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Update boot.s #9

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5e054c5
Update boot.s
qingshu-yu Feb 13, 2022
97d93d8
Update util.s
qingshu-yu Feb 13, 2022
87a9703
Update config.h
qingshu-yu Feb 13, 2022
762330b
Update init.h
qingshu-yu Feb 13, 2022
f146708
Update init.c
qingshu-yu Feb 13, 2022
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42 changes: 28 additions & 14 deletions boot/x86/boot.s
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Original file line number Diff line number Diff line change
Expand Up @@ -7,38 +7,48 @@ org 7c00h
_start:
%define init_base 0x0500
bits 16
mov ax, cs
mov ds, ax
mov ss, ax
; mov sp, 0
; 寄存器复位
mov ax, cs
mov ds, ax
mov ss, ax
; mov sp, 0

; 屏蔽所有外部中断
cli

; 清除屏幕
call cls


; 初始化光标
mov dx,0x0000
call set_cursor


; 打印boot字符串
mov si,boot
call print_string


; 读取磁盘
mov bx,init_base
call load_init


; 读取成功
mov si,load_init_success
call print_string

;;跳转loader地址
; 跳转到loader
jmp init_base

jmp $

;;磁盘读取到内存 es:bx 地址
; int 13h ah=02h 读取磁盘扇区 al=读入的扇区数 ch=磁道号的低8位 cl=扇区号1~63(bit 0~5)磁道号,(柱面号)的高2位(bit 6~7,只对硬盘有效) dh=磁头号 dl=驱动器号 es:bx=>数据缓冲区
; 根目录占用空间 = 14(详细请查看fat12相关信息)
load_init:
mov ah,0x02 ;读取功能
mov al,0x0e ;读取几个扇区
mov cl,0x02 ;0x01 boot sector, 0x02 is first sector
mov ah,0x02
mov al,0x0e
mov cl,0x02
mov ch,0x00
mov dh,0x00
mov dl,0x00 ;软盘0
mov dl,0x00
int 0x13
jc disk_error
jmp dend
Expand All @@ -50,9 +60,13 @@ dend:

%include "boot/x86/util.s"

; 字符串定义(0x0a,0x0d,0表结束符)
boot db "boot duck",0x0a,0x0d,0
disk_erro db "read boot disk erro",0x0a,0x0d,0
load_init_success db "load init success",0x0a,0x0d,0

; 补齐至512
times 510-($-$$) db 0

; boot结束标志
dw 0xaa55
2 changes: 2 additions & 0 deletions boot/x86/config.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
#ifndef BOOT/X86/CONFIG_H
#define BOOT/X86/CONFIG_H
// 内核块数(512)
#define KERNEL_BLOCK_SIZE 93
// 内核大小
#define KERNEL_SIZE 95064
#endif
72 changes: 61 additions & 11 deletions boot/x86/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
********************************************************************/
#include "init.h"

// 标识16位代码
asm(".code16gcc\n");
asm("cli\n");
#if defined(__WIN32__)
Expand All @@ -18,10 +19,13 @@ boot_info_t boot_data;
u8 kernel_stack[1024]; // 1k
u8 kernel_stack_top[0];

// 清屏,设置光标
void cls() {
// clear screen
// int 10h ah=06h表滚动窗口 AL=滚动的列数，若为0则实现清空屏幕功能
asm("int $0x10\n" : : "a"(0x0600));
// set cursor pos
// int 10h ah=02h表设定光标位置 DH=游标的列数 DL=游标的行数 BH=页码
asm("int $0x10\n" : : "a"(0x0200), "b"(0x0000), "d"(0x00));
// __asm__ __volatile__("int $0x10" : : "a"(0x0013));
}
Expand All @@ -38,7 +42,10 @@ void getch() {
"int $0x16\n");
}

void print_char(char s) { asm("int $0x10\n" : : "a"(s | 0x0e00), "b"(0x0007)); }
void print_char(char s) {
// int 10h ah=0eh al=打印字符 bh＝页码 bl=前景色
asm("int $0x10\n" : : "a"(s | 0x0e00), "b"(0x0007));
}

void itoa(char* buf, int base, int d) {
char* p = buf;
Expand All @@ -65,6 +72,7 @@ void itoa(char* buf, int base, int d) {
*p = 0;

/* Reverse BUF. */
// 字符顺序调整
p1 = buf;
p2 = p - 1;
while (p1 < p2) {
Expand All @@ -77,15 +85,18 @@ void itoa(char* buf, int base, int d) {
}

void printf(const char* format, ...) {
// 取得参数列表基址
char** arg = (char**)&format;
int c;
char buf[20];

arg++;

while ((c = *format++) != 0) {
// 为可输出字符
if (c != '%')
print_char(c);
// 分析格式
else {
char* p;

Expand Down Expand Up @@ -115,6 +126,7 @@ void printf(const char* format, ...) {
}
}

// 初始化boot_info信息
void init_boot_info() {
boot_info = &boot_data;
boot_info->version = BOOT_VERSION;
Expand All @@ -127,8 +139,11 @@ void init_boot_info() {
}

void init_disk() {
// 固定值
boot_info->disk.hpc = 2;
// 每柱面扇区数
boot_info->disk.spt = 18;
// 1.44m软盘
boot_info->disk.type = 1; // 1.44m floppy flat lba
}

Expand Down Expand Up @@ -165,6 +180,8 @@ u8 disk_read(u16 disk, u16 head, u16 cylinder, u16 sector, u16 number, u32 addr,
u16 dx = (head << 8) | disk;
u16 ax = (0x02 << 8) | number;
u16 erro;
// int 13h ah=02h 读取磁盘扇区 al=读入的扇区数 ch=磁道号的低8位 cl=扇区号1~63(bit 0~5)磁道号,(柱面号)的高2位(bit 6~7,只对硬盘有效) dh=磁头号 dl=驱动器号 es:bx=>数据缓冲区
// 调用结束 如果访问出错则CF被置1，AX存放错误信息 如果访问成功则CF被清零，AH存放状态，AL存放读入扇区数
asm volatile(
"pushw %%es \n"
"movw %w[seg], %%es \n"
Expand All @@ -181,6 +198,7 @@ u8 disk_read(u16 disk, u16 head, u16 cylinder, u16 sector, u16 number, u32 addr,
}

u8 disk_read_lba(u32 lba, u32 addr, u8* status) {
// 将LBA格式转换为CHS格式（Cylinder/Head/Sector，柱面/磁头/扇区）
u32 cylinder = lba / boot_info->disk.spt / boot_info->disk.hpc;
u32 head = (lba / boot_info->disk.spt) % boot_info->disk.hpc;
u32 sector = (lba % boot_info->disk.spt) + 1;
Expand All @@ -200,9 +218,13 @@ u8 disk_read_lba(u32 lba, u32 addr, u8* status) {
void read_kernel() {
u8 status = 0;
print_string("");
// 柱面号
u32 cylinder = 0;
// 磁头号
u32 head = 0;
// 扇区号
u32 sector = 0xc;
// LBA（Logical Block Address，逻辑块寻址）格式磁盘扇区号
u32 lba = 0x00;
u8 ret = 0;
if (boot_info->disk.type == 1) {
Expand All @@ -213,6 +235,7 @@ void read_kernel() {
#ifdef KERNEL_MOVE
u32 addr = boot_info->kernel_origin_base;
#else
// 内核将要被读取到的位置
u32 addr = boot_info->kernel_base;
#endif
for (int i = 0; i < KERNEL_BLOCK_SIZE * 2; i++) {
Expand Down Expand Up @@ -258,21 +281,26 @@ int memory_prob() {
memory_info_t* ptr = boot_info->memory;
boot_info->total_memory = 0;
for (; count < MAX_MEMORY_BLOCK;) {
// int 15h ax=E820h表获取内存信息 ebx第一次调用必须为0 ecx表内存结构体的大小(字节) edx=0534D4150h es:di为内存信息结构体
// 调用结束 eax=0534D4150h(如果不为0534D4150h，则硬件故障) ebx=无需关心值为什么，只需再次传入即可获取下一个内存信息描述符 ecx=被填充的字符数
asm("int $0x15"
: "=a"(signature), "=c"(bytes), "=b"(id)
: "a"(0xE820), "b"(id), "c"(24), "d"(0x534D4150), "D"(ptr));
// 硬件故障
if (signature != 0x534D4150) {
return -1;
} else if (bytes > 20 && (ptr->extended & 0x0001) == 0) {
} else if (bytes > 20 && (ptr->extended & 0x0001) == 0) { // 检查CF，是否发生错误
} else {
boot_info->total_memory += ptr->length;
ptr++;
count++;
}
// ebx为0表示为最后一个内存区域
if (id == 0) {
break;
}
}
// 记录内存区域数量
boot_info->memory_number = count;
return count;
}
Expand Down Expand Up @@ -332,28 +360,40 @@ void init_gdt() {

void init_cpu() {
// enable cr0
// 置位CR0寄存器的第0位来开启保护模式
unsigned long cr0 = read_cr0();
write_cr0(cr0 | 1);
}

void init_boot() {
// 初始化boot_info信息
init_boot_info();

// 清屏,设置光标
cls();
printf("boot info addr %x\n\r", boot_info);


// 初始化gdt
init_gdt();


// 初始化显示模式信息
print_string("init display\n\r");
init_display();


// 初始化内存信息
print_string("init memory\n\r");
init_memory();


// 初始化软盘
init_disk();


// 读取内核
read_kernel();

// 初始化cpu
init_cpu();


// 栈设置
asm volatile(
"movl %0, %%esp\n"
"mov %%esp,%%ebp\n"
Expand Down Expand Up @@ -381,6 +421,7 @@ void* load_kernel() {
#endif

Elf32_Ehdr* elf_header = (Elf32_Ehdr*)elf;
// 判断魔数,如果是elf文件,则加载elf文件，找到内核程序入口
if (elf_header->e_ident[0] == ELFMAG0 || elf_header->e_ident[1] == ELFMAG1) {
// printf("header: ");
// for (int x = 0; x < 16; x++) {
Expand All @@ -398,11 +439,12 @@ void* load_kernel() {
load_elf(elf_header);
return elf_header->e_entry;
} else {
// printf("bin kernel\n\r");
return boot_info->kernel_base;
// printf("bin kernel\n\r");
return boot_info->kernel_base; // 如果不是elf文件，程序入口即内核地址
}
}

// 从s2复制n个字符到s1
void* memmove32(void* s1, const void* s2, u32 n) {
u32 *dest, *src;
int i;
Expand All @@ -413,6 +455,7 @@ void* memmove32(void* s1, const void* s2, u32 n) {
}
}

// 处理elf文件
void load_elf(Elf32_Ehdr* elf_header) {
// printf("e_phnum:%d\n\r", elf_header->e_phnum);
u16* elf = elf_header;
Expand All @@ -427,6 +470,7 @@ void load_elf(Elf32_Ehdr* elf_header) {
// phdr[i].p_vaddr, phdr[i].p_paddr, "", phdr[i].p_filesz,
// phdr[i].p_memsz);
break;
// 提取出来可加载程序段
case PT_LOAD: {
// printf(" %s %x %x %x %s %x %x \r\n", "LOAD", phdr[i].p_offset,
// phdr[i].p_vaddr, phdr[i].p_paddr, "", phdr[i].p_filesz,
Expand Down Expand Up @@ -507,17 +551,23 @@ void load_elf(Elf32_Ehdr* elf_header) {
// start kernel
void start_kernel() {
asm volatile("cli\n");
// 寄存器置位
asm volatile("movl %0, %%ss" : : "r"(GDT_ENTRY_32BIT_DS * GDT_SIZE));
asm volatile("movl %0, %%ds" : : "r"(GDT_ENTRY_32BIT_DS * GDT_SIZE));
asm volatile("movl %0, %%es" : : "r"(GDT_ENTRY_32BIT_DS * GDT_SIZE));
asm volatile("movl %0, %%gs" : : "r"(GDT_ENTRY_32BIT_DS * GDT_SIZE));
asm volatile("movl %0, %%fs" : : "r"(GDT_ENTRY_32BIT_FS * GDT_SIZE));
// print_string("load kernel\n\r");
// 获取内核入口
boot_info->kernel_entry = load_kernel();
entry start = boot_info->kernel_entry;

// 参数
int argc = 0;
char** argv = 0;
char* envp[10];
envp[0] = boot_info;

// 转至内核
start(argc, argv, envp);
}
}
9 changes: 7 additions & 2 deletions boot/x86/init.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,16 @@
#include "config.h"


#define KERNEL_MOVE
#define KERNEL_MOVE
// 扇区大小
#define READ_BLOCK_SIZE 512
// 内核地址
#define KERNEL_BASE 0x100000
// 内核原地址
#define KERNEL_ORIGIN_BASE 0x10000
// 页表地址
#define PDT_BASE 0x9000
// 版本
#define BOOT_VERSION 0x01


Expand All @@ -29,4 +34,4 @@ void* load_kernel();
void init_memory();
void init_kernel();

#endif
#endif
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