virtual8086:
    push eax
    push ebx
    push ecx
    push edx
    push esi
    push edi
    push ebp

%define .oldEBP    esp
%define .oldEDI    esp+4
%define .oldESI    esp+8
%define .oldEDX    esp+12
%define .oldECX    esp+16
%define .oldEBX    esp+20
%define .oldEAX    esp+24
%define .errorCode esp+28
%define .oldEIP    esp+32
%define .oldCS     esp+36
%define .oldEFLAGS esp+40
%define .oldESP    esp+44
%define .oldSS     esp+48
%define .oldES     esp+52
%define .oldDS     esp+56
%define .oldFS     esp+60
%define .oldGS     esp+64

    mov eax,0x10;KERNEL_DATA_SEG
    mov ds,eax
    mov es,eax

    movzx eax,word [.oldCS]
    movzx ebx,word [.oldEIP]
    shl eax,4
    add ebx,eax                  ;ebx = address of instruction that caused GPF
    mov dl,[ebx]                 ;dl = first byte of instruction that caused GPF

    cmp dl, 0xcd                 ;Was it a software interrupt?
    jz .vm8086_monitor_int       ; yes
    cmp dl, 0x9c                 ;Was it a PUSHF?
    jz .vm8086_monitor_pushf     ; yes

    ;Need to do an error message and abort (can't continue running
    ;  virtual8086 code because we can't handle whatever caused the
    ;  GPF).

.abortV86:
;    sti
cli
.die:
    hlt
    jmp .die


.vm8086_monitor_int:
    movzx eax,word [.oldSS]
    movzx edi,word [.oldESP]
    shl eax,4
    add edi,eax                  ;edi = address of interrupted code's SS:SP
    mov ax,[.oldCS]
    sub edi,2
    mov [edi],ax                  ;Put original CS on interrupted code's stack
    mov ax,[.oldEIP]
    sub edi,2
add ax, 2

    mov [edi],ax                  ;Put original IP on interrupted code's stack
    sub word [.oldESP],4         ;Decrease original SP
    movzx eax,byte [ebx+1]       ;eax = interrupt number
    movzx ecx,word [eax*4]       ;ecx = IP for interrupt
    movzx eax,word [eax*4+2]     ;eax = CS for interrupt
    mov [.oldEIP],ecx            ;Set new return EIP
    mov [.oldCS],eax             ;Set new return CS
    or dword [.oldEFLAGS],(1<<9) ;Set IF flag in original EFLAGS
btc dword [.oldEFLAGS], 9
    jmp .vm8086_monitor_return   ;Return to the requested interrupt handler
                                 ; (which will return to the original code)

.vm8086_monitor_pushf:
    jmp .abortV86           ;Until this code is written...


.vm8086_monitor_return:
    pop ebp
    pop edi
    pop esi
    pop edx
    pop ecx
    pop ebx
    pop eax
    add esp,4               ;Skip over error code
    iret