我有以下引导加载程序代码，它似乎在硬盘上运行得很好：
[bits 16]
[org 0x7c00]
bootld_start:
KERNEL_OFFSET equ 0x2000
xor ax, ax ; Explicitly set ES = DS = 0
mov ds, ax
mov es, ax
mov bx, 0x8C00 ; Set SS:SP to 0x8C00:0x0000 . The stack will exist
; between 0x8C00:0x0000 and 0x8C00:0xFFFF
mov ss, bx
mov sp, ax
mov [BOOT_DRIVE], dl
mov bx, boot_msg
call print_string
mov dl, [BOOT_DRIVE]
call disk_load
jmp pm_setup
jmp $
BOOT_DRIVE:
db 0
disk_load:
mov si, dap
mov ah, 0x42
int 0x13
;cmp al, 4
;jne disk_error_132
ret
dap:
db 0x10 ; Size of DAP
db 0
; You can only read 46 sectors into memory between 0x2000 and
; 0x7C00. Don't read anymore or we overwrite the bootloader we are
; executing from. (0x7c00-0x2000)/512 = 46
dw 46 ; Number of sectors to read
dw KERNEL_OFFSET ; Offset
dw 0 ; Segment
dd 1
dd 0
disk_error_132:
mov bx, disk_error_132_msg
call print_string
jmp $
disk_error_132_msg:
db 'Error! Error! Something is VERY wrong! (0x132)', 0
gdt_start:
gdt_null:
dd 0x0
dd 0x0
gdt_code:
dw 0xffff
dw 0x0
db 0x0
db 10011010b
db 11001111b
db 0x0
gdt_data:
dw 0xffff
dw 0x0
db 0x0
db 10010010b
db 11001111b
db 0x0
gdt_end:
gdt_descriptor:
dw gdt_end - gdt_start
dd gdt_start
CODE_SEG equ gdt_code - gdt_start
DATA_SEG equ gdt_data - gdt_start
boot_msg:
db 'OS is booting files... ', 0
done_msg:
db 'Done! ', 0
%include "boot/print_string.asm"
pm_setup:
mov bx, done_msg
call print_string
mov ax, 0
mov ss, ax
mov sp, 0xFFFC
mov ax, 0
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
cli
lgdt[gdt_descriptor]
mov eax, cr0
or eax, 0x1
mov cr0, eax
jmp CODE_SEG:b32
[bits 32]
VIDEO_MEMORY equ 0xb8000
WHITE_ON_BLACK equ 0x0f
print32:
pusha
mov edx, VIDEO_MEMORY
.loop:
mov al, [ebx]
mov ah, WHITE_ON_BLACK
cmp al, 0
je .done
mov [edx], ax
add ebx, 1
add edx, 2
jmp .loop
.done:
popa
ret
b32:
mov ax, DATA_SEG
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
; Place stack below EBDA in lower memory
mov ebp, 0x9c000
mov esp, ebp
mov ebx, pmode_msg
call print32
call KERNEL_OFFSET
jmp $
pmode_msg:
db 'Protected mode enabled!', 0
kernel:
mov ebx, pmode_msg
call print32
jmp $
pmode_tst:
db 'Testing...'
times 510-($-$$) db 0
db 0x55
db 0xAA
问题是当我使用以下命令将其转换为 ISO 时：
mkdir iso
mkdir iso/boot
cp image.flp iso/boot/boot
xorriso -as mkisofs -R -J -c boot/bootcat \
-b boot/boot -no-emul-boot -boot-load-size 4 \
-o image.iso iso
...它因三重故障而失败。当我使用 运行它时qemu-system-i386 -boot d -cdrom os-image.iso -m 512 -d int -no-reboot -no-shutdown，它会输出（不包括无用的 SMM 异常）：
check_exception old: 0xffffffff new 0xd
0: v=0d e=0000 i=0 cpl=0 IP=0008:0000000000006616
pc=0000000000006616
SP=0010:000000000009bff8 env->regs[R_EAX]=0000000000000000
EAX=00000000 EBX=00007d72 ECX=00000000 EDX=000000e0
ESI=00007cb0 EDI=00000010 EBP=0009c000 ESP=0009bff8
EIP=00006616 EFL=00000083 [--S---C] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
CS =0008 00000000 ffffffff 00cf9a00 DPL=0 CS32 [-R-]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT= 00007c73 00000018
IDT= 00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
DR6=00000000ffff0ff0 DR7=0000000000000400
CCS=000000e0 CCD=000001b3 CCO=ADDB
EFER=0000000000000000
check_exception old: 0xd new 0xd
1: v=08 e=0000 i=0 cpl=0 IP=0008:0000000000006616 pc=0000000000006616 SP=0010:000000000009bff8 env- >regs[R_EAX]=0000000000000000
EAX=00000000 EBX=00007d72 ECX=00000000 EDX=000000e0
ESI=00007cb0 EDI=00000010 EBP=0009c000 ESP=0009bff8
EIP=00006616 EFL=00000083 [--S---C] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
CS =0008 00000000 ffffffff 00cf9a00 DPL=0 CS32 [-R-]
SS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
DS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
FS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
GS =0010 00000000 ffffffff 00cf9300 DPL=0 DS [-WA]
LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT= 00007c73 00000018
IDT= 00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
DR6=00000000ffff0ff0 DR7=0000000000000400
CCS=000000e0 CCD=000001b3 CCO=ADDB
EFER=0000000000000000
check_exception old: 0x8 new 0xd
这意味着我得到了 0x0d（一般保护故障），然后是 0x08（双重故障），然后是三重故障。为什么会这样？
编辑：我已将命令更改为：
xorriso -as mkisofs -R -J -c boot/bootcat -b boot/boot.flp -o nmos.iso nmos.flp
但我现在收到以下错误：
xorriso : FAILURE : Cannot find in ISO image: -boot_image ... bin_path='/boot/boot.flp'
xorriso : NOTE : -return_with SORRY 32 triggered by problem severity FAILURE
有谁知道这意味着什么？
编辑2：
我已将代码更改为使用 ah=0x02 读取，如下所示：
mov bx, KERNEL_OFFSET
mov ah, 0x02
mov al, 46
mov ch, 0x00
mov dh, 0x00
mov cl, 0x02
mov dl, [BOOT_DRIVE]
int 0x13
但它仍然是三重故障。为什么？