基于scheme写的os
提前安装 bochs
./configure --with-sdl --enable-disasm --enable-all-optimizations --enable-readline --disable-debugger-gui --enable-x86-debugger --enable-a20-pin --enable-fast-function-calls --enable-debugger
编译
mkdir build
make
make run
boot.ss 加载loader到内存中，跳转到init
init.ss 加载内核到内存中，进入保护模式，跳转到内核
kernel.ss 内核文件
INT 10h
-
设置光标位置 AH=02H BH=页码，DH=列，DL=行
-
清除屏幕 AH=06H AL=滚动的行（0=清除，被用于CH，CL，DH，DL）， BH=背景颜色和前景颜色，BH=43H，意义为背景颜色为红色，前景颜色为青色。请参考BIOS颜色属性。 CH=高行数，CL=左列数，DH=低行数，DL=右列数
颜色显示
二进制数 颜色 例子 二进制数 颜色 例子
0000 黑色 black 1000 灰色 gray
0001 蓝色 blue 1001 淡蓝色 light blue
0010 绿色 green 1010 淡绿色 light green
0011 青色 cyan 1000 淡青色 light cyan
0100 红色 red 1100 淡红色 light red
0101 紫红色 magenta 1101 淡紫红色 light magenta
0110 棕色 brown 1110 黄色 yellow
0111 银色 light gray 1111 白色 white
INT 13h
- 复位 AH 00h DL Drive (bit 7 set means reset both hard and floppy disks)
DL = 00h 1st floppy disk ( "drive A:" )
DL = 01h 2nd floppy disk ( "drive B:" )
DL = 02h 3rd floppy disk ( "drive B:" )
. . .
DL = 7Fh 128th floppy disk)
DL = 80h 1st hard disk
DL = 81h 2nd hard disk
DL = 82h 3rd hard disk
. . .
DL = E0h CD/DVD[citation needed], or 97th hard disk
. . .
DL = FFh 128th hard disk
- 读取一个扇区 AH=02h: Read Sectors From Drive
AH 02h
AL Sectors To Read Count
CH Cylinder
CL Sector
DH Head
DL Drive
ES:BX Buffer Address Pointer
Results
CF Set On Error, Clear If No Error
AH Return Code
AL Actual Sectors Read Count
GDT（Global Descriptor Table，全局描述符表） LDT (Local Descriptor Table，局部描述符表)
GDT的每个表项，抽象地可以看成包含四个字段的数据结构：基地址（Base），大小（Limit），标志（Flag），访问信息（Access Byte）。
GDT
1st Double word:
Bits Function Description
0-15 Limit 0:15 First 16 bits in the segment limiter
16-31 Base 0:15 First 16 bits in the base address
2nd Double word:
Bits Function Description
0-7 Base 16:23 Bits 16-23 in the base address
8-12 Type Segment type and attributes
13-14 Privilege Level 0 = Highest privilege (OS), 3 = Lowest privilege (User applications)
15 Present flag Set to 1 if segment is present
16-19 Limit 16:19 Bits 16-19 in the segment limiter
20-22 Attributes Different attributes, depending on the segment type
23 Granularity Used together with the limiter, to determine the size of the segment
24-31 Base 24:31 The last 24-31 bits in the base address
The GDT Descriptor
Bits Function Description
0-15 Limit Size of GDT in bytes
16-47 Address GDT's memory address
无分页模式
线性地址等于物理地址
CR0.PG = 0
32bit模式
CR0.PG = 1 and CR4.PAE = 0
0-11: 页内偏移
12-21: 页表 (Page Table)
22-31: 页表目录表（Page Table Directory
PAE模式
CR0.PG = 1, CR4.PAE = 1, and IA32_EFER.LME = 0
0-11：页内偏移
12-20：页表（Page Table） PT PTE 512个
21-29：页表目录表（Page Table Directory） PTD PDE 512个
30-31：页目录指针表（Page Directory Pointer Table） PDPT PDPTE 4个
CR3=>31:30
PDPTE=>29:21
PDE=> 20:12
内存地址
0x0500 init
0x4000 page entry
0x7c00 boot
0x8000 kernel
TSS 任务状态段
x86 Structure
offset 0 - 15 16 - 31
0x00 LINK reserved
0x04 ESP0
0x08 SS0 reserved
0x0C ESP1
0x10 SS1 reserved
0x14 ESP2
0x18 SS2 reserved
0x1C CR3
0x20 EIP
0x24 EFLAGS
0x28 EAX
0x2C ECX
0x30 EDX
0x34 EBX
0x38 ESP
0x3C EBP
0x40 ESI
0x44 EDI
0x48 ES reserved
0x4C CS reserved
0x50 SS reserved
0x54 DS reserved
0x58 FS reserved
0x5C GS reserved
0x60 LDTR reserved
0x64 reserved IOPB offset
save esp ,eip restore esp ,eip
https://en.wikipedia.org/wiki/INT_10H
https://en.wikipedia.org/wiki/INT_13H
https://stanislavs.org/helppc/int_13-1.html
https://baike.baidu.com/item/INT10H/22788179?fr=aladdin
https://wiki.osdev.org/GDT_Tutorial
http://www.osdever.net/tutorials/view/the-world-of-protected-mode
https://files.osdev.org/mirrors/geezer/os/pm.htm
https://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-3a-part-1-manual.html
https://wiki.osdev.org/Task_State_Segment
https://wiki.osdev.org/Memory_Map_(x86)
http://www.uruk.org/orig-grub/mem64mb.html
https://wiki.osdev.org/Detecting_Memory_(x86)
https://zh.wikipedia.org/wiki/%E5%85%A8%E5%B1%80%E6%8F%8F%E8%BF%B0%E7%AC%A6%E8%A1%A8