{"id":1310,"date":"2012-02-24T05:28:44","date_gmt":"2012-02-23T11:28:44","guid":{"rendered":"http:\/\/peta.okechan.net\/blog\/?p=1310"},"modified":"2016-03-03T17:52:43","modified_gmt":"2016-03-03T08:52:43","slug":"xv6%e3%82%bd%e3%83%bc%e3%82%b9%e3%82%b3%e3%83%bc%e3%83%89%e3%83%aa%e3%83%bc%e3%83%87%e3%82%a3%e3%83%b3%e3%82%b0-%e3%81%9d%e3%81%ae19","status":"publish","type":"post","link":"https:\/\/peta.okechan.net\/blog\/archives\/1310","title":{"rendered":"[xv6 #19] Chapter 1 – The first process – Real world"},"content":{"rendered":"

\u30c6\u30ad\u30b9\u30c8\u306e29\u301c30\u30da\u30fc\u30b8<\/p>\n

\u672c\u6587<\/h3>\n

\u591a\u304f\u306e\u30aa\u30da\u30ec\u30fc\u30c6\u30a3\u30f3\u30b0\u30b7\u30b9\u30c6\u30e0\u306f\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30b3\u30f3\u30bb\u30d7\u30c8\u3092\u63a1\u7528\u3055\u308c\u3001\u5927\u90e8\u5206\u306fxv6\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u985e\u4f3c\u3057\u3066\u3044\u308b\u3002
\n\u5b9f\u969b\u306eOS\u306e\u4e16\u754c\u3067\u306f\u3001allocproc\u3067\u7dda\u5f62\u6642\u9593\u691c\u7d22\u3092\u3059\u308b\u4ee3\u308f\u308a\u306b\u3001\u660e\u793a\u7684\u306a\u7a7a\u304d\u30ea\u30b9\u30c8\u3092\u4f7f\u3063\u3066\u4e00\u5b9a\u306e\u6642\u9593\u3067\u7a7a\u3044\u3066\u3044\u308bproc\u69cb\u9020\u4f53\u3092\u63a2\u3059\u3002
\nxv6\u306f\u5206\u304b\u308a\u3084\u3059\u3055\u3092\u512a\u5148\u3057\u7dda\u5f62\u63a2\u7d22\u3092\u4f7f\u3063\u3066\u3044\u308b\u3002\uff08\u4ed6\u3082\u6700\u521d\u306f\u3060\u3044\u3060\u3044\u305d\u3046\u3060\uff09<\/p>\n

\u5927\u90e8\u5206\u306eOS\u304c\u305d\u3046\u3067\u3042\u308b\u3088\u3046\u306b\u3001xv6\u3082\u30de\u30c3\u30d4\u30f3\u30b0\u3068\u4fdd\u8b77\u306e\u305f\u3081\u306b\u30da\u30fc\u30b8\u30f3\u30b0\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u3092\u5229\u7528\u3059\u308b\u3002
\n\u5927\u90e8\u5206\u306eOS\u3067\u306f\u3001xv6\u3088\u308a\u30da\u30fc\u30b8\u30f3\u30b0\u306e\u4f7f\u3044\u65b9\u304c\u6d17\u7df4\u3055\u308c\u3066\u3044\u308b\u3002
\n\u4f8b\u3048\u3070\u3001xv6\u306f\u30c7\u30a3\u30b9\u30af\u3078\u306e\u30da\u30fc\u30b8\u30f3\u30b0\u8981\u6c42\u3084fork\u6642\u306ecopy-on-write\u3084\u5171\u6709\u30e1\u30e2\u30ea\u3084\u30b9\u30bf\u30c3\u30af\u306e\u52d5\u7684\u62e1\u5f35\u306a\u3069\u306e\u6a5f\u80fd\u3092\u6b20\u3044\u3066\u3044\u308b\u3002
\n\uff08\u30c7\u30a3\u30b9\u30af\u3078\u306e\u30da\u30fc\u30b8\u30f3\u30b0\u8981\u6c42\u304c\u306a\u3044\uff1d\u3044\u308f\u3086\u308b\u30c7\u30a3\u30b9\u30af\u30b9\u30ef\u30c3\u30d7\u306e\u6a5f\u80fd\u304c\u306a\u3044\u3002\u3042\u3068fork\u6642\u306bCOW\u3057\u306a\u3044\u3068\u3044\u3046\u3053\u3068\u306ffork\u306e\u77ac\u9593\u306b\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u305f\u3081\u30e1\u30e2\u30ea\u52b9\u7387\u3084\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u52a3\u308b\u3053\u3068\u306b\u306a\u308b\u3002\uff09
\nx86\u3082\u307e\u305f\u30bb\u30b0\u30e1\u30f3\u30c8\u3092\u4f7f\u3063\u305f\u30a2\u30c9\u30ec\u30b9\u5909\u63db\u3092\u30b5\u30dd\u30fc\u30c8\u3059\u308b\u304c\u3001xv6\u306f\u9055\u3046CPU\u3067\u9055\u3046\u5024\u3092\u6301\u3061\u306a\u304c\u3089\u540c\u3058\u56fa\u5b9a\u30a2\u30c9\u30ec\u30b9\u306b\u3042\u308bproc\u306e\u3088\u3046\u306b\u3001CPU\u3054\u3068\u306e\u5024\u3092\u6301\u3064\u3053\u3068\u3092\u5b9f\u88c5\u3059\u308b\u305f\u3081\u306e\u304a\u6c7a\u307e\u308a\u306e\u30c8\u30ea\u30c3\u30af\u306e\u305f\u3081\u3060\u3051\u306b\u4f7f\u3046\u3002\uff08seginit\u53c2\u7167\uff09
\n\u30bb\u30b0\u30e1\u30f3\u30c8\u306b\u5bfe\u5fdc\u3057\u3066\u306a\u3044\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u306b\u304a\u3051\u308bCPU\u3054\u3068\uff08\u3082\u3057\u304f\u306f\u30b9\u30ec\u30c3\u30c9\u3054\u3068\uff09\u306e\u30b9\u30c8\u30ec\u30fc\u30b8\u306e\u5b9f\u88c5\u3067\u306f\u3001CPU\u3054\u3068\u306e\u30c7\u30fc\u30bf\u9818\u57df\u3092\u6307\u3059\u30dd\u30a4\u30f3\u30bf\u3092\u4fdd\u6301\u3059\u308b\u305f\u3081\u306b\u30ec\u30b8\u30b9\u30bf\u3092\u5c02\u6709\u3059\u308b\u3060\u308d\u3046\u3002
\n\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u6a5f\u80fd\u3092\u4f7f\u3046\u4e8b\u306f\u8ffd\u52a0\u306e\u52b4\u529b\u3092\u5fc5\u8981\u3068\u3059\u308b\u304c\u3001x86\u306f\u305d\u306e\u3088\u3046\u306b\u4f7f\u3048\u308b\u3044\u304f\u3064\u304b\u306e\u6c4e\u7528\u7684\u306a\u30ec\u30b8\u30b9\u30bf\u3092\u6301\u3063\u3066\u3044\u3066\u3001\u305d\u308c\u306b\u52b4\u529b\u3092\u8cbb\u3084\u3059\u4fa1\u5024\u306f\u3042\u308b\u3002<\/p>\n

vm.c\u306eseginit\u95a2\u6570<\/p>\n

\/\/ Set up CPU's kernel segment descriptors.\r\n\/\/ Run once on entry on each CPU.\r\nvoid\r\nseginit(void)\r\n{\r\n  struct cpu *c;\r\n\r\n  \/\/ Map "logical" addresses to virtual addresses using identity map.\r\n  \/\/ Cannot share a CODE descriptor for both kernel and user\r\n  \/\/ because it would have to have DPL_USR, but the CPU forbids\r\n  \/\/ an interrupt from CPL=0 to DPL=3.\r\n  c = &cpus[cpunum()];\r\n  c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);\r\n  c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);\r\n  c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER);\r\n  c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER);\r\n\r\n  \/\/ Map cpu, and curproc\r\n  c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);\r\n\r\n  lgdt(c->gdt, sizeof(c->gdt));\r\n  loadgs(SEG_KCPU << 3);\r\n  \r\n  \/\/ Initialize cpu-local storage.\r\n  cpu = c;\r\n  proc = 0;\r\n}<\/pre>\n
xv6\u306e\u30a2\u30c9\u30ec\u30b9\u7a7a\u9593\u306e\u30ec\u30a4\u30a2\u30a6\u30c8\u306f\u30012GB\u4ee5\u4e0a\u306e\u7269\u7406\u30e1\u30e2\u30ea\u3092\u6271\u3048\u306a\u3044\u3068\u3044\u3046\u6b20\u70b9\u304c\u3042\u308b\u3002
\n\u305d\u308c\u306f\u4fee\u6b63\u53ef\u80fd\u3067\u306f\u3042\u308b\u304c\u3001\u4e00\u756a\u3044\u3044\u306e\u306f64\u30d3\u30c3\u30c8\u30a2\u30c9\u30ec\u30b9\u306e\u30de\u30b7\u30f3\u306b\u5207\u308a\u66ff\u3048\u308b\u4e8b\u3060\u308d\u3046\u3002<\/p>\n
xv6\u306f\u3001240MB\u3068\u4eee\u5b9a\u3057\u305f\u5206\u306e\u4ee3\u308f\u308a\u306b\u5b9f\u969b\u306eRAM\u306e\u8a2d\u5b9a\u3092\u6c7a\u5b9a\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\nx86\u3067\u306f\u3001\u3088\u304f\u77e5\u3089\u308c\u305f\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306f\u5c11\u306a\u304f\u3068\u30823\u3064\u3042\u308b\u3002
\n1\u3064\u76ee\u306f\u3001\u4e8b\u524d\u306b\u7528\u610f\u3057\u305f\u5024\u3092\u66f8\u304d\u3053\u3093\u3067\u3001\u30e1\u30e2\u30ea\u306e\u3088\u3046\u306b\u632f\u821e\u3046\u3088\u3046\u306b\u898b\u3048\u308b\u7269\u7406\u30a2\u30c9\u30ec\u30b9\u7a7a\u9593\u4e0a\u306e\u9818\u57df\u3092\u8d70\u67fb\u3059\u308b\u65b9\u6cd5\u3067\u3042\u308b\u3002
\n2\u3064\u76ee\u306f\u3001PC\u306e\u4e0d\u63ee\u767a\u306aRAM\u306b\u3042\u308b\u77e5\u3089\u308c\u305f16\u30d3\u30c3\u30c8\u306e\u4f4d\u7f6e\u306e\u5916\u306b\u3042\u308b\u30e1\u30e2\u30ea\u306e\u30ad\u30ed\u30d0\u30a4\u30c8\u6570\u3092\u8aad\u307f\u53d6\u308b\u3053\u3068\u3067\u3042\u308b\u3002
\n3\u3064\u76ee\u306f\u3001BIOS\u30e1\u30e2\u30ea\u306e\u4e2d\u304b\u3089\u3001\u30de\u30eb\u30c1\u30d7\u30ed\u30bb\u30c3\u30b5\u30c6\u30fc\u30d6\u30eb\u306e\u4e00\u90e8\u306e\u3088\u3046\u306b\u3001\u6b8b\u3063\u3066\u3044\u308b\u30e1\u30e2\u30ea\u30ec\u30a4\u30a2\u30a6\u30c8\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3059\u308b\u3053\u3068\u3067\u3042\u308b\u3002
\n\u30e1\u30e2\u30ea\u30ec\u30a4\u30a2\u30a6\u30c8\u30c6\u30fc\u30d6\u30eb\u3092\u8aad\u307f\u53d6\u308b\u3053\u3068\u306f\u8907\u96d1\u3067\u3042\u308b\u3002<\/p>\n
\u5927\u6614\u306f\u3001\u30e1\u30e2\u30ea\u306e\u5272\u308a\u5f53\u3066\u306e\u8a71\u984c\u3067\u6301\u3061\u304d\u308a\u3060\u3063\u305f\u3002
\n\u975e\u5e38\u306b\u9650\u5b9a\u3055\u308c\u305f\u30e1\u30e2\u30ea\u306e\u4f7f\u3044\u65b9\u3092\u52b9\u7387\u5316\u3059\u308b\u3053\u3068\u3084\u3001\u4e0d\u660e\u306a\u5c06\u6765\u306e\u8981\u6c42\u306b\u5099\u3048\u308b\u3053\u3068\u306f\u3001\u57fa\u672c\u7684\u306a\u554f\u984c\u3060\u3063\u305f\u3002
\nKnuth\u3092\u898b\u308d\u3002
\n\u4eca\u65e5\u3067\u306f\u3001\u4eba\u3005\u306f\u9818\u57df\u306e\u52b9\u7387\u5316\u3088\u308a\u901f\u5ea6\u306b\u3064\u3044\u3066\u6c17\u306b\u3057\u3066\u3044\u308b\u3002
\n\u4ed8\u3051\u8db3\u3059\u3068\u3001\u3088\u308a\u8907\u96d1\u306a\u30ab\u30fc\u30cd\u30eb\u306f\u307b\u307c\u9593\u9055\u3044\u7121\u304f\u3001\uff08xv6\u306e\u3088\u3046\u306b\uff094096\u30d0\u30a4\u30c8\u3061\u3087\u3046\u3069\u306e\u30d6\u30ed\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u5c0f\u3055\u3044\u30d6\u30ed\u30c3\u30af\u3067\u69cb\u6210\u3055\u308c\u308b\u69d8\u3005\u306a\u30b5\u30a4\u30ba\u3092\u5272\u308a\u5f53\u3066\u308b\u3060\u308d\u3046\u3002
\n\u5b9f\u969b\u306e\u30ab\u30fc\u30cd\u30eb\u306e\u30a2\u30ed\u30b1\u30fc\u30bf\u306f\u3001\u5927\u304d\u306a\u9818\u57df\u306e\u5272\u308a\u5f53\u3066\u3068\u540c\u3058\u304f\u3089\u3044\u5c0f\u3055\u306a\u9818\u57df\u306e\u5272\u308a\u5f53\u3066\u3082\u6271\u3048\u308b\u5fc5\u8981\u304c\u3042\u308b\u3060\u308d\u3046\u3002<\/p>\n
exec\u306fxv6\u306e\u4e2d\u3067\u4e00\u756a\u8907\u96d1\u306a\u30b3\u30fc\u30c9\u3067\u3042\u308b\u3002
\n\u305d\u308c\u306f\u30dd\u30a4\u30f3\u30bf\u306e\u5909\u63db\u3092\u4f34\u3044\uff08\u305d\u308c\u306fsys_exec\u3067\u3082\u540c\u3058\u3067\u3042\u308b\uff09\u3001\u30a8\u30e9\u30fc\u306b\u306a\u308b\u5834\u5408\u304c\u305f\u304f\u3055\u3093\u3042\u308a\u3001\u5b9f\u884c\u4e2d\u306e\u30d7\u30ed\u30bb\u30b9\u3092\u4ed6\u3067\u7f6e\u304d\u63db\u3048\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u5b9f\u969b\u306eOS\u3067\u306f\u3001exec\u306e\u5b9f\u88c5\u306f\u305d\u308c\u4ee5\u4e0a\u306b\u8907\u96d1\u3060\u3002
\n\u305d\u308c\u3089\u306f\u3001\u30b7\u30a7\u30eb\u30b9\u30af\u30ea\u30d7\u30c8\u3084\uff08\u6b21\u306eexercise\u3092\u53c2\u7167\uff09\u3001\u3082\u3063\u3068\u8907\u96d1\u306aELF\u30d0\u30a4\u30ca\u30ea\u3084\u3001\u8907\u5408\u7684\u306a\u30d0\u30a4\u30ca\u30ea\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3092\u6271\u3046\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
\u5b9f\u969b\u306eOS\u306b\u304a\u3051\u308b\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u306e\u6982\u8981\u3067\u3059\u306d\u3002<\/p>\n
x86\u3067\u5b9f\u969b\u306e\u7269\u7406\u30e1\u30e2\u30ea\u91cf\u3092\u691c\u51fa\u3059\u308b\u6709\u540d\u306a\u65b9\u6cd5\u304c3\u3064\u3042\u308b\u3088\u3046\u3067\u3059\u3002
\n\u8a73\u7d30\u306f\u4e0d\u660e\u3067\u3059\u304c\u30011\u3064\u76ee\u306f\u5168\u8d70\u67fb\u3059\u308b\u65b9\u6cd5\u30012\u3064\u76ee\u306f\u30e1\u30e2\u30ea\u30c1\u30c3\u30d7\u306e\u60c5\u5831\u3092\u8aad\u53d6\u308b\u65b9\u6cd5\uff08\u591a\u5206\uff09\u30013\u3064\u76ee\u306fBIOS\u304b\u3089\u8aad\u307f\u53d6\u308b\u65b9\u6cd5\u307f\u305f\u3044\u3067\u3059\u3002
\n\u3067BIOS\u304b\u3089\u8aad\u307f\u53d6\u308b\u306e\u306f\u591a\u5206\u3044\u308d\u3093\u306a\u5834\u5408\u304c\u3042\u3063\u3066\u96e3\u3057\u3044\u3093\u3067\u3057\u3087\u3046\u306d\u3002<\/p>\n
\u30af\u30cc\u30fc\u30b9\u3092\u898b\u308d\u306e\u6240\u306f\u3088\u304f\u5206\u304b\u308a\u307e\u305b\u3093\u3002
\n\u30af\u30cc\u30fc\u30b9\u306f\u51c4\u3044\u4eba\u306a\u306e\u3067\u3001\u5f7c\u306e\u8003\u3048\u51fa\u3057\u305f\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u304c\u4eca\u65e5\u3082\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u3068\u3057\u3066\u751f\u304b\u3055\u308c\u3066\u308b\u3068\u304b\u3001\u5f53\u6642\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u306b\u95a2\u3059\u308b\u8b70\u8ad6\u3092\u76db\u3093\u306b\u884c\u306a\u3063\u305f\u308a\u3068\u304b\u666e\u901a\u306b\u3042\u308a\u305d\u3046\u3067\u3059\u304c\u3001\u5177\u4f53\u7684\u306a\u4f8b\u306f\u77e5\u308a\u307e\u305b\u3093\u3002
\n\u77e5\u3063\u305f\u3089\u3078\u3047\u301c\u30dc\u30bf\u30f3\u309220\u9023\u6253\u3057\u305f\u304f\u306a\u308b\u3088\u3046\u306a\u30ec\u30d9\u30eb\u306e\u4e8b\u3060\u308d\u3046\u306a\u3068\u3044\u3046\u6c17\u304c\u3057\u3066\u3001\u3061\u3087\u3063\u3068\u8abf\u3079\u3066\u307f\u305f\u3093\u3067\u3059\u304c\u3001\u3053\u308c\u304b\uff01\u3068\u3044\u3046\u306e\u306f\u898b\u3064\u3051\u308c\u307e\u305b\u3093\u3067\u3057\u305f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u30c6\u30ad\u30b9\u30c8\u306e29\u301c30\u30da\u30fc\u30b8<\/p>\n
\u672c\u6587<\/h3>\n
\u591a\u304f\u306e\u30aa\u30da\u30ec\u30fc\u30c6\u30a3\u30f3\u30b0\u30b7\u30b9\u30c6\u30e0\u306f\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u30b3\u30f3\u30bb\u30d7\u30c8\u3092\u63a1\u7528\u3055\u308c\u3001\u5927\u90e8\u5206\u306fxv6\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u985e\u4f3c\u3057\u3066\u3044\u308b\u3002
\n\u5b9f\u969b\u306eOS\u306e\u4e16\u754c\u3067\u306f\u3001allocproc\u3067\u7dda\u5f62\u6642\u9593\u691c\u7d22\u3092\u3059\u308b\u4ee3\u308f\u308a\u306b\u3001\u660e\u793a\u7684\u306a\u7a7a\u304d\u30ea\u30b9\u30c8\u3092\u4f7f\u3063\u3066\u4e00\u5b9a\u306e\u6642\u9593\u3067\u7a7a\u3044\u3066\u3044\u308bproc\u69cb\u9020\u4f53\u3092\u63a2\u3059\u3002
\nxv6\u306f\u5206\u304b\u308a\u3084\u3059\u3055\u3092\u512a\u5148\u3057\u7dda\u5f62\u63a2\u7d22\u3092\u4f7f\u3063\u3066\u3044\u308b\u3002\uff08\u4ed6\u3082\u6700\u521d\u306f\u3060\u3044\u3060\u3044\u305d\u3046\u3060\uff09<\/p>\n
\u5927\u90e8\u5206\u306eOS\u304c\u305d\u3046\u3067\u3042\u308b\u3088\u3046\u306b\u3001xv6\u3082\u30de\u30c3\u30d4\u30f3\u30b0\u3068\u4fdd\u8b77\u306e\u305f\u3081\u306b\u30da\u30fc\u30b8\u30f3\u30b0\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u3092\u5229\u7528\u3059\u308b\u3002
\n\u5927\u90e8\u5206\u306eOS\u3067\u306f\u3001xv6\u3088\u308a\u30da\u30fc\u30b8\u30f3\u30b0\u306e\u4f7f\u3044\u65b9\u304c\u6d17\u7df4\u3055\u308c\u3066\u3044\u308b\u3002
\n\u4f8b\u3048\u3070\u3001xv6\u306f\u30c7\u30a3\u30b9\u30af\u3078\u306e\u30da\u30fc\u30b8\u30f3\u30b0\u8981\u6c42\u3084fork\u6642\u306ecopy-on-write\u3084\u5171\u6709\u30e1\u30e2\u30ea\u3084\u30b9\u30bf\u30c3\u30af\u306e\u52d5\u7684\u62e1\u5f35\u306a\u3069\u306e\u6a5f\u80fd\u3092\u6b20\u3044\u3066\u3044\u308b\u3002
\n\uff08\u30c7\u30a3\u30b9\u30af\u3078\u306e\u30da\u30fc\u30b8\u30f3\u30b0\u8981\u6c42\u304c\u306a\u3044\uff1d\u3044\u308f\u3086\u308b\u30c7\u30a3\u30b9\u30af\u30b9\u30ef\u30c3\u30d7\u306e\u6a5f\u80fd\u304c\u306a\u3044\u3002\u3042\u3068fork\u6642\u306bCOW\u3057\u306a\u3044\u3068\u3044\u3046\u3053\u3068\u306ffork\u306e\u77ac\u9593\u306b\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u305f\u3081\u30e1\u30e2\u30ea\u52b9\u7387\u3084\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u52a3\u308b\u3053\u3068\u306b\u306a\u308b\u3002\uff09
\nx86\u3082\u307e\u305f\u30bb\u30b0\u30e1\u30f3\u30c8\u3092\u4f7f\u3063\u305f\u30a2\u30c9\u30ec\u30b9\u5909\u63db\u3092\u30b5\u30dd\u30fc\u30c8\u3059\u308b\u304c\u3001xv6\u306f\u9055\u3046CPU\u3067\u9055\u3046\u5024\u3092\u6301\u3061\u306a\u304c\u3089\u540c\u3058\u56fa\u5b9a\u30a2\u30c9\u30ec\u30b9\u306b\u3042\u308bproc\u306e\u3088\u3046\u306b\u3001CPU\u3054\u3068\u306e\u5024\u3092\u6301\u3064\u3053\u3068\u3092\u5b9f\u88c5\u3059\u308b\u305f\u3081\u306e\u304a\u6c7a\u307e\u308a\u306e\u30c8\u30ea\u30c3\u30af\u306e\u305f\u3081\u3060\u3051\u306b\u4f7f\u3046\u3002\uff08seginit\u53c2\u7167\uff09
\n\u30bb\u30b0\u30e1\u30f3\u30c8\u306b\u5bfe\u5fdc\u3057\u3066\u306a\u3044\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u306b\u304a\u3051\u308bCPU\u3054\u3068\uff08\u3082\u3057\u304f\u306f\u30b9\u30ec\u30c3\u30c9\u3054\u3068\uff09\u306e\u30b9\u30c8\u30ec\u30fc\u30b8\u306e\u5b9f\u88c5\u3067\u306f\u3001CPU\u3054\u3068\u306e\u30c7\u30fc\u30bf\u9818\u57df\u3092\u6307\u3059\u30dd\u30a4\u30f3\u30bf\u3092\u4fdd\u6301\u3059\u308b\u305f\u3081\u306b\u30ec\u30b8\u30b9\u30bf\u3092\u5c02\u6709\u3059\u308b\u3060\u308d\u3046\u3002
\n\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u6a5f\u80fd\u3092\u4f7f\u3046\u4e8b\u306f\u8ffd\u52a0\u306e\u52b4\u529b\u3092\u5fc5\u8981\u3068\u3059\u308b\u304c\u3001x86\u306f\u305d\u306e\u3088\u3046\u306b\u4f7f\u3048\u308b\u3044\u304f\u3064\u304b\u306e\u6c4e\u7528\u7684\u306a\u30ec\u30b8\u30b9\u30bf\u3092\u6301\u3063\u3066\u3044\u3066\u3001\u305d\u308c\u306b\u52b4\u529b\u3092\u8cbb\u3084\u3059\u4fa1\u5024\u306f\u3042\u308b\u3002<\/p>\n
vm.c\u306eseginit\u95a2\u6570<\/p>\n
\/\/ Set up CPU's kernel segment descriptors.\r\n\/\/ Run once on entry on each CPU.\r\nvoid\r\nseginit(void)\r\n{\r\n  struct cpu *c;\r\n\r\n  \/\/ Map "logical" addresses to virtual addresses using identity map.\r\n  \/\/ Cannot share a CODE descriptor for both kernel and user\r\n  \/\/ because it would have to have DPL_USR, but the CPU forbids\r\n  \/\/ an interrupt from CPL=0 to DPL=3.\r\n  c = &cpus[cpunum()];\r\n  c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);\r\n  c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);\r\n  c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER);\r\n  c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER);\r\n\r\n  \/\/ Map cpu, and curproc\r\n  c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);\r\n\r\n  lgdt(c->gdt, sizeof(c->gdt));\r\n  loadgs(SEG_KCPU << 3);\r\n  \r\n  \/\/ Initialize cpu-local storage.\r\n  cpu = c;\r\n  proc = 0;\r\n}<\/pre>\n
xv6\u306e\u30a2\u30c9\u30ec\u30b9\u7a7a\u9593\u306e\u30ec\u30a4\u30a2\u30a6\u30c8\u306f\u30012GB\u4ee5\u4e0a\u306e\u7269\u7406\u30e1\u30e2\u30ea\u3092\u6271\u3048\u306a\u3044\u3068\u3044\u3046\u6b20\u70b9\u304c\u3042\u308b\u3002
\n\u305d\u308c\u306f\u4fee\u6b63\u53ef\u80fd\u3067\u306f\u3042\u308b\u304c\u3001\u4e00\u756a\u3044\u3044\u306e\u306f64\u30d3\u30c3\u30c8\u30a2\u30c9\u30ec\u30b9\u306e\u30de\u30b7\u30f3\u306b\u5207\u308a\u66ff\u3048\u308b\u4e8b\u3060\u308d\u3046\u3002<\/p>\n
xv6\u306f\u3001240MB\u3068\u4eee\u5b9a\u3057\u305f\u5206\u306e\u4ee3\u308f\u308a\u306b\u5b9f\u969b\u306eRAM\u306e\u8a2d\u5b9a\u3092\u6c7a\u5b9a\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\nx86\u3067\u306f\u3001\u3088\u304f\u77e5\u3089\u308c\u305f\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u306f\u5c11\u306a\u304f\u3068\u30823\u3064\u3042\u308b\u3002
\n1\u3064\u76ee\u306f\u3001\u4e8b\u524d\u306b\u7528\u610f\u3057\u305f\u5024\u3092\u66f8\u304d\u3053\u3093\u3067\u3001\u30e1\u30e2\u30ea\u306e\u3088\u3046\u306b\u632f\u821e\u3046\u3088\u3046\u306b\u898b\u3048\u308b\u7269\u7406\u30a2\u30c9\u30ec\u30b9\u7a7a\u9593\u4e0a\u306e\u9818\u57df\u3092\u8d70\u67fb\u3059\u308b\u65b9\u6cd5\u3067\u3042\u308b\u3002
\n2\u3064\u76ee\u306f\u3001PC\u306e\u4e0d\u63ee\u767a\u306aRAM\u306b\u3042\u308b\u77e5\u3089\u308c\u305f16\u30d3\u30c3\u30c8\u306e\u4f4d\u7f6e\u306e\u5916\u306b\u3042\u308b\u30e1\u30e2\u30ea\u306e\u30ad\u30ed\u30d0\u30a4\u30c8\u6570\u3092\u8aad\u307f\u53d6\u308b\u3053\u3068\u3067\u3042\u308b\u3002
\n3\u3064\u76ee\u306f\u3001BIOS\u30e1\u30e2\u30ea\u306e\u4e2d\u304b\u3089\u3001\u30de\u30eb\u30c1\u30d7\u30ed\u30bb\u30c3\u30b5\u30c6\u30fc\u30d6\u30eb\u306e\u4e00\u90e8\u306e\u3088\u3046\u306b\u3001\u6b8b\u3063\u3066\u3044\u308b\u30e1\u30e2\u30ea\u30ec\u30a4\u30a2\u30a6\u30c8\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3059\u308b\u3053\u3068\u3067\u3042\u308b\u3002
\n\u30e1\u30e2\u30ea\u30ec\u30a4\u30a2\u30a6\u30c8\u30c6\u30fc\u30d6\u30eb\u3092\u8aad\u307f\u53d6\u308b\u3053\u3068\u306f\u8907\u96d1\u3067\u3042\u308b\u3002<\/p>\n
\u5927\u6614\u306f\u3001\u30e1\u30e2\u30ea\u306e\u5272\u308a\u5f53\u3066\u306e\u8a71\u984c\u3067\u6301\u3061\u304d\u308a\u3060\u3063\u305f\u3002
\n\u975e\u5e38\u306b\u9650\u5b9a\u3055\u308c\u305f\u30e1\u30e2\u30ea\u306e\u4f7f\u3044\u65b9\u3092\u52b9\u7387\u5316\u3059\u308b\u3053\u3068\u3084\u3001\u4e0d\u660e\u306a\u5c06\u6765\u306e\u8981\u6c42\u306b\u5099\u3048\u308b\u3053\u3068\u306f\u3001\u57fa\u672c\u7684\u306a\u554f\u984c\u3060\u3063\u305f\u3002
\nKnuth\u3092\u898b\u308d\u3002
\n\u4eca\u65e5\u3067\u306f\u3001\u4eba\u3005\u306f\u9818\u57df\u306e\u52b9\u7387\u5316\u3088\u308a\u901f\u5ea6\u306b\u3064\u3044\u3066\u6c17\u306b\u3057\u3066\u3044\u308b\u3002
\n\u4ed8\u3051\u8db3\u3059\u3068\u3001\u3088\u308a\u8907\u96d1\u306a\u30ab\u30fc\u30cd\u30eb\u306f\u307b\u307c\u9593\u9055\u3044\u7121\u304f\u3001\uff08xv6\u306e\u3088\u3046\u306b\uff094096\u30d0\u30a4\u30c8\u3061\u3087\u3046\u3069\u306e\u30d6\u30ed\u30c3\u30af\u3067\u306f\u306a\u304f\u3001\u5c0f\u3055\u3044\u30d6\u30ed\u30c3\u30af\u3067\u69cb\u6210\u3055\u308c\u308b\u69d8\u3005\u306a\u30b5\u30a4\u30ba\u3092\u5272\u308a\u5f53\u3066\u308b\u3060\u308d\u3046\u3002
\n\u5b9f\u969b\u306e\u30ab\u30fc\u30cd\u30eb\u306e\u30a2\u30ed\u30b1\u30fc\u30bf\u306f\u3001\u5927\u304d\u306a\u9818\u57df\u306e\u5272\u308a\u5f53\u3066\u3068\u540c\u3058\u304f\u3089\u3044\u5c0f\u3055\u306a\u9818\u57df\u306e\u5272\u308a\u5f53\u3066\u3082\u6271\u3048\u308b\u5fc5\u8981\u304c\u3042\u308b\u3060\u308d\u3046\u3002<\/p>\n
exec\u306fxv6\u306e\u4e2d\u3067\u4e00\u756a\u8907\u96d1\u306a\u30b3\u30fc\u30c9\u3067\u3042\u308b\u3002
\n\u305d\u308c\u306f\u30dd\u30a4\u30f3\u30bf\u306e\u5909\u63db\u3092\u4f34\u3044\uff08\u305d\u308c\u306fsys_exec\u3067\u3082\u540c\u3058\u3067\u3042\u308b\uff09\u3001\u30a8\u30e9\u30fc\u306b\u306a\u308b\u5834\u5408\u304c\u305f\u304f\u3055\u3093\u3042\u308a\u3001\u5b9f\u884c\u4e2d\u306e\u30d7\u30ed\u30bb\u30b9\u3092\u4ed6\u3067\u7f6e\u304d\u63db\u3048\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u5b9f\u969b\u306eOS\u3067\u306f\u3001exec\u306e\u5b9f\u88c5\u306f\u305d\u308c\u4ee5\u4e0a\u306b\u8907\u96d1\u3060\u3002
\n\u305d\u308c\u3089\u306f\u3001\u30b7\u30a7\u30eb\u30b9\u30af\u30ea\u30d7\u30c8\u3084\uff08\u6b21\u306eexercise\u3092\u53c2\u7167\uff09\u3001\u3082\u3063\u3068\u8907\u96d1\u306aELF\u30d0\u30a4\u30ca\u30ea\u3084\u3001\u8907\u5408\u7684\u306a\u30d0\u30a4\u30ca\u30ea\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3092\u6271\u3046\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
\u5b9f\u969b\u306eOS\u306b\u304a\u3051\u308b\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u306e\u6982\u8981\u3067\u3059\u306d\u3002<\/p>\n
x86\u3067\u5b9f\u969b\u306e\u7269\u7406\u30e1\u30e2\u30ea\u91cf\u3092\u691c\u51fa\u3059\u308b\u6709\u540d\u306a\u65b9\u6cd5\u304c3\u3064\u3042\u308b\u3088\u3046\u3067\u3059\u3002
\n\u8a73\u7d30\u306f\u4e0d\u660e\u3067\u3059\u304c\u30011\u3064\u76ee\u306f\u5168\u8d70\u67fb\u3059\u308b\u65b9\u6cd5\u30012\u3064\u76ee\u306f\u30e1\u30e2\u30ea\u30c1\u30c3\u30d7\u306e\u60c5\u5831\u3092\u8aad\u53d6\u308b\u65b9\u6cd5\uff08\u591a\u5206\uff09\u30013\u3064\u76ee\u306fBIOS\u304b\u3089\u8aad\u307f\u53d6\u308b\u65b9\u6cd5\u307f\u305f\u3044\u3067\u3059\u3002
\n\u3067BIOS\u304b\u3089\u8aad\u307f\u53d6\u308b\u306e\u306f\u591a\u5206\u3044\u308d\u3093\u306a\u5834\u5408\u304c\u3042\u3063\u3066\u96e3\u3057\u3044\u3093\u3067\u3057\u3087\u3046\u306d\u3002<\/p>\n
\u30af\u30cc\u30fc\u30b9\u3092\u898b\u308d\u306e\u6240\u306f\u3088\u304f\u5206\u304b\u308a\u307e\u305b\u3093\u3002
\n\u30af\u30cc\u30fc\u30b9\u306f\u51c4\u3044\u4eba\u306a\u306e\u3067\u3001\u5f7c\u306e\u8003\u3048\u51fa\u3057\u305f\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u304c\u4eca\u65e5\u3082\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u30a2\u30eb\u30b4\u30ea\u30ba\u30e0\u3068\u3057\u3066\u751f\u304b\u3055\u308c\u3066\u308b\u3068\u304b\u3001\u5f53\u6642\u30e1\u30e2\u30ea\u5272\u308a\u5f53\u3066\u306b\u95a2\u3059\u308b\u8b70\u8ad6\u3092\u76db\u3093\u306b\u884c\u306a\u3063\u305f\u308a\u3068\u304b\u666e\u901a\u306b\u3042\u308a\u305d\u3046\u3067\u3059\u304c\u3001\u5177\u4f53\u7684\u306a\u4f8b\u306f\u77e5\u308a\u307e\u305b\u3093\u3002
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