{"id":46791,"date":"2023-12-11T15:09:50","date_gmt":"2023-12-11T07:09:50","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=46791"},"modified":"2023-12-11T15:09:50","modified_gmt":"2023-12-11T07:09:50","slug":"%e8%af%b7%e4%bd%a0%e8%af%b4%e4%b8%80%e8%af%b4%e6%93%8d%e4%bd%9c%e7%b3%bb%e7%bb%9f%e4%b8%ad%e7%9a%84%e9%a1%b5%e8%a1%a8%e5%af%bb%e5%9d%80-3","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/12\/11\/%e8%af%b7%e4%bd%a0%e8%af%b4%e4%b8%80%e8%af%b4%e6%93%8d%e4%bd%9c%e7%b3%bb%e7%bb%9f%e4%b8%ad%e7%9a%84%e9%a1%b5%e8%a1%a8%e5%af%bb%e5%9d%80-3\/","title":{"rendered":"\u8bf7\u4f60\u8bf4\u4e00\u8bf4\u64cd\u4f5c\u7cfb\u7edf\u4e2d\u7684\u9875\u8868\u5bfb\u5740"},"content":{"rendered":"<p>&#8220;`&#8221;                    \u53c2\u8003\u56de\u7b54\uff1a<\/p>\n<p>\u9875\u5f0f\u5185\u5b58\u7ba1\u7406\uff0c\u5185\u5b58\u5206\u6210\u56fa\u5b9a\u957f\u5ea6\u7684\u4e00\u4e2a\u4e2a\u9875\u7247\u3002\u64cd\u4f5c\u7cfb\u7edf\u4e3a\u6bcf\u4e00\u4e2a\u8fdb\u7a0b\u7ef4\u62a4\u4e86\u4e00\u4e2a\u4ece\u865a\u62df\u5730\u5740\u5230\u7269\u7406\u5730\u5740\u7684\u6620\u5c04\u5173\u7cfb\u7684\u6570\u636e\u7ed3\u6784\uff0c\u53eb\u9875\u8868\uff0c\u9875\u8868\u7684\u5185\u5bb9\u5c31\u662f\u8be5\u8fdb\u7a0b\u7684\u865a\u62df\u5730\u5740\u5230\u7269\u7406\u5730\u5740\u7684\u4e00\u4e2a\u6620\u5c04\u3002\u9875\u8868\u4e2d\u7684\u6bcf\u4e00\u9879\u90fd\u8bb0\u5f55\u4e86\u8fd9\u4e2a\u9875\u7684\u57fa\u5730\u5740\u3002\u901a\u8fc7\u9875\u8868\uff0c\u7531\u903b\u8f91\u5730\u5740\u7684\u9ad8\u4f4d\u90e8\u5206\u5148\u627e\u5230\u903b\u8f91\u5730\u5740\u5bf9\u5e94\u7684\u9875\u57fa\u5730\u5740\uff0c\u518d\u7531\u9875\u57fa\u5730\u5740\u504f\u79fb\u4e00\u5b9a\u957f\u5ea6\u5c31\u5f97\u5230\u6700\u540e\u7684\u7269\u7406\u5730\u5740\uff0c\u504f\u79fb\u7684\u957f\u5ea6\u7531\u903b\u8f91\u5730\u5740\u7684\u4f4e\u4f4d\u90e8\u5206\u51b3\u5b9a\u3002\u4e00\u822c\u60c5\u51b5\u4e0b\uff0c\u8fd9\u4e2a\u8fc7\u7a0b\u90fd\u53ef\u4ee5\u7531\u786c\u4ef6\u5b8c\u6210\uff0c\u6240\u4ee5\u6548\u7387\u8fd8\u662f\u6bd4\u8f83\u9ad8\u7684\u3002\u9875\u5f0f\u5185\u5b58\u7ba1\u7406\u7684\u4f18\u70b9\u5c31\u662f\u6bd4\u8f83\u7075\u6d3b\uff0c\u5185\u5b58\u7ba1\u7406\u4ee5\u8f83\u5c0f\u7684\u9875\u4e3a\u5355\u4f4d\uff0c\u65b9\u4fbf\u5185\u5b58\u6362\u5165\u6362\u51fa\u548c\u6269\u5145\u5730\u5740\u7a7a\u95f4\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>Linux\u6700\u521d\u7684\u4e24\u7ea7\u9875\u8868\u673a\u5236\uff1a<\/p>\n<p>\u4e24\u7ea7\u5206\u9875\u673a\u5236\u5c0632\u4f4d\u7684\u865a\u62df\u7a7a\u95f4\u5206\u6210\u4e09\u6bb5\uff0c\u4f4e\u5341\u4e8c\u4f4d\u8868\u793a\u9875\u5185\u504f\u79fb\uff0c\u9ad820\u5206\u6210\u4e24\u6bb5\u5206\u522b\u8868\u793a\u4e24\u7ea7\u9875\u8868\u7684\u504f\u79fb\u3002<\/p>\n<ul>\n<li>PGD(Page Global Directory): \u6700\u9ad810\u4f4d\uff0c\u5168\u5c40\u9875\u76ee\u5f55\u8868\u7d22\u5f15<\/p>\n<\/li>\n<li>\n<p>PTE(Page Table Entry)\uff1a\u4e2d\u95f410\u4f4d\uff0c\u9875\u8868\u5165\u53e3\u7d22\u5f15<\/p>\n<\/li>\n<\/ul>\n<p>\u5f53\u5728\u8fdb\u884c\u5730\u5740\u8f6c\u6362\u65f6\uff0c\u7ed3\u5408\u5728CR3\u5bc4\u5b58\u5668\u4e2d\u5b58\u653e\u7684\u9875\u76ee\u5f55(page directory, PGD)\u7684\u8fd9\u4e00\u9875\u7684\u7269\u7406\u5730\u5740\uff0c\u518d\u52a0\u4e0a\u4ece\u865a\u62df\u5730\u5740\u4e2d\u62bd\u51fa\u9ad810\u4f4d\u53eb\u505a\u9875\u76ee\u5f55\u8868\u9879(\u5185\u6838\u4e5f\u79f0\u8fd9\u4e3apgd)\u7684\u90e8\u5206\u4f5c\u4e3a\u504f\u79fb, \u5373\u5b9a\u4f4d\u5230\u53ef\u4ee5\u63cf\u8ff0\u8be5\u5730\u5740\u7684pgd\uff1b\u4ece\u8be5pgd\u4e2d\u53ef\u4ee5\u83b7\u53d6\u53ef\u4ee5\u63cf\u8ff0\u8be5\u5730\u5740\u7684\u9875\u8868\u7684\u7269\u7406\u5730\u5740\uff0c\u518d\u52a0\u4e0a\u4ece\u865a\u62df\u5730\u5740\u4e2d\u62bd\u53d6\u4e2d\u95f410\u4f4d\u4f5c\u4e3a\u504f\u79fb, \u5373\u5b9a\u4f4d\u5230\u53ef\u4ee5\u63cf\u8ff0\u8be5\u5730\u5740\u7684pte\uff1b\u5728\u8fd9\u4e2apte\u4e2d\u5373\u53ef\u83b7\u53d6\u8be5\u5730\u5740\u5bf9\u5e94\u7684\u9875\u7684\u7269\u7406\u5730\u5740, \u52a0\u4e0a\u4ece\u865a\u62df\u5730\u5740\u4e2d\u62bd\u53d6\u7684\u6700\u540e12\u4f4d\uff0c\u5373\u5f62\u6210\u8be5\u9875\u7684\u9875\u5185\u504f\u79fb, \u5373\u53ef\u6700\u7ec8\u5b8c\u6210\u4ece\u865a\u62df\u5730\u5740\u5230\u7269\u7406\u5730\u5740\u7684\u8f6c\u6362\u3002\u4ece\u4e0a\u8ff0\u8fc7\u7a0b\u4e2d\uff0c\u53ef\u4ee5\u770b\u51fa\uff0c\u5bf9\u865a\u62df\u5730\u5740\u7684\u5206\u7ea7\u89e3\u6790\u8fc7\u7a0b\uff0c\u5b9e\u9645\u4e0a\u5c31\u662f\u4e0d\u65ad\u6df1\u5165\u9875\u8868\u5c42\u6b21\uff0c\u9010\u6e10\u5b9a\u4f4d\u5230\u6700\u7ec8\u5730\u5740\u7684\u8fc7\u7a0b\uff0c\u6240\u4ee5\u8fd9\u4e00\u8fc7\u7a0b\u88ab\u53eb\u505apage talbe walk\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>Linux\u7684\u4e09\u7ea7\u9875\u8868\u673a\u5236\uff1a<\/p>\n<p>\u5f53X86\u5f15\u5165\u7269\u7406\u5730\u5740\u6269\u5c55(Pisycal Addrress Extension, PAE)\u540e\uff0c\u53ef\u4ee5\u652f\u6301\u5927\u4e8e4G\u7684\u7269\u7406\u5185\u5b58(36\u4f4d\uff09\uff0c\u4f46\u865a\u62df\u5730\u5740\u4f9d\u7136\u662f32\u4f4d\uff0c\u539f\u5148\u7684\u9875\u8868\u9879\u4e0d\u9002\u7528\uff0c\u5b83\u5b9e\u9645\u591a4 bytes\u88ab\u6269\u5145\u52308 bytes\uff0c\u8fd9\u610f\u5473\u7740\uff0c\u6bcf\u4e00\u9875\u73b0\u5728\u80fd\u5b58\u653e\u7684pte\u6570\u76ee\u4ece1024\u53d8\u6210512\u4e86(4k\/8)\u3002\u76f8\u5e94\u5730\uff0c\u9875\u8868\u5c42\u7ea7\u53d1\u751f\u4e86\u53d8\u5316\uff0cLinus\u65b0\u589e\u52a0\u4e86\u4e00\u4e2a\u5c42\u7ea7\uff0c\u53eb\u505a\u9875\u4e2d\u95f4\u76ee\u5f55(page middle directory, PMD), \u53d8\u6210\uff1a<\/p>\n<p>\u5b57\u6bb5      \u63cf\u8ff0            \u4f4d\u6570<\/p>\n<p>cr3      \u6307\u5411\u4e00\u4e2aPDPT      crs\u5bc4\u5b58\u5668\u5b58\u50a8<\/p>\n<p>PGD    \u6307\u5411PDPT\u4e2d4\u4e2a\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d31~30<\/p>\n<p>PMD    \u6307\u5411\u9875\u76ee\u5f55\u4e2d512\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d29~21<\/p>\n<p>PTE      \u6307\u5411\u9875\u8868\u4e2d512\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d20~12<\/p>\n<p>page offset  4KB\u9875\u4e2d\u7684\u504f\u79fb      \u4f4d11~0<\/p>\n<p>&nbsp;<\/p>\n<p>\u73b0\u5728\u5c31\u540c\u65f6\u5b58\u57282\u7ea7\u9875\u8868\u548c3\u7ea7\u9875\u8868\uff0c\u5728\u4ee3\u7801\u7ba1\u7406\u4e0a\u80af\u5b9a\u4e0d\u65b9\u4fbf\u3002\u5de7\u5999\u7684\u662f\uff0cLinux\u91c7\u53d6\u4e86\u4e00\u79cd\u62bd\u8c61\u65b9\u6cd5\uff1a\u6240\u6709\u67b6\u6784\u5168\u90e8\u4f7f\u75283\u7ea7\u9875\u8868: \u5373PGD -&gt; PMD -&gt; PTE\u3002\u90a3\u53ea\u4f7f\u75282\u7ea7\u9875\u8868(\u5982\u975ePAE\u7684X86)\u600e\u4e48\u529e\uff1f<\/p>\n<p>\u529e\u6cd5\u662f\u9488\u5bf9\u4f7f\u75282\u7ea7\u9875\u8868\u7684\u67b6\u6784\uff0c\u628aPMD\u62bd\u8c61\u6389\uff0c\u5373\u865a\u8bbe\u4e00\u4e2aPMD\u8868\u9879\u3002\u8fd9\u6837\u5728page table walk\u8fc7\u7a0b\u4e2d\uff0cPGD\u672c\u76f4\u63a5\u6307\u5411PTE\u7684\uff0c\u73b0\u5728\u4e0d\u4e86\uff0c\u6307\u5411\u4e00\u4e2a\u865a\u62df\u7684PMD\uff0c\u7136\u540e\u518d\u7531PMD\u6307\u5411PTE\u3002\u8fd9\u79cd\u62bd\u8c61\u4fdd\u6301\u4e86\u4ee3\u7801\u7ed3\u6784\u7684\u7edf\u4e00\u3002<\/p>\n<p>&nbsp;<\/p>\n<p>Linux\u7684\u56db\u7ea7\u9875\u8868\u673a\u5236\uff1a<\/p>\n<p>\u786c\u4ef6\u5728\u53d1\u5c55\uff0c3\u7ea7\u9875\u8868\u5f88\u5feb\u53c8\u6349\u895f\u89c1\u8098\u4e86\uff0c\u539f\u56e0\u662f64\u4f4dCPU\u51fa\u73b0\u4e86, \u6bd4\u5982X86_64\uff0c \u5b83\u7684\u786c\u4ef6\u662f\u5b9e\u5b9e\u5728\u5728\u652f\u63014\u7ea7\u9875\u8868\u7684\u3002\u5b83\u652f\u630148\u4f4d\u7684\u865a\u62df\u5730\u5740\u7a7a\u95f41\u3002\u5982\u4e0b\uff1a<\/p>\n<p>\u5b57\u6bb5      \u63cf\u8ff0            \u4f4d\u6570<\/p>\n<p>PML4    \u6307\u5411\u4e00\u4e2aPDPT      \u4f4d47~39<\/p>\n<p>PGD    \u6307\u5411PDPT\u4e2d4\u4e2a\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d38~30<\/p>\n<p>PMD    \u6307\u5411\u9875\u76ee\u5f55\u4e2d512\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d29~21<\/p>\n<p>PTE      \u6307\u5411\u9875\u8868\u4e2d512\u9879\u4e2d\u7684\u4e00\u4e2a  \u4f4d20~12<\/p>\n<p>page offset  4KB\u9875\u4e2d\u7684\u504f\u79fb      \u4f4d11~0<\/p>\n<p>&nbsp;<\/p>\n<p>Linux\u5185\u6838\u9488\u4e3a\u4f7f\u7528\u539f\u6765\u76843\u7ea7\u5217\u8868(PGD-&gt;PMD-&gt;PTE)\uff0c\u505a\u4e86\u6298\u8877\u3002\u5373\u91c7\u7528\u4e00\u4e2a\u552f\u4e00\u7684\uff0c\u5171\u4eab\u7684\u9876\u7ea7\u5c42\u6b21\uff0c\u53ebPML4\u3002\u8fd9\u4e2aPML4\u6ca1\u6709\u7f16\u7801\u5728\u5730\u5740\u4e2d\uff0c\u8fd9\u6837\u5c31\u80fd\u5957\u7528\u539f\u6765\u76843\u7ea7\u5217\u8868\u65b9\u6848\u4e86\u3002\u4e0d\u8fc7\u4ee3\u4ef7\u5c31\u662f\uff0c\u7531\u4e8e\u53ea\u6709\u552f\u4e00\u7684PML4, \u5bfb\u5740\u7a7a\u95f4\u88ab\u5c40\u9650\u5728(239=)512G, \u800c\u672c\u6765PML4\u6bb5\u67099\u4f4d, \u53ef\u4ee5\u652f\u6301512\u4e2aPML4\u8868\u9879\u7684\u3002\u73b0\u5728\u4e3a\u4e86\u4f7f\u75283\u7ea7\u5217\u8868\u65b9\u6848\uff0c\u53ea\u80fd\u9650\u5236\u4f7f\u7528\u4e00\u4e2a\uff0c 512G\u7684\u7a7a\u95f4\u5f88\u5feb\u5c31\u53c8\u4e0d\u591f\u7528\u4e86\uff0c\u89e3\u51b3\u65b9\u6848\u547c\u4e4b\u6b32\u51fa\u3002<\/p>\n<p>\u57282004\u5e7410\u6708\uff0c\u5f53\u65f6\u7684X86_64\u67b6\u6784\u4ee3\u7801\u7684\u7ef4\u62a4\u8005Andi Kleen\u63d0\u4ea4\u4e86\u4e00\u4e2a\u53eb\u505a4level page tables for Linux\u7684PATCH\u7cfb\u5217\uff0c\u4e3aLinux\u5185\u6838\u5e26\u6765\u4e864\u7ea7\u9875\u8868\u7684\u652f\u6301\u3002\u5728\u4ed6\u7684\u89e3\u51b3\u65b9\u6848\u4e2d\uff0c\u4e0d\u51fa\u610f\u6599\u5730\uff0c\u6309\u7167X86_64\u89c4\u8303\uff0c\u65b0\u589e\u4e86\u4e00\u4e2aPML4\u7684\u5c42\u7ea7, \u5728\u8fd9\u79cd\u89e3\u51b3\u65b9\u6848\u4e2d\uff0cX86_64\u62e5\u4e00\u4e2a\u6709512\u6761\u76ee\u7684PML4, 512\u6761\u76ee\u7684PGD, 512\u6761\u76ee\u7684PMD, 512\u6761\u76ee\u7684PTE\u3002\u5bf9\u4e8e\u4ecd\u4f7f\u75283\u7ea7\u76ee\u5f55\u7684\u67b6\u6784\u6765\u8bf4\uff0c\u5b83\u4eec\u4f9d\u7136\u62e5\u6709\u4e00\u4e2a\u865a\u62df\u7684PML4,\u76f8\u5173\u7684\u4ee3\u7801\u4f1a\u5728\u7f16\u8bd1\u65f6\u88ab\u4f18\u5316\u6389\u3002 \u8fd9\u6837\uff0c\u5c31\u628aLinux\u5185\u6838\u76843\u7ea7\u5217\u8868\u6269\u5145\u4e3a4\u7ea7\u5217\u8868\u3002\u8fd9\u7cfb\u5217PATCH\u5de5\u4f5c\u5f97\u4e0d\u9519\uff0c\u4e0d\u4e45\u88ab\u7eb3\u5165Andrew Morton\u7684-mm\u6811\u63a5\u53d7\u6d4b\u8bd5\u3002\u4e0d\u51fa\u610f\u5916\u7684\u8bdd\uff0c\u5b83\u5c06\u5728v2.6.11\u7248\u672c\u4e2d\u91ca\u51fa\u3002\u4f46\u662f\uff0c\u53e6\u4e00\u4e2a\u77e5\u540d\u5f00\u53d1\u8005Nick Piggin\u63d0\u51fa\u4e86\u4e00\u4e9b\u770b\u6cd5\uff0c\u4ed6\u8ba4\u4e3aAndi\u7684Patch\u5f88\u4e0d\u9519\uff0c\u4e0d\u8fc7\u4ed6\u8ba4\u4e3a\u6700\u597d\u8fd8\u662f\u628aPGD\u4f5c\u4e3a\u7b2c\u4e00\u7ea7\u76ee\u5f55\uff0c\u628a\u65b0\u589e\u52a0\u7684\u5c42\u6b21\u653e\u5728\u4e2d\u95f4\uff0c\u5e76\u7ed9\u51fa\u4e86\u4ed6\u81ea\u5df1\u7684Patch:alternate 4-level page tables patches\u3002Andi\u66f4\u60f3\u4fdd\u6301\u81ea\u5df1\u7684PATCH, \u4ed6\u8ba4\u4e3aNick\u4e0d\u8fc7\u662f\u73a9\u4e86\u6539\u540d\u7684\u6e38\u620f\uff0c\u800c\u4e14\u4ed6\u7684PATCH\u7ecf\u8fc7\u6d4b\u8bd5\u5f88\u7a33\u5b9a\uff0c\u5feb\u88ab\u5408\u5e76\u5230\u4e3b\u7ebf\u4e86\uff0c\u4e0d\u5b9c\u518d\u6298\u817e\u3002\u4e0d\u8fc7Linus\u5374\u8868\u8fbe\u4e86\u5bf9Nick Piggin\u7684\u652f\u6301\uff0c\u7406\u7531\u662fNick\u7684\u505a\u6cd5conceptually least intrusive\u3002\u6bd5\u7adf\u4f5c\u4e3aLinux\u7684\u625b\u628a\u5b50\uff0c\u7a33\u5b9a\u5bf9\u4e8eLinus\u6765\u8bf4\u610f\u4e49\u91cd\u5927\u3002\u6700\u7ec8\uff0c\u4e0d\u610f\u5916\u5730\uff0c\u6700\u540eNick Piggin\u7684PATCH\u5728v2.6.11\u7248\u672c\u4e2d\u88ab\u5408\u5e76\u5165\u4e3b\u7ebf\u3002\u5728\u8fd9\u79cd\u65b9\u6848\u4e2d\uff0c4\u7ea7\u9875\u8868\u5206\u522b\u662f\uff1aPGD -&gt; PUD -&gt; PMD -&gt; PTE\u3002<\/p>\n<pre><code>            \"```\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>&#8220;`&#8221; \u53c2\u8003\u56de\u7b54\uff1a \u9875\u5f0f\u5185\u5b58\u7ba1\u7406\uff0c\u5185\u5b58\u5206\u6210\u56fa\u5b9a\u957f\u5ea6\u7684\u4e00\u4e2a\u4e2a\u9875\u7247\u3002\u64cd\u4f5c\u7cfb\u7edf\u4e3a\u6bcf\u4e00\u4e2a\u8fdb\u7a0b\u7ef4 [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-46791","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/46791","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=46791"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/46791\/revisions"}],"predecessor-version":[{"id":46792,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/46791\/revisions\/46792"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=46791"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=46791"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=46791"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}