global smp_go
; master boot record for application processors
;[org 0x7000]
smp_go:
[bits 16]

    cli				;switch off interrupts!
    lgdt [gdt_descriptor]	;load descriptor table!

    ;switch on 32-bit protected mode
    mov eax, cr0
    or eax,0x1 
    mov cr0, eax

    jmp 0x8:init_pm

[bits 32]


LLOCK:	    dd 0

init_pm:

    mov ax, 0x10
    mov ds, ax
    mov ss, ax
    mov es, ax
    mov fs, ax
    mov gs, ax

    mov ebp, 0x8000
    mov esp, ebp

    call boot_32_pm	    ;continue booting in 32-bit protected mode

boot_32_pm:

    mov eax, 1		 ; semaphore	
    xchg eax, [LLOCK]
    cmp eax,1
    hlt
    je $
    jmp $ ; loop forever here

    call [0x8010] ;kernel_ap			        ;jump into our Kernel!
    jmp $ ; should never be reached


gdt_start:

gdt_null:   ;null descriptor (2 x 4 bytes)
    dd 0x0
    dd 0x0

gdt_code:
    ; flags:
    ; present: 1 / privilege: 00 / type: 1
    ; code: 1 / conforming: 0 / readable: 1 / accessed: 0
    ; granularity: 1 / 16-bit default: 1 / 64-bit seg: 0 / AVL: 0
    dw 0xffff	    ;limit
    dw 0x0	    ;base
    db 0x0	    ;base
    db 10011010b    ;flags
    db 11001111b    ;flags & seg.limit
    db 0x0	    ;base

gdt_data:
    ; flags:
    ; code: 0 / expand down: 0 / writable: 1 / accessed: 0
    dw 0xffff
    dw 0x0
    db 0x0
    db 10010010b
    db 11001111b
    db 0x0

gdt_end:

gdt_descriptor:
    dw gdt_end-gdt_start-1
    dd gdt_start

CODE_SEG equ gdt_code - gdt_start
DATA_SEG equ gdt_data - gdt_start