操作系统编写。奇怪的错误

我正在编写我的操作系统。一切似乎都进展顺利（甚至可能太多了）。问题是控制权在读取磁盘扇区后立即转移到引导加载程序的第二部分。这怎么可能？

• boot1.asm：

[bits 16]
[org 0x7c00]
    jmp boot

BOOT2_OFFSET    equ 0x1000

boot:
    mov [BOOT_DRIVE], dl

    mov bx, MSG_BOOT1
    call print
    call print_nl

    call load_boot2

    jmp $

load_boot2:
    mov bx, MSG_BOOT2_LOAD
    call print
    call print_nl

    mov bx, BOOT2_OFFSET
    mov dh, 16
    mov dl, [BOOT_DRIVE]
    call disk_load

    jmp $

%include "disk.asm"
%include "print.asm"

BOOT_DRIVE      db 0
MSG_BOOT1       db "Loading in BOOT1...", 0
MSG_BOOT2_LOAD  db "Loading BOOT2.bin...", 0

times 510 - ($ - $$) db 0
dw 0xaa55

• disk.asm：

; load 'dh' sectors from drive 'dl' into ES:BX
disk_load:
    pusha
    push dx

    mov ah, 0x02
    mov al, dh
    mov cl, 0x02
    mov ch, 0x00
    mov dh, 0x00

    int 0x13
    jc disk_error
    jnc disk_success

    pop dx
    cmp al, dh
    jne sectors_error
    popa
    ret

disk_success:
    mov bx, DISK_SUCCESS
    call print
    call print_nl
    ret

disk_error:
    mov bx, DISK_ERR
    call print
    call print_nl
    jmp $

sectors_error:
    mov bx, SECT_ERR
    call print
    jmp $

DISK_ERR:       db "Disk read error!", 0
SECT_ERR:       db "Incorrect number of sectors read!", 0
DISK_SUCCESS:   db "Disk read success!", 0

• print.asm：

print:
    pusha

start:
    mov al, [bx]
    cmp al, 0 
    je done
    add bx, 1
    jmp start

done:
    popa
    ret

print_nl:
    pusha
    
    mov ah, 0x0e
    mov al, 0x0a
    int 0x10
    mov al, 0x0d
    int 0x10
    
    popa
    ret

• boot2.asm

[bits 16]
[org 0x1000]
    jmp boot2

boot2:
    mov bx, MSG_BOOT2
    call print
    call print_nl

    jmp $

%include "print.asm"

MSG_BOOT2       db "Loading in BOOT2...", 0

• 结论qemu：

• 我是这样收集的：

  1. nasm boot1.asm -f bin -o boot1.bin
  2. nasm boot2.asm -f bin -o boot2.bin
  3. cat boot1.bin boot2.bin > os.bin
  4. qemu-system-i386 -fda os.bin