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来自「linux 0.11中文版 有注释」· HTML 代码 · 共 48 行
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<title>include/linux/head.h</title>
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<a name='TOP'><h2><a href='../mains.html'>root</a>/<a href='../files/99.html'>include</a>/<a href='../files/101.html'>linux</a>/head.h</h2>
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<h2><a href='../J/33.html' title='Multiple included from 4 places.'>INCLUDED FROM</a></h2>
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<h2>DEFINITIONS</h2>
This source file includes following definitions.
<ol>
<li><a href='#L8' title='Defined at 8.'>desc_table</a>
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<a name='L1'><font color='darkred'>#ifndef</font> <a href='../S/33.html#L2' title='Defined at 2 in include/linux/head.h.'>_HEAD_H</a>
<a name='L2'><font color='darkred'>#define</font> <a href='../S/33.html#L1' title='Refered from 1 in include/linux/head.h.'>_HEAD_H</a>
<a name='L3'>
<a name='L4'><b>typedef</b> <b>struct</b> desc_struct
<a name='L5'><font color='red'>{</font> <i><font color='green'>// 定义了段描述符的数据结构。该结构仅说明每个描述</font></i>
<a name='L6'> <b>unsigned</b> <b>long</b> a, b; <i><font color='green'>// 符是由8 个字节构成,每个描述符表共有256 项。</font></i>
<a name='L7'><font color='red'>}</font>
<a name='L8'><a href='../S/33.html#L11' title='Refered from 11 in include/linux/head.h.'>desc_table</a>[256];
<a name='L9'>
<a name='L10'><b>extern</b> <b>unsigned</b> <b>long</b> pg_dir[1024]; <i><font color='green'>// 内存页目录数组。每个目录项为4 字节。从物理地址0 开始。</font></i>
<a name='L11'><b>extern</b> <a href='../S/33.html#L8' title='Defined at 8 in include/linux/head.h.'>desc_table</a> idt, gdt; <i><font color='green'>// 中断描述符表,全局描述符表。</font></i>
<a name='L12'>
<a name='L13'><font color='darkred'>#define</font> GDT_NUL 0 <i><font color='green'>// 全局描述符表的第0 项,不用。</font></i>
<a name='L14'><font color='darkred'>#define</font> GDT_CODE 1 <i><font color='green'>// 第1 项,是内核代码段描述符项。</font></i>
<a name='L15'><font color='darkred'>#define</font> GDT_DATA 2 <i><font color='green'>// 第2 项,是内核数据段描述符项。</font></i>
<a name='L16'><font color='darkred'>#define</font> GDT_TMP 3 <i><font color='green'>// 第3 项,系统段描述符,Linux 没有使用。</font></i>
<a name='L17'>
<a name='L18'><font color='darkred'>#define</font> LDT_NUL 0 <i><font color='green'>// 每个局部描述符表的第0 项,不用。</font></i>
<a name='L19'><font color='darkred'>#define</font> LDT_CODE 1 <i><font color='green'>// 第1 项,是用户程序代码段描述符项。</font></i>
<a name='L20'><font color='darkred'>#define</font> LDT_DATA 2 <i><font color='green'>// 第2 项,是用户程序数据段描述符项。</font></i>
<a name='L21'>
<a name='L22'><font color='darkred'>#endif</font>
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