切换至保护模式时QEMU异常重启的技术求助

我在实模式下完成操作后尝试切换到保护模式，但出现异常情况。实模式中我制作了简单欢迎界面，要求用户输入姓名，之后本该切换至保护模式，但实际表现为：按下Enter键后，某个字符背景开始变化，随后我使用的QEMU模拟器重启并重新显示欢迎界面。

以下是相关代码：

section startUp vstart=0x7f00

; clearing the screen 
    mov ah,0x00
    mov al,0x03   
    int 0x10
; disabling the cursor
    mov ah,0x01
    mov ch,0x3f 
    int 0x10
; using Bios to print character
    mov ah,0x0e
    mov al,'C'
    mov cx,0x01
    int 0x10
; printing a string 
    mov ax,msg
    mov bx,0x00
    mov cl,0x0f
    mov dx,0x00
    call printMsg
; print warning 
    mov ax,warning
    mov bx,0x00
    mov cl,0x04
    mov dx,0x3a
    call printMsg
; print message
    mov ax,msg2
    mov bx,0x00
    mov cl,0x0f
    mov dx,0x0140
    call printMsg
; input 
    mov si,keypress
    mov bx,0x00
    call input



; switching to protected mode 
    cli           ; disabling interrupts 
    lgdt [GDT_Descriptor]     
    mov eax,cr0
    or eax,0x01
    mov cr0,eax   ; here we are in 32 bit protected mode

    jmp protectedMode









; printing a string function 
printMsg:
    pusha 

    ; ax ==> offset , bx ==> segment , dl ==> Line a0*lineNumber - 1, cl ==> color 

    mov es,bx
    
    mov bx,0xB000
    mov ds,bx 

    mov si,ax
    
    mov di,0x8000
    add di,dx

    mov byte[es:0x7e00],0x00 
    jmp loopThrough

    
    loopThrough:
        mov al,byte[es:si]
        mov byte[ds:di], al

        add di,0x01
        mov byte[ds:di],cl
        sub di,0x01

        add si,0x01

        mov bl,byte[es:si]
        cmp bl,0x00
            
        je quit

        add di,0x02
        jmp loopThrough
            
    quit :
        popa
        ret



; input function kjjj
input:
    pusha
    ; si ==> offset , bx ==> segment 
    mov di,si 
    mov es,bx 

    jmp loopinterupt


    loopinterupt :
        mov ah,0x00
        int 0x16

        cmp al,0x20

        je quitInput


        mov byte[es:si],al
        add si,0x01
        mov byte[es:si],0x00

        mov ax,di
        mov dx,0x172
        mov cl,0x0f
        call printMsg

        
        jmp loopinterupt

    quitInput :
        popa 
        ret




; Data


; Setting Up the GDT
GDT :

times 8 db 0x00

; base : 0x100000   ; Limit : 0x00700
dw 0x0700  ; limit 1 
dw 0x0000  ; base 1 
db 0x10    ; base 2
db 0x9a    ; access Byte 
db 0xc0    ; limit + flags
db 0x00d    ; base 3


; base : 0x800000  ; limit : 0x00700 
dw 0x0700  ; limit 1 
dw 0x0000  ; base 1 
db 0x80    ; base 2
db 0x96    ; access Byte 
db 0xc0    ; limit + flags
db 0x00    ; base 3

GDT_Descriptor :
dw GDT_Descriptor - GDT - 1
dd GDT 




msg db 'Welcome to the OS fdffdfgd',0x00
msg2 db 'Please write your name : ',0x00
keypress db 'K',0x00
warning db ""


[bits 32]
protectedMode:
    jmp $


times 1024-($-$$) db 0 

代码在执行到jmp protectedMode语句前均正常运行。

内容的提问来源于stack exchange，提问作者Djebbar Abderrahmene