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	; Switch to 32-bit mode
	lgdt [GDTR32]						; Load a 32-bit GDT
	xor eax, eax						; Clear the segment registers
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax
	mov rax, cr0
	btc rax, 31						; Clear PG (Bit 31)
	mov cr0, rax

BITS 32
	; Call Pure64
	jmp 8:0x8000						; 32-bit jump to set CS

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	xor eax, eax						; Clear the segment registers
	mov ss, ax

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	mov rax, cr0
	btc rax, 31						; Clear PG (Bit 31)
	mov cr0, rax

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switch_to_protected_mode   Proc far
    push eax
    push ebx
    push ecx
    push edx
    pushf
;
    mov ebx,eax
    cli
;
    mov eax,cr0
    and eax,7FFFFFFFh
    mov cr0,eax
;
    mov ecx,IA32_EFER
    rdmsr
    and eax,0FFFFFEFFh   
    wrmsr
;
    mov cr3,ebx
;
    mov eax,cr0
    or eax,80000000h
    mov cr0,eax
;
    lidt fword ptr cs:prot_idt_size
;
    popf
    pop edx
    pop ecx
    pop ebx
    pop eax    
    ret
switch_to_protected_mode  Endp

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align 16
GDTR64:					; Global Descriptors Table Register
dw gdt64_end - gdt64 - 1		; limit of GDT (size minus one)
dq gdt64				; linear address of GDT

align 16
gdt64:
dq 0x0000000000000000
dq 0x0040980000000000			; D(22), P(15), S(12), Type(11)
dq 0x0000900000000000			; P(15), S(12)
gdt64_end:

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	; Stop interrupts
	cli

	; Switch to 64-bit compatibility mode
	lgdt [GDTR64]
	mov eax, 8
	push rax
	lea rax, [compatmode]
	push rax
	call far [rsp]	

BITS 32
compatmode:
	; Switch to 32-bit mode
	lgdt [GDTR32]						; Load a 32-bit GDT
	mov eax, cr0
	btc eax, 31						; Clear PG (Bit 31)
	mov cr0, eax

	; Call Pure64
	jmp 8:0x8000						; 32-bit jump to set CS

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void Cpu::LoadGdt()
{
    const mtl::GdtPtr gdtPtr{sizeof(m_gdt) - 1, m_gdt};
    mtl::x86_lgdt(gdtPtr);

    asm volatile("pushq %0\n"
                 "pushq $1f\n"
                 "lretq\n"
                 "1:\n"
                 :
                 : "i"(Selector::KernelCode)
                 : "memory");

    asm volatile("movl %0, %%ds\n"
                 "movl %0, %%es\n"
                 "movl %1, %%fs\n"
                 "movl %1, %%gs\n"
                 "movl %0, %%ss\n"
                 :
                 : "r"(Selector::KernelData), "r"(Selector::Null)
                 : "memory");
}

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dq 0x0040980000000000			; D(22), P(15), S(12), Type(11)
dq 0x0000900000000000			; P(15), S(12)

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	mov eax, 8
	push rax

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	lea rax, [compatmode]
	push rax

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	call far [rsp]

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	jmp 8:0x8000						; 32-bit jump to set CS

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	; Stop interrupts
	cli

	; Build a 32-bit memory table
	mov rdi, 0x200000
	mov rax, 0x00000083
	mov rcx, 1024
again:
	stosd
	add rax, 0x400000
	dec rcx
	cmp rcx, 0
	jne again	

	; Load the custom GDT
	lgdt [gdtr]

	; Switch to compatibility mode
	mov rax, SYS32_CODE_SEL					; Compatibility mode
	push rax
	lea rax, [compatmode]
	push rax
	retfq

BITS 32
compatmode:

	; Set the segment registers
	mov eax, SYS32_DATA_SEL
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax

	; Deactivate IA-32e mode by clearing CR0.PG
	mov eax, cr0
	btc eax, 31						; Clear PG (Bit 31)
	mov cr0, eax

	; Load CR3
	mov eax, 0x200000
	mov cr3, eax

	; Disable IA-32e mode by setting IA32_EFER.LME = 0
	mov ecx, 0xC0000080					; EFER MSR number
	rdmsr							; Read EFER
	and eax, 0xFFFFFEFF 					; Clear LME (Bit 8)
	wrmsr							; Write EFER

	mov eax, 0x00000010					; Set PSE (Bit 4)
	mov cr4, eax

	; Enable legacy paged-protected mode by setting CR0.PG
	mov eax, 0x00000001					; Set PM (Bit 0)
	mov cr0, eax

	jmp SYS32_CODE_SEL:0x8000				; 32-bit jump to set CS

....

align 16
gdtr:					; Global Descriptors Table Register
dw gdt_end - gdt - 1			; limit of GDT (size minus one)
dq gdt					; linear address of GDT

align 16
gdt:
SYS64_NULL_SEL equ $-gdt		; Null Segment
dq 0x0000000000000000
SYS32_CODE_SEL equ $-gdt		; 32-bit code descriptor
dq 0x00CF9A000000FFFF			; 55 Granularity 4KiB, 54 Size 32bit, 47 Present, 44 Code/Data, 43 Executable, 41 Readable
SYS32_DATA_SEL equ $-gdt		; 32-bit data descriptor
dq 0x00CF92000000FFFF			; 55 Granularity 4KiB, 54 Size 32bit, 47 Present, 44 Code/Data, 41 Writeable
SYS64_CODE_SEL equ $-gdt		; 64-bit code segment, read/execute, nonconforming
dq 0x00209A0000000000			; 53 Long mode code, 47 Present, 44 Code/Data, 43 Executable, 41 Readable
SYS64_DATA_SEL equ $-gdt		; 64-bit data segment, read/write, expand down
dq 0x0000920000000000			; 47 Present, 44 Code/Data, 41 Writable
gdt_end: