assembly - 系统在 QEMU 上启动，但在真实硬件上出现恐慌（重新启动）

Question

我在引导加载程序中从 CBS 切换到 LBA，在 ata_lba_read 之后以 32 位模式加载内核 在此之前，我总是用 QEMU 测试我的系统，它在那里工作（并且工作）完美。现在我决定尝试在真实硬件上启动系统。它打印一条引导消息并永远重新启动（内核未加载）我搜索了一段时间的答案，但只有那些已经在我的引导加载程序中实现。

这是引导加载程序代码：

ORG 7C00h
[BITS 16]

CODE_SEG equ GDT_CODE - GDT_START
DATA_SEG equ GDT_DATA - GDT_START

jmp short start
nop

;FAT16 Header
OEM_Identifier db 'FAT16OEM'
BytesPerSector dw 0x200
SectorsPerCluster db 0x80
ReservedSectors dw 200
FATCopies db 0x02
RootDirEntries dw 0x40
NumberOfSectors dw 0
MediaType db 0xF8
SectorsPerFAT dw 0x100
SectorsPerTrack dw 0x20
NumberOfHeads dw 0x40
HiddenSectors dd 0x00
SectorsBig dd 0x773594

;Extended BPB
DriveNumber db 0x80
WinNTBit db 0x00
Signature db 0x29
VolumeID dd 0xD105
VolumeIDString db 'MYSTOS_BOOT'
SystemIDString db 'MOSFAT16'

start:
    jmp 0x0:load

load:
    cli
    mov ax, 0x00
    mov ds, ax
    mov es, ax
    mov ss, ax
    mov sp, 0x00
    sti

    mov cx, bootmsg
    call print
    mov cx, newline
    call print
    mov ax, 0xFFFF
    mov cx, 0x2000
    call sleep

.load_protected:
    cli
    lgdt[GDT_DESCRIPTOR]
    mov eax, cr0
    or eax, 0x1
    mov cr0, eax
    jmp CODE_SEG:load32

print:
    push si
    push bx
    push ax
    mov si, cx
    mov bx, 0
    print_loop:
        lodsb
        cmp al, 0
        jz finish_print
        call PrintChar
        jmp print_loop
    finish_print:
        pop ax
        pop bx
        pop si
        ret

PrintChar:
    mov ah, 0Eh
    int 10h
    ret

sleep:
    push ax
    push cx
    sleep_loop:
        cmp cx, 0
        jz dec_ax
        dec cx
        jmp sleep_loop
    dec_ax:
        cmp ax, 0
        jz finish_sleep
        dec ax
        pop cx
        push cx
        jmp sleep_loop
    finish_sleep:
        pop cx
        pop ax
        ret


GDT_START:

GDT_NULL: ;64 bits of zeros
    dd 0x0 
    dd 0x0

; offset 0x8
GDT_CODE:     ;CS SHOULD POINT TO THIS
    dw 0xFFFF ;Segment limit first 0-15 bits
    dw 0      ;Base first 0-15 bits
    db 0      ;Base 16-23 bits
    db 0x9a   ;Access byte
    db 11001111b ;High and low 4 bit flags
    db 0      ;Base 24-31 bits

; offset 0x10
GDT_DATA:     ;DS, SS, ES, FS, GS
    dw 0xFFFF ;Segment limit first 0-15 bits
    dw 0      ;Base first 0-15 bits
    db 0      ;Base 16-23 bits
    db 0x92   ;Access byte
    db 11001111b ;High and low 4 bit flags
    db 0      ;Base 24-31 bits

GDT_END:

GDT_DESCRIPTOR:
    dw GDT_END - GDT_START - 1
    dd GDT_START


[BITS 32]

load32:
    mov eax, 1
    mov ecx, 128
    mov edi, 0x0100000
    call ata_lba_read
    jmp CODE_SEG:0x0100000

ata_lba_read:
    mov ebx, eax ;Backup the LBA
    ;Send the highest 8 bits of the LBA to harddisk controller
    shr eax, 24 ;Shift 24 bits so eax now contain only the highest 8 bits of the LBA
    or eax, 0xE0 ;Select the master drive
    mov dx, 0x1F6
    out dx, al ;Send
    ;Send the total sectors to read
    mov eax, ecx
    mov dx, 0x1F2
    out dx, al
    ;Send more bits of the LBA
    mov eax, ebx ;Restore LBA
    mov dx, 0x1F3
    out dx, al
    ;Send more bits of the LBA
    mov eax, ebx ;Restore LBA
    mov dx, 0x1F4
    shr eax, 8 ;Shift 8 bits that were sent
    out dx, al
    ;Send upper 16 bits of the LBA
    mov eax, ebx ;Restore LBA
    mov dx, 0x1F5
    shr eax, 16 ;Shift 16 bits
    out dx, al
    ;Finished sending
    mov dx, 0x1F7
    mov al, 0x20
    out dx, al
    ;Read all sectors
    .next_sector:
        push ecx
    ;Checking the need to read
    .try_again:
        mov dx, 0x1F7
        in al, dx
        test al, 8
        jz .try_again
    ;We need to read 256 words at a time
        mov ecx, 256
        mov dx, 0x1F0
        rep insw
        pop ecx
        loop .next_sector
    ;End of reading
        ret


bootmsg db 'www.https://stackoverflow.com/', 0
newline db 0Ah, 0Dh, 0
times 510-($-$$) db 0
dw 0xAA55

UPD：32 位打印例程代码（基于 0xB8000 的 VGA 显存）将我的工作 C 打印功能转换为汇编之一。引导加载程序停止并阻止在 QEMU 中加载内核

makechar32: ;eax - chr, edx - color
    shl edx, 8
    or edx, eax
    mov eax, edx
    ret

putchar32: ;eax - chr, edx - color, ebx - x, ecx - y
    call makechar32
    mov esi, 0xB8000
    ;video_mem_saddr + y*80 + x
    add esi, ebx
    mov ebx, eax
    mov eax, 80
    mul ecx
    mov ecx, eax
    add esi, ecx
    mov [esi], ebx
    ret

printchar32: ;eax - chr, edx - color
    pushad
    mov ebx, [col]
    mov ecx, [row]
    call putchar32
    inc ebx
    cmp ebx, 80
    jge newrow
    newcol:
        inc ebx
        mov [col], ebx
        popad
        ret
    newrow:
        xor ebx, ebx
        mov [col], ebx
        inc ecx
        mov [row], ecx
        popad
        ret

print32: ;ecx - *str
    pushad
    mov esi, ecx
    print32_loop:
        lodsb
        cmp eax, 0
        jz finish_print32
        mov edx, 7
        call printchar32
        jmp print32_loop
    finish_print32:
        popad
        ret

标签： assemblyx86nasmbootloaderosdev