所以，我使用Bochs来运行我的引导装载程序和https://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf第4.1章。
我试图通过直接写入视频内存来打印到BIOS控制台，但当我运行Bochs时，我看不到打印的字符串。该代码实际上与PDF上的代码相同。我错过了什么？有没有一个博克斯设置我忘记了或PDF没有告诉我的东西？
下面是包含函数的汇编文件

;
; A simple collection of string routines for 32-bit protected mode.
;
[bits 32]
VIDEO_MEMORY equ 0xB8000
WHITE_ON_BLACK equ 0x0f         ; Color mode for the text to be written

PrintString:    ; Assume ebx holds memory address of string.
    ; edx will hold start of video memory
    ; Recall that each character written will take up 2 bytes of video memory
    ; So any particular row or column on the screen will have mem location = 0xb80000
    ; + 2 * (80r + c)

    ; The way this code is written, its always writing starting from the start of the
    ; video memory at 0xb8000, the top left of the screen, replacing everything there.

    pusha
    mov edx, VIDEO_MEMORY

    PrintLoop:
        mov al, [ebx]            ; Only ebx can be used to index
        mov ah, WHITE_ON_BLACK

        cmp al, 0
        je ExitRoutine

        mov [edx], ax

        inc ebx
        add edx, 2

        jmp PrintLoop

    ExitRoutine:
        popa
        ret

下面是我实际的 Boot 逻辑。

;
; A simple boot sector program that loops forever.
;

[bits 32]
[org 0x7c00]

mov ebx, welcome_msg
call PrintString

jmp $

%include "string_utils.s"

welcome_msg db 'WELCOME TO BASICOS OMFG!', 0
goodbye_msg db 'Goodbye! Thanks for using my BasicOS!', 0

times 510 -( $ - $$ ) db 0

dw 0xaa55