| II、实模式下的初始化
实模式下的初始化,主要是指从内核引导成功后，到进入保护模式之前系统所做的一些处理。在内核源码中对应的程序是
/Arch/i386/boot/setup.S；以下部分主要是针对此文件进行的分析。这部分的分析主要是要弄懂它的处理流程和INITSEG(9000:0000)段参数表的建立，此参数表包含了很多硬件参数，这些都是以后进行保护模式下初始化，以及核心建立的基础。
1. 几个其它相关文件：
<1> /Arch/i386/boot/bootsect.S
<2> /include/linux/config.h
<3> /include/asm/boot.h
<4> /include/ asm/segment.h
<5> /include/linux/version.h
<6> /include/linux/compile.h
2. 实模式下的初始化过程分析：
INITSEG(9000:0000)段参数表：（参见Include/linux/tty.h）
| 参数名
|
偏移量(段址均为0x9000)
|
长度Byte
|
参考文件
|
| PARAM_CURSOR_POS
|
0x0000
|
2
|
Arch/i386/boot/video.S
|
| extended
mem Size |
0x0002
|
2
|
Arch/i386/boot/setup.S
|
| PARAM_VIDEO_PAGE
|
0x0004
|
2
|
Arch/i386/boot/video.S
|
| PARAM_VIDEO_MODE
|
0x0006
|
1
|
Arch/i386/boot/video.S
|
| PARAM_VIDEO_COLS
|
0x0007
|
1
|
Arch/i386/boot/video.S
|
| 没用
|
0x0008
|
2
|
Include/linux/tty.h
|
| PARAM_VIDEO_EGA_BX
|
0x000a
|
2
|
Arch/i386/boot/video.S
|
| 没用
|
0x000c
|
2
|
Include/linux/tty.h
|
| PARAM_VIDEO_LINES
|
0x000e
|
1
|
Arch/i386/boot/video.S
|
| PARAM_HAVE_VGA
|
0x000f
|
1
|
Arch/i386/boot/video.S
|
| PARAM_FONT_POINTS
|
0x0010
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_WIDTH
|
0x0012
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_HEIGHT
|
0x0014
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_DEPTH
|
0x0016
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_BASE
|
0x0018
|
4
|
Arch/i386/boot/video.S
|
| PARAM_LFB_SIZE
|
0x001c
|
4
|
Arch/i386/boot/video.S
|
| 暂未用①
|
0x0020
|
4
|
Include/linux/tty.h
|
| PARAM_LFB_LINELENGTH
|
0x0024
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_COLORS
|
0x0026
|
6
|
Arch/i386/boot/video.S
|
| 暂未用②
|
0x002c
|
2
|
Arch/i386/boot/video.S
|
| PARAM_VESAPM_SEG
|
0x002e
|
2
|
Arch/i386/boot/video.S
|
| PARAM_VESAPM_OFF
|
0x0030
|
2
|
Arch/i386/boot/video.S
|
| PARAM_LFB_PAGES
|
0x0032
|
2
|
Arch/i386/boot/video.S
|
| 保留
|
0x0034--0x003f
|
|
Include/linux/tty.h
|
| APM
BIOS Version③ |
0x0040
|
2
|
Arch/i386/boot/setup.S
|
| BIOS
code segment |
0x0042
|
2
|
Arch/i386/boot/setup.S
|
| BIOS
entry offset |
0x0044
|
4
|
Arch/i386/boot/setup.S
|
| BIOS
16 bit code seg |
0x0048
|
2
|
Arch/i386/boot/setup.S
|
| BIOS
data segment |
0x004a
|
2
|
Arch/i386/boot/setup.S
|
| 支持32位标志④
|
0x004c
|
2
|
Arch/i386/boot/setup.S
|
| BIOS
code seg length |
0x004e
|
4
|
Arch/i386/boot/setup.S
|
| BIOS
data seg length |
0x0052
|
2
|
Arch/i386/boot/setup.S
|
| hd0
参数 |
0x0080
|
16
|
Arch/i386/boot/setup.S
|
| hd0
参数 |
0x0090
|
16
|
Arch/i386/boot/setup.S
|
| PS/2
device 标志⑤ |
0x01ff
|
1
|
Arch/i386/boot/setup.S
|
* 注： ① Include/linux/tty.h ： CL_MAGIC and CL_OFFSET
here
Include/linux/tty.h ：
unsigned char rsvd_size; /* 0x2c */
unsigned char rsvd_pos; /* 0x2d */
③ 0表示没有APM BIOS
④ 0x0002置位表示支持32位模式
⑤ 0表示没有，0x0aa表示有鼠标器
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