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[BITS 16]

jmp loadermain

GDTR:
GDTsize DW GDTEND - GDT - 1
GDTbase DD 500h

GDT:
NULLSELECTOR    EQU             $ - GDT
                DD 0x0
                DD 0x0

CODESELECTOR    EQU             $ - GDT          ; 4GB Flat Code at 0x0 with max 0xFFFFF limit
                DW              0FFFFh           ; Limit(2):0xFFFF
                DW              0h               ; Base(3)
                DB              0h               ; Base(2)
                DB              09Ah             ; Type: present,ring0,code,exec/read/accessed (10011000)
                DB              0CFh             ; Limit(1):0xF | Flags:4Kb inc,32bit (11001111)
                DB              0h               ; Base(1)

DATASELECTOR    EQU             $ - GDT          ; 4GB Flat Data at 0x0 with max 0xFFFFF limit
                DW              0FFFFh           ; Limit(2):0xFFFF
                DW              0h               ; Base(3)
                DB              0h               ; Base(2)
                DB              092h             ; Type: present,ring0,data/stack,read/write (10010010)
                DB              0CFh             ; Limit(1):0xF | Flags:4Kb inc,32bit (11001111)
                DB              0h               ; Base(1)
GDTEND:

loadermain:
    mov ax, cs
    mov ds, ax
    mov es, ax
    mov fs, ax

    cli
    mov ax, 1D0h
    mov ss, ax
    mov sp, 0200h

    call EnableA20

    sti

lMoveGDT:
    xor ax, ax
    mov ds, ax
    mov es, ax
    mov si, GDT
    mov di, [GDTbase]
    mov cx, [GDTsize]
    cld
    rep movsb

lEnterPMode:
    cli
    mov eax, cr0
    or al, 1
    mov cr0, eax

    lgdt[GDTR]

    jmp CODESELECTOR:FlushPipeline  ;<-- crashes here...

[BITS 32]
FlushPipeline:
    mov eax, DATASELECTOR
    mov ds, eax
    mov es, eax
    mov fs, eax
    mov gs, eax
    mov ss, eax
    mov esp, 0ffffh

    jmp $
    cli
    hlt