path: root/zh/FAQ/hackers.sgml

<!-- $Id: hackers.sgml,v 1.6 1999-08-11 14:43:28 foxfair Exp $ -->
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  <sect>
    <heading>µ¹¦³¤ß²`¤J¬ã¨sªº FreeBSD hacker <label id="hackers"></heading>

    <sect1>
      <heading>SNAPs ©M RELEASEs ¬O¤°»ò¡H</heading>

      <p>¥Ø«e¦³¤T­Ó¬¡ÅD/¥b¬¡ÅDªº¤À¤ä¦b FreeBSD ªº
      <url url="http://www.FreeBSD.org/cgi/cvsweb.cgi" name="CVS Repository">:

      <itemize>
        <item><bf/RELENG_2_2/   §Y <bf/2.2-stable/ §Y <bf/"2.2 branch"/
        <item><bf/RELENG_3/     §Y <bf/3.x-stable/ §Y <bf/"3.0 branch"/
        <item><bf/HEAD/         §Y <bf/-current/ §Y <bf/4.0-current/
      </itemize>

      <p>¦p¦P¨ä¥L¨â­Ó¡A<bf/HEAD/ ¨Ã¤£¬O¯u¥¿ªº branch tag¡A¥¦¥u¬O¤@­Ó²Å¸¹
      ±`¼Æ¡A«ü¦V <em/"current¡G©|¥¼¤À¤äªºµo®i¤¤ª©¥»"/ ¡A²°O¬°
      <bf/-current/¡C

      <p>¥H²{¦b¨Ó»¡¡A<bf/-current/ ´Â¦V 4.0 µo®i¡A¦Ó <bf/3.0-stable/ ³o
      ­Ó¤À¤ä¡A¤]´N¬O <bf/RELENG_3/¡A¦b 1999 ¦~ 1 ¤ë±q <bf/-current/ ¤À¥X
      ¨Ó¡C

      <p><bf/2.2-stable/ ³o­Ó¤À¤ä¡A¤]´N¬O <bf/RELENG_2_2/¡A¬O¦b 1996 ¦~
      11 ¤ë±q -current ¤À¥X¨Ó¡C

      <p><bf/2.1-stable/ ³o­Ó¤À¤ä¡A¤]´N¬O <bf/RELENG_2_1_0/¡A«h¬O¦b
      1994 ¦~ 9 ¤ë±q -current ¤À¤ä¥X¨Ó¡A³o­Ó¤À¤ä¤w¸g§¹¥þ°h¥ð¤F¡C

    <sect1>
      <heading>
        §Ú­n«ç»ò§@¥X¦Û¤vªº release¡H<label id="custrel">
      </heading>

      <p>°µ release ¥]¬A¤U­±³o¤T­Ó¨BÆJ¡G­º¥ý¡A°µ¥X¦³ <htmlurl 
      url="http://www.FreeBSD.org/cgi/man.cgi?vn" name="vn"> ³o­ÓÅX°Êµ{
      ¦¡ªº¥i¥Î kernel¡C§â¤U­±³o¤@¦æ¥[¨ì kernel ³]©wÀÉ¡AµM«á°µ¥X·sªº
      kernel ­«·s¶}¾÷¡G

      <verb>
        pseudo-device vn         #Vnode driver (turns a file into a device)
      </verb>

      <p>±µµÛ¡A§A¤â¤W­n¦³¾ã­Ó CVS repository¡C¥i¥H°Ñ¦Ò <url
      url="../../handbook/synching.html#CVSUP" name="CVSUP"> ³o½g¤å³¹¡A¦ý¦b
      supfile ¤¤§â release ¦WºÙ³]¦¨ cvs¡A¦A§R±¼©Ò¦³ tag ©Î date ªºÄæ¦ì¡A¦p
      ¤U¡G

      <verb>
        *default prefix=/home/ncvs
        *default base=/a
        *default host=cvsup.FreeBSD.org
        *default release=cvs
        *default delete compress use-rel-suffix

        ## Main Source Tree
        src-all
        src-eBones
        src-secure

        # Other stuff
        ports-all
        www
        doc-all
      </verb>

      <p>µM«á°õ¦æ <tt/cvsup -g supfile/ §â©Ò¦³ªF¦è³£§ì¤U¨Ó...

      <p>³Ì«á¡AµwºÐ­n¦³¬Û·í¤jªºªÅ¶¡¨Ó°µ release¡C°²³]§A·Q§â¥¦©ñ¦b
      <tt>/some/big/filesystem</tt> ³o¸Ì¡A¤W­±³o­Ó¨Ò¤l¤]§â CVS
      repository ©ñ¦b <tt>/home/ncvs</tt> ¤F¡A±µµÛ¡G

      <verb>
        setenv CVSROOT /home/ncvs        # or export CVSROOT=/home/ncvs
        cd /usr/src/release
        make release BUILDNAME=3.0-MY-SNAP CHROOTDIR=/some/big/filesystem/release
      </verb>

      <p>¾ã­Ó release ·|°µ¦b <tt>/some/big/filesystem/release</tt>¡Cµ²§ô
      ®É <tt>/some/big/filesystem/release/R/ftp</tt> ³o­Ó¥Ø¿ý¥i¥Hª½±µ¥Î
      ¨Ó°µ¬° FTP ¦w¸Ë¤è¦¡ªº¨Ó·½¡C¦pªG·Q°µ¥X -current ¥H¥~¤À¤äªº SNAP¡A
      ¦b¤W­± make release ³o¤@¦æ¥[ <tt/RELEASETAG=SOMETAG/¡CÁ|¨Ò¨Ó»¡¡A
      <tt/RELEASETAG=RELENG_2_2/ ³o­Ó°Ñ¼Æ·|°µ­Ó§Y®Éªº 2.2-STABLE snapshot¡C

    <sect1>
      <heading>«ç¼Ë¤~¯à°µ¥X¦Û¤v¥Îªº¦w¸ËºÏ¤ù¡H</heading>

      <p>«Ø¥ß¦w¸ËºÏ¤ù¡BÁÙ¦³°µ¥X source/binary archive¡A³£¬O¥Ñ
      <tt>/usr/src/release/Makefile</tt> ¸Ì­±ªº¦UºØ target ¦Û°Ê²£¥Í¡A³o
      ­ÓÀɮ׸̪º¸ê°TÀ³¸Ó¨¬¥H¶}©l¡C¦ý¬O³o­Ó¹Lµ{²o¯A¨ì make world¡A©Ò¥H·|
      ¥Î¨ì¬Û·í¦hªº®É¶¡©MµwºÐªÅ¶¡¡C

    <sect1>
      <heading>``make world'' §â­ì¨Ó¸Ëªº binary Àɳ£´«±¼¤F¡C</heading>

      <p>¨S¿ù¡A´N¬O³o¼Ë¤l¡C¦p¦W¦r©Ò¥Ü¡A``make world'' ·|­«·s½sĶ¨t²Î¤º«Ø
      ªº¨C­Ó binary ÀÉ¡A³o¼Ë¦bµ²§ô®É´N¥i½T©w¦³­Ó¤@­P¥B°®²bªºÀô¹Ò(©Ò¥H­n
      ªá¤W¦n¤@¬q®É¶¡)¡C

      <p>¦b°õ¦æ ``<tt/make world/'' ©Î ``<tt/make install/'' ®É¡A¦pªG¦³
      ³] <tt/DESTDIR/ ³o­ÓÀô¹ÒÅܼơA·s²£¥Íªº binary ±N·|¸Ë¦b
      <tt>&dollar;&lcub;DESTDIR&rcub;</tt> ¤Uªº¦P¼Ë¥Ø¿ý¾ð¤¤¡C¦ý¦b¬Y¨Ç­×
      §ï shared library ©M­««Ø binary ªºµL¯S©w±¡ªp¤U¡A³o¼Ë°µ¥i¯à·|¨Ï
      ``<tt/make world/'' ¥¢±Ñ¡C

    <sect1>
      <heading>
        ¦b¨t²Î¶}¾÷®É¡A¥X²{ ``(bus speed defaulted)''¡C
      </heading>

      <p>Adaptec 1542 SCSI ¥d¤¹³\¨Ï¥ÎªÌ¥Î³nÅé½Õ¾ã¶×¬y±Æªº¦s¨ú³t«×¡C¦­
      ´Áªº 1542 ÅX°Êµ{¦¡¸Õ¹Ï±N¥¦³]¦¨¥i¥Îªº³Ì§Ö³t«×¡A¦ý«á¨Óµo²{¦b¤@¨Ç
      ¾÷¾¹¤W¤£¯à¥Î¡A©Ò¥H²{¦b­n¦b kernel ³]©w¤¤¥[ ``<tt/TUNE&lowbar;1542/''
      ³o­Ó¿ï¶µ¨Ó±Ò°Ê³o­Ó¥\¯à¡C¦b¤ä´©ªº¾÷¾¹¤W¥Î³o­Ó¿ï¶µ·|¨ÏµwºÐ¦s¨ú§ó
      §Ö¡A¦ý¦b¤£¤ä´©ªº¾÷¾¹¤W¦³¥i¯à·|·´±¼¸ê®Æ¡C

    <sect1>
      <heading>
        §Úªººô¸ô³s½u¤£§Ö¡A¨º¥i¥H¸òµÛ current ªºµo®i¶Ü¡H<label id="ctm">
      </heading>

      <p>¥i¥H¡AÂÇµÛ <url url="../../handbook/synching.html#CTM" name="CTM"> ´N
      ¥i¥H¤£¥Î¤U¶Ç©Ò¦³ªº­ì©l½X¥Ø¿ý¾ð¡C

    <sect1>
      <heading>§A¬O«ç»ò§âµo¦æª©¥»¤¤ªºÀɮפÁ¦¨¤@­Ó­Ó 240k ªº¤pÀɮסH</heading>

      <p>¦b¥H BSD ¬°¥Dªº¸û·s¨t²Î¤¤¡Asplit ¦³­Ó ``<tt/-b/'' ¿ï¶µ¡A¬O¥Î¨Ó
      §âÀÉ®×¥H¥ô·N¼Æ¥Ø byte ¤Á¶}¡C

      <p>³o¸Ì¬O <tt>/usr/src/Makefile</tt> ¤¤ªº¤@­Ó¨Ò¤l¡G

      <verb>
        bin-tarball:
        (cd $&lcub;DISTDIR&rcub;; \
        tar cf - . \
        gzip --no-name -9 -c | \
        split -b 240640 - \
        $&lcub;RELEASEDIR&rcub;/tarballs/bindist/bin_tgz.)
      </verb>

    <sect1>
      <heading>§Ú¦b kernel ¸Ì¥[¤F¨Ç·s¥\¯à¡A­n§â¥¦±Hµ¹½Ö¡H</heading>

      <p>½Ð¬Ý¤@¤U <url url="../../handbook/contrib.html"
      name="Handbook ¤¤¥[¤Jµ{¦¡½Xªº³¡¥÷">¡C

      <p>¦P®É¤]·PÁ§Aªº¶O¤ß¡I

    <sect1>
      <heading>ISA ªº Plug N Play ¥d¬O«ç»ò°»´ú©Mªì©l¤Æªº¡H</heading>

      <p>¥Ñ <url url="mailto:uhclem@nemesis.lonestar.org"
      name="Frank Durda IV"> ©Ò¼g¡G

      <p>²³æªº»¡¡A·í¥D¾÷µo¥X¬O§_¦³ PnP ¥dªº¸ß°Ý°T¸¹®É¡A©Ò¦³ªº PnP
      ·|¦b´X­Ó©T©wªº I/O port §@¦^À³¡C©Ò¥H·í°»´ú PnP ªºµ{¦¡¶}©l®É¡A¥¦
      ·|¥ý°Ý¦³¨S¦³ PnP ¥d¦b¡A±µµÛ©Ò¦³ PnP ¥d·|¦b¥¦©ÒŪªº port ¥H¦Û¤v
      ªº«¬¸¹ &num; §@¦^µª¡A³o¼Ë°»´úµ{¦¡´N·|±o¨ì¤@­Ó wired-OR ``yes'' 
      ªº¼Æ¦r¡A¨ä¤¤¦Ü¤Ö·|¦³¤@­Ó bit ¬O¥´¶}ªº¡CµM«á°»´úµ{¦¡·|­n¨D«¬¸¹
      (¥Ñ Microsoft/Intel«ü©w)¤p©ó X ªº¥d``Â÷½u''¡A¦A¥h¬Ý¬O§_ÁÙ¦³¥d¦^
      µª¦P¼Ëªº¸ß°Ý¡A¦pªG±o¨ì ``<tt/0/''¡A´Nªí¥Ü¨S¦³«¬¸¹¤j©ó X ªº¥d¡C
      ²{¦bµ{¦¡·|°Ý¬O§_¦³«¬¸¹¤p©ó X ªº¥d¡A¦pªG¦³ªº¸Ü¡Aµ{¦¡¦A­n«¬¸¹¤j©ó
      X-(limit/4) ªº¥dÂ÷½u¡AµM«á­«ÂФW­±ªº°Ê§@¡C¥Î³oºØÃþ¦ü binary
      search ªº¤èªk¡A¦b¬Y½d³ò¤º§ä­Ó´X¦¸«á¡A°»´úµ{¦¡³Ì«á·|¦b¾÷¾¹¤¤°Ï¤À
      ¥X©Ò¦³ªº PnP ¥d¡A·j´M¦¸¼Æ¤]»·§C©ó¤@­Ó­Ó§äªº 2^64 ¦¸¡C

      <p>¤@±i¥dªº ID ¥Ñ¨â­Ó 32-bit(©Ò¥H¤W­±¬O 2&circ;64) + 8bit °»¿ù
      ½X²Õ¦¨¡A²Ä¤@­Ó 32 bits ¬O¥Î¨Ó°Ï¤À¦U®a¼t°Óªº¡C³o¨Ç¼t°Ó¨S¦³¥X¨Ó¼á
      ²M¹L¡A¦ý¬Ý¨ÓÀ³°²³]¦P¤@®a¥Xªº¤£¦PºØÃþªº¥dªº¼t°Ó ID ¦³¥i¯à¤£¦P¡C
      ¥Î 32 bits ¥u¨Óªí¥Ü¤£¦P¼t°Óªº·Qªk¹ê¦b¦³ÂI¹LÀY¤F¡C

      <p>²Ä¤G­Ó 32 bits «h¬O«¬¸¹ &num¡B¤A¤Óºô¸ô¦ì§}¡B©Î¤@¨Ç¨Ï³o±i¥d¿W
      ¯Sªº¸ê®Æ¡C°£«D²Ä¤@­Ó 32 bits ¤£¦P¡A§_«h¼t°Ó¤£¥i¯à§@¥X²Ä¤G­Ó 32
      bit ¬Û¦Pªº¨â±i¥d¡C©Ò¥H¦b¤@¥x¾÷¾¹¤¤¥i¥H¦³¦P¼Ëªº¦n´X±i¥d¡AµM¦Ó¥L­Ì
      ¾ã­Ó 64 bits ÁÙ¬O·|³£¤£¤@¼Ë¡C

      <p>³o¨â­Ó 32 bit ¥Ã»·³£¤£¥i¯à¬°¹s¡A³o¨Ï±o³Ì¶}©l binary search ¤¤
      ªº wired-OR ·|±o¨ì¤@­Ó«D¹s¼Æ¦r¡C

      <p>¤@¥¹¨t²Î°Ï¤À¥X©Ò¦³¥dªº ID¡A±µµÛ·|¸g¥Ñ¦P¼Ëªº port ¤@­Ó­Ó­«·s±Ò
      °Ê¨C±i¥d¡A±µµÛ§ä¥X¤wª¾¤¶­±¥d©Ò»Ýªº¸ê·½¡B¦³¨º¨Ç¥i¥H¿ïªº interrupt
      µ¥µ¥¡C©Ò¦³¥d³£·|³Q±½´y¤@¦¸¡A¨Ó¦¬¶°³o¨Ç¸ê®Æ¡C

      <p>³o¨Ç¸ê°T±µµÛ©MµwºÐ¤Wªº ECU ÀɮסB©Î MLB BIOS ¸Ìªº¸ê®Æµ²¦X¦b¤@
      °_¡A³q±`¬Oºî¦X ECU ©M MLB ¸Ìªº BIOS PnP ¸ê®Æ¡A³o¨Ç¶gÃä¨Ã¤£¤ä´©¯u
      ¥¿ªº PnP¡AµM¦Ó°»´úµ{¦¡¦bÀˬd BIOS ©M ECU ¸ê®Æ«á¡A¥¦¥i¥HÁקK PnP
      ¶gÃä©M¨º¨Ç°»´ú¤£¨ìªº¬Û½Ä¬ð¡C

      <p>±µµÛ¦A«×«ô³X³o¨Ç PnP ¶gÃä¡A³o¦¸·|§â¥i¥Îªº I/O¡BDMA¡BIRQ ©M°O
      ¾ÐÅé¬M®gªº¦ì§}³£«ü©wµ¹¥¦­Ì¡C³o¨Ç¶gÃä´N·|¥X²{¦b©Ò«ü©wªº¦a¤è¡Aª½¨ì
      ¤U¤@¦¸­«·s¶}¾÷¬°¤î¡A¤£¹L¤]¨S¦³¤H»¡¤£¯à§â¥¦­ÌÀH®É²¾¨Ó²¾¥h¡C

      <p>¤W­±¦³¬Û·í¦hªºÂ²¤Æ¡A¦ý§AÀ³¸Ó¤w¸g¤F¸Ñ¤j­Pªº¹Lµ{¡C

      <p>Microsoft §âªí¥Ü¦Lªí¾÷ª¬ºAªº´X­Ó¥D­n port ®³¨Ó§@ PnP¡A¥L­Ìªº
      ÅÞ¿è¬O¨S¦³¤@±i¥d·|¦b³o¨Ç¦a¤è¸Ñ½X§@¬Û¤Ïªº I/O cycles¡C¦ý¬O§Ú§ä¨ì
      ¤@´Ú¦­´Á¤´¦bµû¦ô PnP ´£®×®Éªº IBM ­ì¼t printer board¡A¥¦ªº½T¥h¸Ñ
      ¹ï³o¨Çª¬ºA port ªº¼g¤J¸ê®Æ¡A¦ý¬O MS ``»¡¤F´Nºâ''¡C©Ò¥H¥¦­Ìªº½T¦³
      ¹ï¦Lªí¾÷ª¬ºA port ¼g¤J¡AÁÙ¦³Åª¨ú¸Ó¦ì§} + <tt/0x800/¡B©M¥t¤@­Ó¦b
      <tt/0x200/ ¤Î <tt/0x3ff/ ¤§¶¡ªº port¡C

    <sect1>
      <heading>FreeBSD ¬O§_¦³¤ä´© x86 ¥H¥~ªº¾÷¾¹¬[ºc¡H</heading>

      <p>¦³´X¸s¤H¤h¤w¸gªí¥Ü¹ïµo®i¦h¥­¥x FreeBSD ªº¿³½ì¡A¨ä¤¤
      FreeBSD/AXP (ALPHA) §Y¬O¨ä¤¤¬Û·í¦¨¥\ªº¨Ò¤l¡A¥i¥H¦b <url
      url="ftp://ftp.FreeBSD.org/pub/FreeBSD/alpha/"
      name="ftp://ftp.FreeBSD.org/pub/FreeBSD/alpha"> ³o¸Ì¨ú±o¥¦ªº
      3.0 SNAPshot ª©¥»¡CALPHA ª©ªº FreeBSD ¦b¶V¨Ó¶V¦hªº ALPHA ¾÷¾¹¤W
      ¨Ï¥Î¡A¨ä¤¤¥]¬A¤F AlphaStation¡BAXPpci¡BPC164¡BMiata ©M Multia
      ³o´XºØ¡C­nµ¥¨ì¨t²Î¦w¸Ë¤u¨ã§¹¥þ¡B¯à¥Î¥úºÐ¦w¸Ë¡B¥H¤Î¦³¨¬°÷¯à¥Îªº
      port/package ¤§«á¡A§Ú­Ì¤~¥´ºâ§â¥¦·í§@§¹¾ãªºª©¥»¡A©Ò¥H²{¦bÀ³¸Ó§â
      FreeBSD/AXP ·í§@ BETA «~½èªº³nÅé¡C­Y­n¬ÛÃöª¬ªpªº®ø®§¡A½Ð¥[¤J
      <tt>&lt;freebsd-alpha@FreeBSD.org&gt;</tt><ref id="mailing"
      name="mailing list">.

      ¤]¦³¤Hªí¥Ü¹L±N FreeBSD SPARC ª©¥»ªº¿³½ì¡A¦pªG§A·Q°Ñ¥[³o­Ó­pµe¡A
      ½Ð¥[¤J <tt>&lt;freebsd-sparc@FreeBSD.org&gt;
      </tt><ref id="mailing" name="mailing list">¡C¦pªG·Q­nª¾¹DÃö©ó
      ·s¥­¥xªº°Q½×¡A½Ð¥[¤J <tt>&lt;freebsd-platforms@FreeBSD.org&gt;</tt>
      <ref id="mailing" name="mailing list">¡C

    <sect1>
      <heading>§Ú­è­è¼g¤F¬Y­Ó³]³ÆªºÅX°Êµ{¦¡¡A¯à¤£¯àµ¹¥¦¤@­Ó major number¡H
      </heading>

      <p>³o­n¬Ý§A¬O§_¥´ºâ±N³o­ÓÅX°Êµ{¦¡¤½¶}¨Ï¥Î¡A¦pªG¬Oªº¸Ü¡A½Ð§â¥¦ªº­ì©l
         ½X°e¤@¥÷µ¹§Ú­Ì¡AÁÙ¦³ <tt>files.i386</tt> ­×§ïªº³¡¥÷¡Bkernel ³]©w
         Àɼ˥»¡B¥H¤Î¥Î¨Ó²£¥Í³]³ÆÀɪº <htmlurl
         url="http://www.FreeBSD.org/cgi/man.cgi?MAKEDEV" name="MAKEDEV">¡C
         ¦pªG§A¤£¥´ºâ¡B©Î¦]¬°ª©Åv°ÝÃD¦Ó¤£¯à¤½¶}ªº¸Ü¡A§Ú­Ì¦³¯S¦a«O¯d
         character major number 32 ©M block major number 8 µ¹³o¤è­±ªº¨Ï¥Î¡A
         ª½±µ¥Î³o¨â­Ó´N¦n¤F¡C¤£½×¦p¦ó¡A§Ú­Ì³£·|«Ü·P¿E§A¯à¦b
         <tt>&lt;freebsd-hackers@FreeBSD.org&gt;</tt> µoªíÅX°Êµ{¦¡ªº®ø®§¡C

    <sect1>
      <heading>Ãö©ó©ñ¸m¥Ø¿ý©MÀÉ®× inode §@ªk¤Wªº¬Û²§</heading>

      <p>¦b¦^µª¦³Ãö¥Ø¿ý©ñ¸m¤è¦¡¤£¦Pªº°ÝÃD¤W¡A§Ú¦b 1983 ¦~¼g¦n¥Ø«eªº§@ªk
         «á´N¨S¦³¦A§ïÅܹL¡A³oºØ¤è¦¡¬O°w¹ï­ì¥ýªº FFS Àɮרt²Î¡A«á¨Ó¤]¨S
         ¦³¹ï¥¦§@¥ô¦ó§ó°Ê¡C¥¦¦bÁקK cylinder group ³Q¶ñº¡³o¤è­±°µ±o¬Û·í
         ¦¨¥\¡A¦ý¬O´N¹³¦³¨Ç¤H¤w¸gª`·N¨ì¡A¥¦©M `find' ´N°t¦X±o¤£¤j¦n¡C¤j
         ³¡¥÷ªºÀɮרt²Î¬O¥Ñ¨º¨Ç¥Î depth first search(aka ftw) ²£¥Íªº
         archive »s³y¥X¨Ó¡A¸Ñ¥X¨Óªº¥Ø¿ý inode ·|¾î¸ó¦n´X­Ó cylinder
         group¡A¦pªG¥H«á­n°µ depth first search ªº¸Ü¡A³o¬O³ÌÁV¿|ªº±¡ªp¤§
         ¤@¡C¦pªG§Ú­Ìª¾¹DÁ`¦@·|²£¥Í¦h¤Ö¥Ø¿ýªº¸Ü¡A¸Ñªk¬O¦b°µ¥ô¦ó¦s¨ú/¼g
         ¤J°Ê§@¤§«e¡A¦b¨C­Ó cylinder group ¤W¥ý³y¥X(©Ò¦³¥Ø¿ý¼Æ/cylinder
         greoup ªº¼Æ¥Ø)³o»ò¦hªº¥Ø¿ý¡C«Ü©úÅ㪺¡A§Ú­Ì¥²¶·­n¦³®Ú¾Ú¦a¥h²q³o
         ­Ó¼Æ¦r¡A´Nºâ¤@­Ó¹³ 10 ªº«Ü¤p©T©w¼Æ¥Ø¤]·|¨Ï®Ä²v¥H¯Å¼Æ¦¨ªø¡C°Ï¤À
         restore (§Y¸Ñ¶}¤W­zªº archive) ©M¤@¯ëÀÉ®×¾Þ§@ªº¤èªk¥i¥H¬O(²{¦b
         ¥Îªººtºâªk¥i¯à­n§ó±Ó·P)¡G¦pªG¤@¨Ç¥Ø¿ý(³Ì¦h 10 ­Ó)³£¦b 10 ¬í¤º²£
         ¥Íªº¸Ü¡A¨º»ò´N§â³o¨Ç¥Ø¿ý»E¶°¦b¦P¤@­Ó cylinder group¡C¤£ºÞ«ç¼Ë¡A
         §Úªº¸gÅç«ü¥X³o¬O¤@­Ó¤w¸g¥R¥÷¹êÅç¹Lªº³¡¥÷¡C</p>

      <p>Kirk McKusick, September 1998</p>

    <sect1>
      <heading>¦p¦ó±q kernel panic ±o¨ì³Ì¦h¸ê°T¡H</heading>

      <p>      
      <em>[³o¸`¬O±q <url url="mailto:wpaul@FreeBSD.org" name="Bill Paul">
      ¦b freebsd-current <ref id="mailing" name="mailing list"> ¤Wµoªí
      ªº«H¤¤¸`¿ý¡A<url url="mailto:des@FreeBSD.org"
      name="Dag-Erling Co&iuml;dan Sm&oslash;rgrav"> ­×¥¿¤F¥´¦r¿ù»~¡B¦A
      ¥[¤W¬A©·¸Ìªºª`¸Ñ¡C]</em>

      <p>
      <verb>
From: Bill Paul <wpaul@skynet.ctr.columbia.edu>
Subject: Re: the fs fun never stops
To: ben@rosengart.com
Date: Sun, 20 Sep 1998 15:22:50 -0400 (EDT)
Cc: current@FreeBSD.org
      </verb>

      <p>
      <em>[&lt;ben@rosengart.com&gt; µoªí¤F¤U­±ªº panic °T®§]</em>
      <verb>
> Fatal trap 12: page fault while in kernel mode
> fault virtual address   = 0x40
> fault code              = supervisor read, page not present
> instruction pointer     = 0x8:0xf014a7e5
                                ^^^^^^^^^^
> stack pointer           = 0x10:0xf4ed6f24
> frame pointer           = 0x10:0xf4ed6f28
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, def32 1, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 80 (mount)
> interrupt mask          =
> trap number             = 12
> panic: page fault
      </verb>
      
      <p>·í§A¬Ý¨ì¹³³o¼Ëªº°T®§®É¡A¥u§â¥¦«þ¤@¥÷°e¤W¨Ó¬O¤£°÷ªº¡C§Ú¦b¤W
      ­±¯S¦a¼Ð©úªº instruction pointer ­È¬Û·í­«­n¡A¤£©¯ªº¬O¥¦·|¦]³]
      ©w¦Ó¤£¦P¡C´«¥y¸Ü»¡¡A³o­Ó­È·|¸ò§A¥Îªº kernel image ÀɦÓÅÜ°Ê¡C¦p
      ªG¬O¥Î¬Y­Ó snapshot ª©¥»ªº GENERIC kernel¡A¤]³\¨ä¥L¤H¥i¥H°lÂÜ
      ¨ì¥X°ÝÃDªº¨ç¦¡¡A¦ý¦pªG§A¬O¥Î¦Û­qªº kernel¡A¨º»ò¥u¦³<em/§A/¤~¯à
      §i¶D§Ú­Ì°ÝÃD¥X¦b¨º¸Ì¡C

      <p>­n°µªº¨Æ¥]¬A³o¨Ç¡G

      <itemize>
        <item>§â instruction pointer ªº­È°O¤U¨Ó¡Cª`·N¦b«e­±ªº <tt/0x8:/
        ¦b³o­Ó±¡ªp¤¤¨Ã¤£­«­n¡A§Ú­Ì­nªº¬O <tt/0xf0xxxxxx/¡C

	<item>·í¨t²Î­«·s¶}¾÷«á¡A°õ¦æ³o¹D©R¥O¡G
	  <verb>
% nm /(³y¦¨ panic ªº kernel ÀÉ®×) | grep f0xxxxxx
          </verb>	  
     ¨ä¤¤ <tt/f0xxxxxx/ ´N¬O°O¤U¨Óªº instruction pointer ­È¡C¦³¥i¯à
     ¤£·|­è¦n§ä¨ì§¹¾ãªº³o­Ó¦r¦ê¡A³o¬O¦]¬° kernel symbol table ¸Ìªº¦U
     ­Ó symbol ¥u¬O¨ç¦¡ªº¶i¤JÂI¡A¦ý instruction pointer ©Ò«üªº¦ì§}¦³
     ¥i¯à¬O¦b¨ç¦¡¤ºªº¬Y¤@³B¡A¦Ó¤£¤@©w¦b¶}ÀY¡C©Ò¥H¦pªG§ä¤£¨ì¾ã­Ó¦r¦ê¡A
     ¨º»ò§â instruction pointer ­Èªº³Ì«á¤@­Ó¼Æ¦r®³±¼¡A¦A¸Õ¤@¦¸¡G

	  <verb>
% nm /kernel.that.caused.the.panic | grep f0xxxxx
	  </verb>
     ¦pªG³o¼Ë¤]§ä¤£¨ì¡A¨º´N§â¥t¤@­Ó¼Æ¦r¥h±¼¦A§ä¡A¤@ª½­«½Æ¨ì§ä¨ì¬°¤î¡A
     µ²ªG¬O¤@¦ê¥i¯à³y¦¨ panic ªº¨ç¦¡¦Cªí¡C³o¼Ë¤ñª½±µ§ä¨ì¥X°ÝÃDªº¨ç¦¡
     ¨Ó±o®t¡A¦ý¦Ü¤Ö¦n¹L¤°»ò³£¨S¦³¡C
      </itemize>

      <p>§Ú±`±`¬Ý¨ì¤H­ÌÅã¥Ü¤@¤j¤ù panic °T®§¡A¦ý«Ü¤Ö¬Ý¨ì¦³¤Hªá¤@ÂI®É¶¡
      §â instruction pointer ©M kernel symbol table ¤¤ªº¨ç¦¡¤ñ¸û¤@¤U¡C

      <p>­n°lÂÜ¥X³y¦¨ panic ­ì¦]ªº³Ì¦n¤èªk¬O¥ý°µ¥X crash dump¡AµM«á¥Î
      <tt/gdb(1)/ ¦b¤W­±°µ stack trace¡C·íµM¡A³o­n¾a -current ¤¤ªº
      <tt/gdb(1)/ ¯à¹B§@¥¿±`¡AµM¦Ó§ÚµLªk«OÃÒ³o¤@ÂI¡C(°O±o¦³¤H»¡ ELF ªº
      <tt/gdb(1)/ ¦b kernel ªº crash dump ¤W¤£¯à¥¿±`¾Þ§@¡A¦b 3.0 ²æÂ÷
      BETA ¶¥¬q®É³Ì¦n¦³¤H¥ýÀˬd³o¤è­±ªºª¬ªp¡A§K±o«Ü¦h¤H¦b¦¬¨ì 3.0 ¥úºÐ
      «áµÈ¬õ¤FÁy¡C)

      <p>
      ¤£ºÞ¬O¨º¤@ºØ¡A§Ú³q±`¬O¥Î³o­Ó¤èªk¡G

      <itemize>
        <item>¼g¦n kernel ³]©wÀÉ¡C¦pªG§A»Ý­n¥Î kernel debugger¡A¦b³]©w
        Àɤ¤¥[¤W `options DDB' ³o­Ó¿ï¶µ¡C(·í§ÚÃhºÃ¦³¥X²{µL½a°j°é®É¡A³q
        ±`·|¥Î³o­Ó¨Ó³]©w¤¤Â_ÂI¡C)
        <item>¥Î <tt/config -g KERNELCONFIG/ °µ¥X¥Î¨Ó½sĶªº¥Ø¿ý
        <item><tt>cd /sys/compile/KERNELCONFIG; make</tt>
        <item>µ¥ kernel ½sĶ¥X¨Ó
        <item><tt/cp kernel kernel.debug/
        <item><tt/strip -d kernel/
        <item><tt/mv /kernel /kernel.orig/
        <item><tt>cp kernel /</tt>
        <item>­«·s¶}¾÷
      </itemize>

      <p> <em>[ª`·N¡G²{¦b FreeBSD 3.x kernel ¤º©w¬O ELF ®æ¦¡¡A©Ò¥HÀ³¸Ó
      ¥Î <tt/strip -g/ ¦Ó¤£¬O <tt/strip -d/¡C¦pªG§Aªº kernel ¦]¬YºØ­ì
      ¦]¤´¬O a.out ®æ¦¡ªº¸Ü¡A«h¥Î <tt/strip -aout -d/¡C]</em>

      <p>ª`·N§A<em/¤£·|/¯uªº¥Î¥]¬A©Ò¦³ debug symbol ªº kernel ¨Ó¶}¾÷¡A
      ¥Î <tt/-g/ ½sĶ¥X¨Óªº kernel ¤j¤p«Ü®e©ö´N¶W¹L 10MB¡C¤£»Ý­n¥Î³o»ò
      ¤jªº kernel ¶}¾÷¡A±ß¤@ÂI <tt/gdb(1)/ ¤~·|»Ý­n¥¦(<tt/gdb(1)/ ·|¥Î
      ¨ì¸Ì­±ªº symbol table)¡C©Ò¥H§Ú­Ì¤~·|§â§¹¾ãªº kernel ½Æ»s¤@¥÷¡A±µ
      µÛ¥Î <tt/strip -d/ §R±¼ debug symbol¡A°µ¥X²Ä¤G­Ó kernel¡A³o­Ó¤~¯u
      ¥¿®³¨Ó¶}¾÷¡C

      <p>­n½T©w¯à§ì¨ì crash dump¡A¥ý½s¿è <tt>/etc/rc.conf</tt>¡A±N
      <tt/dumpdev/ «ü¨ì swap ¤À³Î°Ï¡C³o¼Ë <tt/rc(8)/ ·|¥Î <tt/dumpon(8)/
      ¨Ó±Ò°Ê crash dump¡A§A¤]¥i¥H¤â°Ê¥Î <tt/dumpon(8)/¡C¦b panic ¤§«á¡A
      crash dump ¥i¥H¥Î <tt/savecore(8)/ ¦s°_¨Ó¡F¦pªG <tt>/etc/rc.conf</tt>
      ¸Ì¦³³] <tt/dumpdev/¡A¨º»ò­«·s¶}¾÷«á <tt/rc(8)/ ·|¦Û°Ê°õ¦æ
      <tt/savecore(8)/ §â crash dump ¦s¦b <tt>/var/crash</tt>¡C

      <p>ª`·N¡GFreeBSD ªº crash dump ³q±`©M¾÷¾¹¸Ìªº¹ê»Ú°O¾ÐÅé¤@¼Ë¤j¡A
      ´N¹³¦pªG¦³ 64MB °O¾ÐÅé¡Acrash dump ¤j¤p´N¬O 64MB¡C©Ò¥H­n½T©w
      <tt>/var/crash</tt> ¤U¦³¨¬°÷ªºªÅ¶¡¡A©Î¬O¥i¥H¤â°Ê°õ¦æ <tt/savecore(8)/
      §â crash dump ©ñ¨ì¥t¤@­ÓªÅ¶¡¸û°÷ªº¥Ø¿ý¤U¡C¥t¤@ºØ¤]³\¥i¥H­­¨î crash
      dump ªº¤èªk¡A¬O¦b kernel ³]©wÀɤ¤¥Î <tt/options MAXMEM=(foo)/¡A
      ±N kernel ¥i¥Îªº°O¾ÐÅé­­¨î¦b¦X²zªº¤j¤p¡CÁ|¨Ò¨Ó»¡¡A¦pªG§A¦³ 128MB
      ªº°O¾ÐÅé¡A¦ý¬O¥i¥H­­¨î kernel ¥u¯à¥Î 16MB ªº°O¾ÐÅé¡A³o¼Ë crash
      dump ´N¬O 16MB ¦Ó¤£¬O 128MB ¤F¡C

      <p>¤@¥¹µo²{¦³¤F crash dump¡A´N¥i¥H¥Î <tt/gdb(1)/ ¨Ó°µ stack trace
      ¡A¦p¤U©Ò¥Ü¡G

      <p>
      <verb>
% gdb -k /sys/compile/KERNELCONFIG/kernel.debug /var/crash/vmcore.0
(gdb) where
      </verb>

      <p>­nª`·N¥i¯à·|¥X²{¦n´X­Ó¿Ã¹õªº¥i¥Î¸ê°T¡A§A¥i¥H¥Î <tt/script(1)/
      §â©Ò¦³¿é¥X³£¦s°_¨Ó¡C¥Î¥]¬A©Ò¦³ debug symbol ªº kernel ¨Ó°£¿ù¡A
      ³o¼ËÀ³¸Ó¥i¥Hª½±µÅã¥Ü panic ¬Oµo¥Í¦b¨º¤@¦æ¡C³q±`¬O¥Ñ¤U©¹¤WŪ stack
      strace¡A³o¼Ë¤~¯à¤@­Ó­Ó°lÂÜ¥X¦³¨º¨Ç°Ê§@¤Þ¨ì crash¡C¤]¥i¥H¥Î
      <tt/gdb(1)/ §â¦UºØÅܼƩε²ºcªº¤º®e¦L¥X¨Ó¡A¥HÀˬd¨t²Î crash ®Éªº
      ¹ê»Úª¬ºA¡C

      <p>¦n°Õ¡A¦pªG§A¦³²Ä¤G¥x¹q¸£¦Ó¥B¦³°÷ºÆ¨g¡A¥i¥H±N <tt/gdb(1)/ ³]©w
      ¦¨»·ºÝ°£¿ù¡C³o¼Ë§A¥i¥H¦b¤@¥x¾÷¾¹¤¤¥Î <tt/gdb(1)/ ¥h°£¿ù¥t¤@¥x¸Ìªº
      kernel¡A¥i¥H°õ¦æªº¥]¬A³]©w¤¤Â_ÂI¡B¦b kernel ­ì©l½X¤¤¤@¨B¨B°õ¦æµ¥
      µ¥¡A´N¹³¦b¤@¯ë¨Ï¥ÎªÌµ{¦¡¤W°£¿ù¤@¼Ë¡C¥Ñ©ó¨S¦³¤°»ò¾÷·|¬°°£¿ù¦Ó³]¸m
      ¨â¥x¨Ã¾F¹q¸£¡A©Ò¥H§ÚÁÙ¨S¦³³o¼Ëª±¹L¡C

      <p><em>[Bill ªþª`¡G§Ú§Ñ¤F´£¨ì¤@ÂI¡G¦pªG§A¦³±Ò°Ê DDB ¦Ó kernel ¤]
      ¤w¸g¶i¤J°£¿ù¾¹¡A¥i¥H¦b DDB ©R¥O¦C¤U¥´ `panic'¡A±j­¢²£¥Í panic(ÁÙ
      ¦³ crash dump)¡C¤]¦³¥i¯à¦b panic ¶¥¬q®É¦A¶i¤J°£¿ù¾¹¡A¦pªG³o¼Ëªº¸Ü
      ¡A¿é¤J `continue'¡A±µµÛ¥¦´N·|§¹¦¨ crash dump¡C -ed]</em>

    <sect1>
      <heading>dlsym() ¹ï ELF °õ¦æÀɤ£¯à¥Î!</heading>

      <p>¦b ELF ¤@¨t¦Cªº¤u¨ã¤¤¡A¤º©w¬O¤£·|Åý dynamic linker ¬Ý¨ì°õ¦æÀÉ
      ¸Ì©w¸q¤F¨º¨Ç symbol¡C©Ò¥H <tt>dlsym()</tt> ¨S¦³¿ìªk¥ÎÂǥѩI¥s
      <tt>dlopen(NULL, flags)</tt> ¨ú±oªº handle¡A¥Î¥¦¥h·j´M¦³¨º¨Ç
      symbol ¤@©w·|¥¢±Ñ¡C

      <p>¦pªG§A·Q­n¥Î <tt>dlsym()</tt> §ä¥X¬Y­Ó process ªº¥D°õ¦æÀɤ¤
      ¦³¨º¨Ç symbol¡A«h­n¦b link ®É¹ï
      <htmlurl url="http://www.FreeBSD.org/cgi/man.cgi?ld"
      name="ELF linker"> ¥[¤W <tt>-export-dynamic</tt> ³o­Ó°Ñ¼Æ¡C

    <sect1>
      <heading>¼W¥[©Î´î¤Ö kernel ¯à©w§}ªºªÅ¶¡</heading>

      <p>¨t²Îªº¤º©w¬O¡AFreeBSD 3.x kernel ¯à©w§}¨ì 256 MB¡A4.x «h¬O
      1 GB¡C¦pªG¬Oºô¸ô­t²ü¬Û·í­«ªº¦øªA¾¹(´N¹³¤j«¬ FTP ©Î HTTP ¦øªA¾¹)¡A
      256 MB ¥i¯à·|¤£¤j°÷¡C

      <p>­n«ç»ò¼W¥[©w§}ªÅ¶¡©O? ­n±q¨â¤è­±µÛ¤â¡C­º¥ý§i¶D kernel ¥»¨­­n
      «O¯d¸û¤jªÅ¶¡; ¨ä¦¸¡A¬JµM¬O¦b©w§}ªÅ¶¡ªº³Ì¤W­±¸ü¤J kernel¡A©Ò¥HÁÙ
      ­n½Õ§C¸ü¤Jªº¦ì§}¡A§_«h´N·|¶W¹L©w§}½d³ò¡C

      <p>¼W¥[ <tt>src/sys/i386/include/pmap.h</tt> ¸Ìªº <tt/NKPDE/ ­È
      «K¥i¹F¦¨²Ä¤@­Ó¥Ø¼Ð¡C1 GB ªº©w§}ªÅ¶¡·|¹³³o¼Ë¡G

      <verb>
#ifndef NKPDE
#ifdef SMP
#define NKPDE                   254     /* addressable number of page tables/pde's */
#else
#define NKPDE                   255     /* addressable number of page tables/pde's */
#endif  /* SMP */
#endif
      </verb>

      <p>­nºâ¥X <tt/NKPDE/ ªº¥¿½T­È¡A±N·Q­nªºªÅ¶¡¤j¤p(¥H megabyte ¬°³æ
      ¦ì)°£¥H 4¡A±µµÛ³æ CPU ¾÷¾¹´î 1¡AÂù CPU «h¬O´î 2¡C

      <p>­n¸Ñ¨M²Ä¤G­Ó°ÝÃD¡A¥²¶·¦Û¦æºâ¥X kernel ³Q¸ü¤Jªº¦ì§}¡G¨D¥X
      0x100100000 ´î±¼©w§}ªÅ¶¡¤j¤pªº­È(¥H byte ¬°³æ¦ì)¡A¦p 1 GB ¤j¤p´N
      ¬O 0xc0100000¡C§â <tt>src/sys/i386/conf/Makefile.i386</tt> ¸Ìªº
      <tt/LOAD_ADDRESS/ ³]¦¨³o­Ó­È¡A±µµÛ¦b
      <tt>src/sys/i386/conf/kernel.script</tt> ¤¤¡A±N section ¦Cªí³Ì«e­±ªº
      location counter ³]¦¨¬Û¦Pªº­È¡A¦p¤U¡G

      <verb>
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)
ENTRY(btext)
SEARCH_DIR(/usr/lib); SEARCH_DIR(/usr/obj/elf/home/src/tmp/usr/i386-unknown-freebsdelf/lib);
SECTIONS
{
  /* Read-only sections, merged into text segment: */
  . = 0xc0100000 + SIZEOF_HEADERS;
  .interp     : { *(.interp)    }
      </verb>

      <p>µM«á­«·s config ©M°µ¥X·sªº kernel¡C¦b°õ¦æ¹³ <tt/ps(1)/¡B
      <tt/top(1)/ ³oÃþµ{¦¡®É¥i¯à·|¸I¨ì°ÝÃD¡A°µ¤@¦¸ <tt/make world/
      À³¸Ó´N¥i¥H¸Ñ¨M(©Î§â§ï¹Lªº <tt/pmap.h/ «þ¨ì <tt>/usr/include/vm/</tt>
      ¤U¡A¦A¤â°Ê½sĶ <tt/libkvm/¡B<tt/ps/ ©M <tt/top/)¡C

      <p>ª`·N¡Gkernel ©Ò¯à©w§}ªºªÅ¶¡¤j¤p¥²¶·¬O 4 megabytes ªº­¿¼Æ¡C

      <p>[<url url="mailto:dg@FreeBSD.org" name="David Greenman"> ¥[¤W
      ³o¤@¬q¡G<em>§Ú»{¬° kernel ©w§}ªÅ¶¡¤j¤pÀ³¸Ó¬O 2 ªº­¼¾­¡A¦ý¤£¤j½T
      ©w³o¤@ÂI¡Cªº±Ò°Êµ{¦¡·|°Ê¨ì high order address bits¡A°O±o¥¦°²³]
      ¦Ü¤Ö¦³ 256 MB¡C]</em>

  </sect>