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&nbsp;容&nbsp;易&nbsp;造&nbsp;成&nbsp;其&nbsp;他&nbsp;问&nbsp;题。&nbsp;更&nbsp;主&nbsp;要&nbsp;的&nbsp;是&nbsp;这&nbsp;保&nbsp;留&nbsp;了&nbsp;这&nbsp;部&nbsp;分&nbsp;功&nbsp;能，&nbsp;能&nbsp;够&nbsp;<br />
&nbsp;使&nbsp;得&nbsp;不&nbsp;同&nbsp;进&nbsp;程&nbsp;使&nbsp;用&nbsp;相&nbsp;同&nbsp;代&nbsp;码&nbsp;。&nbsp;如&nbsp;果&nbsp;没&nbsp;有&nbsp;了&nbsp;这&nbsp;个&nbsp;功&nbsp;能，&nbsp;每&nbsp;个&nbsp;程&nbsp;<br />
&nbsp;序&nbsp;都&nbsp;需&nbsp;要&nbsp;自&nbsp;己&nbsp;的&nbsp;运&nbsp;行&nbsp;库，&nbsp;在&nbsp;内&nbsp;存&nbsp;中&nbsp;就&nbsp;会&nbsp;有&nbsp;库&nbsp;的&nbsp;很&nbsp;多&nbsp;拷&nbsp;贝。&nbsp;其&nbsp;<br />
&nbsp;实&nbsp;只&nbsp;需&nbsp;把&nbsp;交&nbsp;换&nbsp;空&nbsp;间&nbsp;的&nbsp;长&nbsp;度&nbsp;设&nbsp;置&nbsp;为&nbsp;零，&nbsp;就&nbsp;可&nbsp;以&nbsp;关&nbsp;闭&nbsp;虚&nbsp;拟&nbsp;内&nbsp;存&nbsp;的&nbsp;<br />
&nbsp;页&nbsp;面&nbsp;换&nbsp;入&nbsp;和&nbsp;换&nbsp;出&nbsp;功&nbsp;能。&nbsp;对&nbsp;一&nbsp;些CPU，&nbsp;虚&nbsp;拟&nbsp;存&nbsp;储&nbsp;器&nbsp;的&nbsp;功&nbsp;能&nbsp;提&nbsp;供&nbsp;内&nbsp;<br />
&nbsp;存&nbsp;管&nbsp;理，&nbsp;防&nbsp;止&nbsp;不&nbsp;同&nbsp;程&nbsp;序&nbsp;占&nbsp;用&nbsp;相&nbsp;同&nbsp;的&nbsp;地&nbsp;址&nbsp;空&nbsp;间。&nbsp;而&nbsp;在&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;<br />
&nbsp;统&nbsp;中，&nbsp;使&nbsp;用&nbsp;简&nbsp;单&nbsp;、&nbsp;绝&nbsp;对&nbsp;的&nbsp;地&nbsp;址&nbsp;空&nbsp;间，&nbsp;因&nbsp;此&nbsp;这&nbsp;种&nbsp;功&nbsp;能&nbsp;也&nbsp;不&nbsp;会&nbsp;起&nbsp;<br />
&nbsp;作&nbsp;用。&nbsp;不&nbsp;过&nbsp;这&nbsp;到&nbsp;提&nbsp;供&nbsp;了&nbsp;防&nbsp;止&nbsp;误&nbsp;写&nbsp;以&nbsp;至&nbsp;于&nbsp;使&nbsp;系&nbsp;统&nbsp;崩&nbsp;溃&nbsp;的&nbsp;功&nbsp;能。&nbsp;<br />
&nbsp;很&nbsp;多&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;习&nbsp;惯&nbsp;使&nbsp;用“&nbsp;全&nbsp;局&nbsp;变&nbsp;量”，&nbsp;让&nbsp;进&nbsp;程&nbsp;共&nbsp;享&nbsp;数&nbsp;据&nbsp;。&nbsp;&nbsp;<br />
在Linux&nbsp;系&nbsp;统&nbsp;中&nbsp;提&nbsp;供&nbsp;共&nbsp;享&nbsp;内&nbsp;存&nbsp;方&nbsp;法&nbsp;让&nbsp;进&nbsp;程&nbsp;共&nbsp;享&nbsp;数&nbsp;据&nbsp;信&nbsp;息。&nbsp;在RT－&nbsp;<br />
Linux&nbsp;中&nbsp;使&nbsp;用FIFO&nbsp;进&nbsp;行&nbsp;信&nbsp;息&nbsp;交&nbsp;换。&nbsp;<br />
7．&nbsp;处&nbsp;理&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;很&nbsp;多&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;没&nbsp;有磁&nbsp;盘&nbsp;和文&nbsp;件&nbsp;系&nbsp;统；Linux&nbsp;也&nbsp;<br />
&nbsp;可&nbsp;以&nbsp;在没&nbsp;有&nbsp;磁&nbsp;盘&nbsp;的&nbsp;系&nbsp;统&nbsp;上&nbsp;运&nbsp;行。&nbsp;正&nbsp;如&nbsp;上&nbsp;面&nbsp;提&nbsp;到&nbsp;的，&nbsp;应&nbsp;用&nbsp;程&nbsp;序&nbsp;&nbsp;<br />
可&nbsp;以&nbsp;和&nbsp;核&nbsp;心&nbsp;一&nbsp;起&nbsp;编&nbsp;译，&nbsp;在&nbsp;启&nbsp;动&nbsp;时&nbsp;一&nbsp;起&nbsp;装&nbsp;入&nbsp;运&nbsp;行。&nbsp;这&nbsp;适&nbsp;应&nbsp;于&nbsp;简&nbsp;&nbsp;<br />
单&nbsp;系&nbsp;统，&nbsp;但不&nbsp;具&nbsp;有&nbsp;灵&nbsp;活&nbsp;性。&nbsp;其&nbsp;实，&nbsp;许&nbsp;多&nbsp;商&nbsp;业&nbsp;的&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;都&nbsp;提&nbsp;<br />
&nbsp;供&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;的&nbsp;选&nbsp;择。&nbsp;大&nbsp;都&nbsp;是&nbsp;特&nbsp;殊&nbsp;的&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;或&nbsp;者&nbsp;兼&nbsp;容MS－DOS&nbsp;&nbsp;<br />
文&nbsp;件&nbsp;系&nbsp;统。Linux&nbsp;提&nbsp;供&nbsp;包&nbsp;括MS－DOS&nbsp;等许&nbsp;多&nbsp;选&nbsp;择。&nbsp;其&nbsp;他&nbsp;的&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;具&nbsp;<br />
&nbsp;有&nbsp;更&nbsp;好&nbsp;的&nbsp;性&nbsp;能。Linux&nbsp;还&nbsp;具&nbsp;有&nbsp;许&nbsp;多&nbsp;实&nbsp;时商&nbsp;业&nbsp;操&nbsp;作&nbsp;系&nbsp;统&nbsp;所&nbsp;不&nbsp;具&nbsp;备&nbsp;&nbsp;<br />
的检&nbsp;查&nbsp;和&nbsp;修&nbsp;复&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;的&nbsp;功&nbsp;能。&nbsp;这&nbsp;种&nbsp;功&nbsp;能&nbsp;对&nbsp;于&nbsp;通&nbsp;过&nbsp;网&nbsp;络&nbsp;更&nbsp;新&nbsp;&nbsp;<br />
的&nbsp;系&nbsp;统&nbsp;尤&nbsp;为&nbsp;重&nbsp;要。&nbsp;Linux&nbsp;的&nbsp;文&nbsp;件&nbsp;系&nbsp;统&nbsp;可&nbsp;以&nbsp;建&nbsp;立&nbsp;在&nbsp;传&nbsp;统&nbsp;的&nbsp;磁&nbsp;盘&nbsp;上&nbsp;<br />
、Flash&nbsp;Memory、&nbsp;或&nbsp;其&nbsp;他&nbsp;载&nbsp;体。&nbsp;甚&nbsp;至&nbsp;可&nbsp;以&nbsp;用&nbsp;RAM&nbsp;磁&nbsp;盘&nbsp;存&nbsp;放&nbsp;临&nbsp;时&nbsp;文&nbsp;件&nbsp;<br />
。&nbsp;有&nbsp;些&nbsp;系&nbsp;统&nbsp;中&nbsp;包&nbsp;含&nbsp;了&nbsp;廉&nbsp;价&nbsp;的CD－ROM，&nbsp;它&nbsp;比Flash&nbsp;Memory&nbsp;更&nbsp;便&nbsp;宜，&nbsp;更&nbsp;<br />
&nbsp;新&nbsp;升&nbsp;级&nbsp;更&nbsp;容&nbsp;易。Linux&nbsp;系&nbsp;统&nbsp;可&nbsp;以&nbsp;从CD-ROM&nbsp;中&nbsp;启&nbsp;动&nbsp;以&nbsp;及&nbsp;运&nbsp;行&nbsp;程&nbsp;序。&nbsp;&nbsp;<br />
在&nbsp;网&nbsp;络&nbsp;化&nbsp;的&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;，Linux&nbsp;支&nbsp;持NFS（&nbsp;网&nbsp;络&nbsp;文&nbsp;件&nbsp;系&nbsp;统）。&nbsp;于&nbsp;是&nbsp;<br />
&nbsp;，&nbsp;你&nbsp;可&nbsp;以&nbsp;使&nbsp;用&nbsp;很&nbsp;多&nbsp;网&nbsp;络&nbsp;功&nbsp;能。&nbsp;首&nbsp;先，&nbsp;可&nbsp;以&nbsp;通&nbsp;过&nbsp;网&nbsp;络&nbsp;来&nbsp;启&nbsp;动&nbsp;应&nbsp;<br />
&nbsp;用&nbsp;程&nbsp;序。&nbsp;因&nbsp;为&nbsp;通&nbsp;过&nbsp;服&nbsp;务&nbsp;器&nbsp;来&nbsp;启&nbsp;动&nbsp;应&nbsp;用&nbsp;程&nbsp;序，&nbsp;所&nbsp;以&nbsp;是&nbsp;进&nbsp;行&nbsp;软&nbsp;件&nbsp;<br />
&nbsp;更&nbsp;新&nbsp;的&nbsp;最&nbsp;好&nbsp;解&nbsp;决&nbsp;办&nbsp;法。&nbsp;其&nbsp;次，&nbsp;在&nbsp;运&nbsp;行&nbsp;过&nbsp;程&nbsp;中，&nbsp;可&nbsp;以&nbsp;很&nbsp;方&nbsp;便&nbsp;地&nbsp;&nbsp;<br />
导&nbsp;入&nbsp;和&nbsp;导&nbsp;出&nbsp;数&nbsp;据、&nbsp;状&nbsp;态&nbsp;设&nbsp;置&nbsp;和&nbsp;状&nbsp;态&nbsp;信&nbsp;息&nbsp;等。&nbsp;这&nbsp;个&nbsp;功&nbsp;能&nbsp;很&nbsp;适&nbsp;合&nbsp;&nbsp;<br />
用&nbsp;于&nbsp;远&nbsp;程&nbsp;监&nbsp;视&nbsp;和&nbsp;控&nbsp;制&nbsp;应&nbsp;用&nbsp;系&nbsp;统。&nbsp;例&nbsp;如，&nbsp;在RAM&nbsp;中&nbsp;建&nbsp;立&nbsp;磁&nbsp;盘，&nbsp;保&nbsp;存&nbsp;<br />
&nbsp;各&nbsp;种&nbsp;需&nbsp;要&nbsp;的&nbsp;重&nbsp;要&nbsp;数&nbsp;据，&nbsp;远&nbsp;程&nbsp;系&nbsp;统&nbsp;登&nbsp;录&nbsp;到&nbsp;此RAM&nbsp;文&nbsp;件&nbsp;系&nbsp;统，&nbsp;读&nbsp;取&nbsp;<br />
&nbsp;数&nbsp;据，&nbsp;然&nbsp;后&nbsp;在&nbsp;操&nbsp;作&nbsp;者&nbsp;的&nbsp;机&nbsp;器&nbsp;上&nbsp;用&nbsp;图&nbsp;形&nbsp;界&nbsp;面显&nbsp;示&nbsp;运&nbsp;行状&nbsp;态，&nbsp;起&nbsp;到&nbsp;<br />
&nbsp;很&nbsp;好&nbsp;的&nbsp;监&nbsp;视&nbsp;效&nbsp;果。&nbsp;<br />
8．&nbsp;设&nbsp;置&nbsp;启&nbsp;动－LILO&nbsp;和BIOS&nbsp;当&nbsp;微&nbsp;机&nbsp;启&nbsp;动&nbsp;时，&nbsp;它&nbsp;运&nbsp;行&nbsp;预&nbsp;定&nbsp;地&nbsp;址&nbsp;的&nbsp;代&nbsp;&nbsp;<br />
码&nbsp;，那&nbsp;地&nbsp;址通&nbsp;常&nbsp;是&nbsp;在&nbsp;只&nbsp;读&nbsp;存&nbsp;储&nbsp;区，&nbsp;存&nbsp;放&nbsp;有&nbsp;启&nbsp;动&nbsp;代&nbsp;码&nbsp;。&nbsp;在PC&nbsp;中&nbsp;，&nbsp;<br />
&nbsp;即&nbsp;BIOS，&nbsp;它&nbsp;执&nbsp;行&nbsp;底&nbsp;层&nbsp;的CPU&nbsp;初&nbsp;始&nbsp;化&nbsp;工&nbsp;作&nbsp;和&nbsp;初&nbsp;始&nbsp;化&nbsp;设&nbsp;置&nbsp;其&nbsp;他&nbsp;硬&nbsp;件&nbsp;<br />
。BIOS&nbsp;确&nbsp;认&nbsp;哪&nbsp;个&nbsp;硬&nbsp;盘&nbsp;存&nbsp;放&nbsp;操&nbsp;作&nbsp;系&nbsp;统，&nbsp;拷&nbsp;贝&nbsp;操&nbsp;作&nbsp;系&nbsp;统&nbsp;到RAM&nbsp;中，&nbsp;然&nbsp;<br />
&nbsp;后&nbsp;运&nbsp;行&nbsp;操&nbsp;作&nbsp;系&nbsp;统。同&nbsp;样，Linux&nbsp;在PC&nbsp;上&nbsp;运&nbsp;行，&nbsp;依&nbsp;靠PC&nbsp;的BIOS&nbsp;来&nbsp;设&nbsp;置&nbsp;&nbsp;<br />
硬&nbsp;件、&nbsp;启&nbsp;动OS。&nbsp;在&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;中，&nbsp;通&nbsp;常&nbsp;没&nbsp;有BIOS，&nbsp;因&nbsp;此，&nbsp;需&nbsp;要&nbsp;提&nbsp;&nbsp;<br />
供&nbsp;等&nbsp;价&nbsp;的&nbsp;启&nbsp;动&nbsp;代&nbsp;码。&nbsp;嵌&nbsp;入&nbsp;式&nbsp;系&nbsp;统&nbsp;并&nbsp;不&nbsp;需&nbsp;要&nbsp;象PC&nbsp;那&nbsp;样&nbsp;灵&nbsp;活&nbsp;的BIOS&nbsp;<br />
&nbsp;启&nbsp;动&nbsp;程&nbsp;序，&nbsp;它&nbsp;初&nbsp;始&nbsp;化&nbsp;的&nbsp;硬&nbsp;件&nbsp;比&nbsp;较&nbsp;单&nbsp;一。&nbsp;这&nbsp;段&nbsp;代&nbsp;码&nbsp;其&nbsp;实&nbsp;很&nbsp;简&nbsp;单&nbsp;<br />
，&nbsp;只&nbsp;是&nbsp;把&nbsp;一&nbsp;些&nbsp;很&nbsp;重&nbsp;要，&nbsp;而&nbsp;且&nbsp;还&nbsp;要&nbsp;特&nbsp;殊&nbsp;的&nbsp;写&nbsp;入&nbsp;顺&nbsp;序&nbsp;要&nbsp;求&nbsp;的&nbsp;数&nbsp;据&nbsp;<br />
&nbsp;写&nbsp;入&nbsp;硬&nbsp;件&nbsp;的&nbsp;寄&nbsp;存&nbsp;器&nbsp;。&nbsp;另&nbsp;外&nbsp;必&nbsp;须&nbsp;具&nbsp;备&nbsp;的&nbsp;功&nbsp;能&nbsp;有&nbsp;内&nbsp;存&nbsp;检&nbsp;测，&nbsp;点&nbsp;亮&nbsp;<br />
LED，&nbsp;检&nbsp;测&nbsp;其&nbsp;他&nbsp;很&nbsp;重&nbsp;要&nbsp;的&nbsp;硬&nbsp;件。&nbsp;这&nbsp;些&nbsp;代&nbsp;码&nbsp;的&nbsp;针&nbsp;对&nbsp;性&nbsp;很&nbsp;强，&nbsp;不&nbsp;需&nbsp;&nbsp;<br />
要&nbsp;很&nbsp;好&nbsp;的&nbsp;移&nbsp;植&nbsp;性。&nbsp;所&nbsp;以&nbsp;不&nbsp;同&nbsp;的&nbsp;硬&nbsp;件&nbsp;环&nbsp;境&nbsp;需&nbsp;要&nbsp;不&nbsp;同&nbsp;的&nbsp;启&nbsp;动&nbsp;代&nbsp;码&nbsp;<br />
。&nbsp;为&nbsp;了&nbsp;进&nbsp;行&nbsp;测&nbsp;试，&nbsp;可&nbsp;以&nbsp;使&nbsp;用ICE（&nbsp;在&nbsp;线&nbsp;仿&nbsp;真&nbsp;器）&nbsp;或&nbsp;其&nbsp;他&nbsp;的&nbsp;设&nbsp;备&nbsp;来&nbsp;<br />
&nbsp;调&nbsp;试&nbsp;这&nbsp;部&nbsp;分&nbsp;代&nbsp;码&nbsp;。&nbsp;这&nbsp;部&nbsp;分&nbsp;代&nbsp;码&nbsp;总&nbsp;是&nbsp;运&nbsp;行&nbsp;在Flash&nbsp;或EPROM&nbsp;等&nbsp;芯&nbsp;片&nbsp;<br />
&nbsp;上，&nbsp;所&nbsp;以，&nbsp;需&nbsp;要&nbsp;把&nbsp;它&nbsp;们&nbsp;写&nbsp;入&nbsp;这&nbsp;些&nbsp;芯&nbsp;片。&nbsp;如&nbsp;何&nbsp;写，&nbsp;当&nbsp;然&nbsp;因&nbsp;硬&nbsp;件&nbsp;的&nbsp;<br />
&nbsp;不&nbsp;同&nbsp;而&nbsp;不&nbsp;同&nbsp;了。&nbsp;一&nbsp;个&nbsp;最&nbsp;为&nbsp;普&nbsp;通&nbsp;的&nbsp;方&nbsp;法&nbsp;是&nbsp;使&nbsp;用EPROM&nbsp;或Flash&nbsp;烧&nbsp;录&nbsp;&nbsp;<br />
器，&nbsp;把&nbsp;程&nbsp;序&nbsp;烧&nbsp;录&nbsp;在&nbsp;芯&nbsp;片，&nbsp;然&nbsp;后&nbsp;把&nbsp;芯&nbsp;片&nbsp;插&nbsp;入&nbsp;板&nbsp;上。&nbsp;另&nbsp;外&nbsp;的&nbsp;方&nbsp;法&nbsp;是&nbsp;<br />
&nbsp;通&nbsp;过JTAG&nbsp;接&nbsp;口&nbsp;进&nbsp;行。&nbsp;<br />
9．&nbsp;嵌&nbsp;入&nbsp;式&nbsp;的&nbsp;Linux&nbsp;同&nbsp;样&nbsp;健&nbsp;壮&nbsp;可&nbsp;靠&nbsp;和其他的运行于PC的系统相比，Linux是最&nbsp;<br />
可靠和最稳定的操作系统。而嵌入式的核心也是如此的。Linux的核心移植到新的微处理&nbsp;<br />
器上，基本不用什么修改。因此Linux可以使用许多计算机板。外设的驱动程序也多如牛&nbsp;<br />
毛，而且比其他的都稳定好用。但是，如果不是PC平台环境，那么你必需为特殊硬件编&nbsp;<br />
写驱动程序。对于各种硬件的相似驱动程序市面上随处可见，所以，你可以DOWN下来修&nbsp;<br />
改而成，所以安装新的或特殊&nbsp;驱动器、网卡、串口、并口就不困难了。不过，我还是建&nbsp;<br />
议你在身边放一本Kernel的书比较好，以备查找。&nbsp;在我的经验中，我觉得使用Linux的&nbsp;<br />
错误大都是对系统的了解不准确所至。况且，Linux的源代码随处可得、注释丰富、文档&nbsp;<br />
齐全，你完全可能自己去解决问题。&nbsp;<br />
10．结束语&nbsp;嵌入式的Linux系统也有缺点。和某些商业操作系统一样，占用较大的内存&nbsp;<br />
。当然可以去掉部分无用的功能来减小使用的内存，但是，如果不仔细，将引起新的问&nbsp;<br />
题。&nbsp;有些Linux的应用程序需要虚拟内存，而嵌入式系统中并没有或不需要虚拟内存，&nbsp;<br />
所以，并非所有的Linux应用程序可以在嵌入式系统运行。&nbsp;核心的调试工具并非完尽人&nbsp;<br />
意，虽然可以使用kgdb，不过我们更多的是使用print语句来帮助调试。&nbsp;在应用于嵌入&nbsp;<br />
式系统的主要问题是：Linux本身具有很大的灵活性，而嵌入式系统不具有灵活性，它们&nbsp;<br />
主要针对特殊的问题。这是问题的关键。&nbsp;总之，Linux用于开发嵌入式系统的应用软件&nbsp;<br />
是可能的和可行的。&nbsp;<br />
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