力。</p><p>　　另一方面，具有新的或修改特性的操作系統(tǒng)定制版本，在日后可能出現(xiàn)與更新的版本或購買的應(yīng)用程序不兼容的問題。 </p><p>　　為什么用LINUX？</p><p>　　用于接口、監(jiān)控、通信和控制應(yīng)用程序的職能專用系統(tǒng)和設(shè)備越來越要求高級的現(xiàn)代操作系統(tǒng)的這些服務(wù)。許多這樣的系統(tǒng)需要如下的高級性能：高分辨率和用戶友好的圖

8、形用戶界面：TCP/IP鏈接；用可靠的閃存固態(tài)盤代替常規(guī)的磁盤機；支持32位的超高速CPU；使用大存儲器陣列； 以及似乎是無限容量的存儲設(shè)備，包括CD-ROM和硬盤。</p><p>　　這不是以前的獨立代碼，自己寫的核，或簡單的老是DOS，那些日子已永遠過去。</p><p>　　另外也考慮到硬件和芯片迅速加速的革新步伐——伴隨著老設(shè)備相當快地淘汰。結(jié)合這兩種情況，就能知道為什么對商用實

9、時操作系統(tǒng)供應(yīng)商而言，跟上硬件設(shè)備的不斷出新已變成巨大的挑戰(zhàn)。及時地支持最新設(shè)備，甚至不去理會不愿退讓的、大力推銷的逐漸過時的芯片組，你需要大量和不斷的資材投入。如果商用實時操作系統(tǒng)供應(yīng)商必須奮力緊跟硬件發(fā)展的話，那么編寫?yīng)毩⒌拇a或?qū)懽约旱暮?，這種單槍匹馬的做法一定是毫無意義的。</p><p>　　因為選擇范圍很小，嵌入式系統(tǒng)的開發(fā)商面臨這樣的一種困境：</p><p>　　一方面，今

10、天高度復(fù)雜的，且授權(quán)的智能嵌入式系統(tǒng)（基于最新的芯片和硬件性能）所需要的正式流行的高檔操作系統(tǒng)（如Windows）提供的那種能力、精致性，以及通用性。</p><p>　　另一方面，嵌入式系統(tǒng)要求非常高的可靠性（不停機，無人照管的操作），加上有能力把操作系統(tǒng)改編成符合應(yīng)用系統(tǒng)的獨特的要求。</p><p>　　其窘境是：通用桌面操作系統(tǒng)（如Windows）不能很好地適應(yīng)于類似設(shè)備的嵌入式系

11、統(tǒng)的獨特需求。然而，商用實時操作系統(tǒng)，雖然設(shè)計成滿足嵌入式應(yīng)用的可靠性和配置靈活性的要求，但由于他們?nèi)狈藴驶约皼]有能力跟上技術(shù)的速度發(fā)展步伐，它們?nèi)找娌缓闲枰?lt;/p><p><b>　　開發(fā)人員做什么？</b></p><p>　　幸運的是，一種新的、令人興奮的選擇系統(tǒng)已經(jīng)出現(xiàn)：開放源碼Linux。Linux提供功能強大的和高級系統(tǒng)管理設(shè)施。豐富的設(shè)備支持，在

12、可靠性和魯棒性，以及廣泛詳盡的文檔方面有極好的聲譽。最好的（對系統(tǒng)開發(fā)人員而言）是Linux不要錢——有完全免費的源代碼。</p><p>　　Linux是不是像Windows那樣太大以及需要系統(tǒng)資源太多，以致不能滿足嵌入式系統(tǒng)的約束要求呢？與Windows不同，Linux本來就是模塊化的，并且能夠很容易縮減成緊縮配置，這種配置幾乎與DOS差不多大，甚至能放到一張軟盤上。此外，因為Linux源碼是免費可用的，所以

13、可以按照獨特的嵌入式系統(tǒng)要求改編該操作系統(tǒng)。</p><p>　　這樣，并不令人驚奇，開放源碼Linux已建成了一個新的操作系統(tǒng)開發(fā)和支持范例，在那里數(shù)以千計的開發(fā)人員繼續(xù)貢獻于不斷發(fā)展的Linux代碼庫。此外，幾十家面向Linux的軟件公司已經(jīng)出現(xiàn)——他們熱切支持那些為建立從工廠自動化到智能設(shè)備范圍很廣的應(yīng)用系統(tǒng)的開發(fā)人員的要求。</p><p><b>　　小Linux<

14、;/b></p><p>　　對許多嵌入式系統(tǒng)，為了適應(yīng)諸如RAM、固態(tài)盤、處理機速度，以及功耗的約束，嵌入的Linux的主要任務(wù)是，使系統(tǒng)所需的資源最小。嵌入式操作系統(tǒng)可能需要從一個芯片盤或緊湊閃存固態(tài)盤上自舉；或者自舉和運行在沒有顯示器和鍵盤（“無頭”操作）的環(huán)境，或經(jīng)有以太網(wǎng)連接，從遠程設(shè)備裝入應(yīng)用程序。</p><p>　　現(xiàn)成的小Linux有許多來源，其中有日益增多的面向應(yīng)

15、用的Linux配置和分發(fā)版，這些都被修改成適應(yīng)于特定的應(yīng)用。例如路由器、防火墻、互聯(lián)網(wǎng)/網(wǎng)絡(luò)設(shè)備、網(wǎng)絡(luò)服務(wù)器、網(wǎng)關(guān)等。</p><p>　　你也可能選擇建立你自己喜歡的嵌入式Linux，從一個標準分發(fā)版開始，略去不要的模塊。雖然如此，還應(yīng)該考慮從別人的工作配置基礎(chǔ)上開始你的工作，因為他們的版本的源僅是完全合法的，而且也是被鼓勵。</p><p><b>　　實時Linux<

16、/b></p><p>　　許多嵌入式系統(tǒng)需要對現(xiàn)實世界的一些事件可預(yù)測，并且受限響應(yīng)。這樣的實時系統(tǒng)包括工廠自動化、數(shù)據(jù)采集和控制系統(tǒng)、音頻/視頻應(yīng)用，以及許多其他計算機化的產(chǎn)品和設(shè)備。什么是“實時系統(tǒng)”？通常接受的“實時”性能的定義是，現(xiàn)實世界時間必須在確定的、可預(yù)測的，以及在相對短的時間間隔內(nèi)得到響應(yīng)。</p><p>　　雖然Linux不是一個實時操作系統(tǒng)（Linux內(nèi)核不提

17、供所需要的事件優(yōu)先級和搶占功能），但當前有幾個擴充選項可用，這些選項把實時能力帶給基于Linux的系統(tǒng)，最通常的方法是雙內(nèi)核方法。用這個方法，通用（非實時）OS運行作為實時內(nèi)核的一個任務(wù)。通用操作系統(tǒng)提供諸如磁盤讀/寫、LAN/通信、串行/并行I/O、系統(tǒng)初始化、內(nèi)存管理等功能，而實時內(nèi)核處理時限世界事件。你可以把這個看作兩者兼得，因為它能夠保持流行的通用操作系統(tǒng)好處，而增加了實時OS的能力。就Linux來說，你能保持與標準Linux兼

18、容，而以非干擾的方式增加了實時功能。</p><p>　　當然，也可以專研并修改Linux，把改變成實時操作系統(tǒng)，因為它的源碼是公開可用的，但如果這樣做，你會面臨這樣嚴重缺點，即不論特性方面，還是驅(qū)動程序方面都不能與主流Linux同步前進。簡言之，你的制定Linux將不能從Linux的不斷進展中獲得好處，而這種進展是世界范圍內(nèi)數(shù)以千計的開發(fā)人員共同協(xié)力的結(jié)果。</p><p>　　Linu

19、x是一個操作系統(tǒng)，它擔當計算機系統(tǒng)硬件與軟件間的通信服務(wù)，Linux內(nèi)核包含了你在任何操作系統(tǒng)所期望的所有特性。</p><p><b>　　原文：</b></p><p>　　Using Linux in Embedded Systems</p><p>　　UNIX evokes a wide range of emotions: love

20、d by some for its power and flexibility, despised by others for its eomplex and arcane commands. UNIX has established a checkered reputation in the world of computing.</p><p>　　EASE OF USE</p><p&g

21、t;　　UNIX is infamous for its glut of arcane , non-mnemonic, and cryptic keyboard commands, each with many command-line switches, which can be incredibly confusing to remember. Its SVR 4 implementation contains more than

22、2,000 comands. Many of these functions can be combined, using pipes and redirection. This illustrates one of UNIX’s design fundamentals: the creation of a large assortment of very specialized and modular commands that ca

23、n be combined to accomplish complex tasks.</p><p>　　While UNIX was essentially limited to use by software professionals at universities and in applications development houses, its complex command-line syntax

24、 and resulting flexibility were considered an advantage rather than a problem.But this same flexibility also creates a major drawback for using UNIX in a business-oriented market—the more flexible a system is, the more d

25、ifficult it becomes to learn and operate.</p><p>　　UNIX’s script languages provide one form of help. Using scripts, a system administrator can tailor the system to a set of users’ needs quickly.</p>&

26、lt;p>　　Another factor mitigating the difficulties of UNIX’s arcane command language are the Graphic User Interfaces(GUIs), such as Motif, SunView, or OpenLook. GUIs, however, place another level of incompatibility pro

27、blems on what is already a complex system.</p><p>　　Motif has been ported to the most different architectures and (because it follows the Presentation Manager style ) is perhaps closest in look and feel to a

28、 PC interface such as Microsoft Windows. Sun View is also dominant because of its large installed base and the numbers of applications programmers who have become familiar with writing software to its specifications.<

29、/p><p>　　BINARY COMPATIBILITY</p><p>　　UNIX marketers have looked with some envy at the huge-base of shrink-wrapped applications available in the DOS world and have promised that binary-compatible

30、applications for systems is just around the corner. These promises have yet to be met in any significant way. While binary compatibility is not yet available, it is getting easier to share data and applications across di

31、fferent machines.</p><p>　　PORTABILITY </p><p>　　Compared with most operating system sources, UNIX code is quite move UNIX to different architectures. But a UNIX port to a new system is not a tr

32、ivial matter, offen taking several man-years of work, and can result in glitches and malfunctions, which may create very subtle inconsistencies in performance. These bugs are often difficult to identify and correct.</

33、p><p>　　Having the source code available for your computer’s operating system is beneficial and detrimental: if the OS lacks certain desirable featuers, having the sources in-house greatly enhances a company’s

34、ability to make necessary changes.</p><p>　　On the other hand, the customized version of the operating system, with its new or modified features may later present compatibility problems with newer releases o

35、r purchased application.</p><p>　　Why Linux?</p><p>　　Intelligent dedicated systems and applicances used in interface, monitoring , communications, and control applications increasingly demand t

36、he services of a sophisticated, state-of-the-art operating systems. Many such systems require advanced capabilities like: high resolution and user-friendly graphical user interfaces(GUIs); TCP/IP connectivity; substituti

37、on of reliable( and low power)flash memory solid state disk for conventional disk drives; support for 32-bit ultra-high-speed CPUs; the use </p><p>　　This is not the stuff of yesteryear’s “standalone” code,

38、“roll-your-own” kernels, or “plain old DOS”, No, those days are gone—forever.</p><p>　　Then too, consider the rapidly accelerating pace of hardware and chipset innovation—accompanied by extremely rapid obsol

39、escence of the older devices.Combine these two, and you can see why it’s become an enormous challenge for commercial RTOS vendors to keep up with the constant churning of hardware devices . Supporting the newest devices

40、in a timely manner—even just to stay clear of the unrelenting steamroller of chipset obsolescence–takes a large and constant resource commitment. If it’s a stru</p><p>　　With the options narrowing, embedded

41、system developers find themselves faced with a dilemma:</p><p>　　On the one hand, today’s highly sophisticated and empowered intelligent embedded systems—based on the newest chips and hardware capabilities—d

42、emand noting less than the power, sophistication, and currency of support provided by a popular high-end operating system like windows.</p><p>　　On the other hand, embedded systems demand extremely high reli

43、ability(for non-stop, unattended operation)plus the ability to customize the OS to match an application’s unique requirements.</p><p>　　The dilemma is: common desktop operating system ( such as Windows ) are

44、 not well adapted to the similar equipment to the unique needs of embedded system. However, commercial real-time operating system, although designed to meet the embedded application reliability and configuration flexibil

45、ity requirements, but due to their lack of standardization and inability to keep up with the speed of technology development, which is undesirable.</p><p>　　Developers do?</p><p>　　Fortunately,

46、a new, exciting alternative systems have emerged: the open source Linux. Linux provides powerful and advanced system management facilities. A wealth of equipment support, the reliability and robustness, and extensive doc

47、umentation has an excellent reputation. The best ( for developers ) is Linux not money -- are completely free source code.</p><p>　　Linux is it right? Like Windows is too large and the need for system resour

48、ces too much, so can not meet the requirements of embedded system? Unlike Windows, Linux is a modular, and can easily be reduced into compact configuration, this configuration is almost almost DOS, even on a single flopp

49、y disk. In addition, because the Linux source code is freely available, so it can be in accordance with the unique requirements of embedded systems to adapt the operating system.</p><p>　　So, not surprisingl

50、y, the open source Linux has built a new operating system development and support the paradigm, where thousands of developers continue to contribute to the development of the Linux code library. In addition, dozens of Li

51、nux oriented software companies have emerged -- they eager to support those built from factory automation to intelligent devices are a wide range of application systems development personnel requirements.</p><

52、p>　　Small Linux</p><p>　　For many embedded systems, such as RAM, in order to adapt to the solid state disk, processor speed, and power constraint, embedded Linux is a major task, the system resources req

53、uired minimum. Embedded operating system may need from a chip disk or compact flash solid state disk bootstrap; or bootstrap and operation in the absence of the display and the keyboard (" headless" operation )

54、 environment, or by the Ethernet connection, from a remote device in application.</p><p>　　Small ready-made Linux has many sources, including the increasing application oriented Linux configuration and distr

55、ibution, these are modified into adapted to specific application. For example, router, firewall, Internet / network equipment, network server, gateway.</p><p>　　You may also choose to build your own like emb

56、edded Linux, from a standard distribution version, omitting don't module. Even so, also should be taken from the work of others on the basis of the allocation to begin your work, because their version of the source i

57、s perfectly legal, but also be encouraged.</p><p>　　Real time Linux</p><p>　　Many embedded systems need to real-world events can be predicted, and limited response. Such a system include factory

58、 automation, data acquisition and control system, audio / video applications, as well as many other computer products and equipment. What is" real time system"? The generally accepted" real-time" perf

59、ormance is defined, the real world time must be identified, predictable, and within a relatively short time interval in response.</p><p>　　Although Linux is not a real-time operating system ( Linux core

60、s do not provide the required priority and preemption features ), but currently a few expansion options available, these options to bring real-time ability based on Linux system, the most common method is the double kern

61、el method. Using this method, the general ( real time) OS running as a real-time kernel of a task. General purpose operating system such as disk read / write, LAN / communication, serial / parallel I / O, system initi<

62、;/p><p>　　Of course, also can inquiry and modify Linux, change into a real-time operating system, because it is the source of publicly available, but if you do, you will face such serious shortcomings, namely w

63、hether characteristics, or the driver can not synchronize with the mainstream Linux. Jane's words, you will not make Linux from Linux development benefit, but this progress is within the scope of the world thousands

64、of developers to collaborate on results.</p><p>　　Linux is an operating system, it play of computer system hardware and software communication service, the Linux kernel contains the operating system you in a