Trampoline.asm

;==============================================================================
;= Digos Operating v 0.0.1                                                    =
;=                                                                            =
;= Startup code for AP´s                                                      =
;=                                                                            =
;= by Rodrigo Fagner                                                          =
;=                                                                            =
;= Sao Jose do Rio Preto - SP 10/10/2015 08:39                                =
;==============================================================================

SECTION .text
BITS 16

_entry:

JMP     ap_boot
ALIGN 4
GDTPointer		dd 0xA1A2A3A4          ; + 1
IDTPointer		dd 0x02020202          ; + 2
StackPointer		dd 0x03030303          ; + 3
StackTest		dd 0xBA000001          ; + 4
APCPUBooted		dd 0xBABBBCBD          ; + 5

ALIGN 4
ap_boot:
	cli
	cld

	mov ax, cs
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax

	mov EAX, StackTest
	mov EBX, [EAX]
	mov ESP, EBX

	MOV EAX, APCPUBooted
	MOV [EAX], DWORD 0xA1B2C3D4

	mov 	EAX, GDTPointer ; Loaded from smp.c
	lgdt	[EAX]		; load GDT into GDTR

	mov	EAX, IDTPointer ; Loaded from smp.c
	lidt	[EAX]		; load IDT into IDTR

;===============================
;=  Enable PMODE	       =
;===============================

	mov		eax, cr0	; set bit 0 in CR0-go to pmode
	or		eax, 1
	mov		cr0, eax

	; Just small delay...
	nop
	nop
	nop
	nop
	nop
	nop
	nop

;===============================
;=  Jump Far    	       =
;===============================

	jmp	0x08:.Stage3

BITS 32

.Stage3:
	CLI
	CLD

;===============================
;=  Set registers	       =
;===============================

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

	mov eax, StackPointer
	call [eax]

.halt: ; Just to make shure in some case...

	jmp .halt