return in pmode from a v86 task

org 7c00h

use16

cli
lgdt[gdt]
mov eax,cr4
or al,1
mov cr4,eax
mov eax,cr0
or al,1
mov cr0,eax
jmp gdt_code-gdt_table:pmode

vm86:
mov ax,0e41h
mov bx,7
int 10h
mov ax,gdt_data-gdt_table
mov gs,ax
mov fs,ax
mov ds,ax
mov es,ax
mov ss,ax
push ss
push esp
pushf
push gdt_code-gdt_table
push return
iretd
jmp $

use32

pmode:
mov ax,gdt_data-gdt_table
mov gs,ax
mov fs,ax
mov ds,ax
mov es,ax
mov ss,ax
mov esp,9fffch
mov ax,18h
ltr ax
push 0
push 0
push 0
push 0
push 0
push 0fffeh
push 20000h
push 0
push vm86
iret
jmp $
return:
mov dword[0b8000h],41h
mov dword[0b8000h+1],7
jmp $

gdt:
dw gdt_end-gdt_table-1
dd gdt_table

gdt_table:
dq 0

gdt_code:
dw 0ffffh
dw 0
db 0
db 9ah
db 0cfh
db 0

gdt_data:
dw 0ffffh
dw 0
db 0
db 92h
db 0cfh
db 0

gdt_tss:
dw 0ffffh
dw 0
db 0
db 89h
db 8fh
db 0

gdt_end:

times 510-($-$$) db 0
dw 0aa55h