[SOS] Secteur de boot

[Chris]

Salut,
Je suis en train de faire un secteur de boot qui passe en mode protégé
mais j'ai des problèmes (reboot après 3 exceptions cf. Bochs output).
Est-ce que qqun pourrait me dire ce qui ne va pas ? Le problème survient
au jump vers l'OS. Je suis un peu pressé par le temps (projet à terminer
assez vite).

Merci d'avance.

Christian Vincenot


************************myboot.asm****************************** 

[ORG 7C00h] 
[BITS 16] 
;------------------DEFS--------------------------------------; 

BIOS_DROP equ 0x07C0 ; Where the BIOS dropped us 
KSTART equ 2 ; 
KSIZE equ 1 ; 
KSEG equ 1000h ; Where we'll throw the kernel 

;-----------------CODE---------------------------------------; 


;Set up our stack 
;mov ax, BIOS_DROP ; 
;mov ds, ax ;AX = DS = ES = BIOS_DROP 
;mov es, ax ; 
;mov ax, 0x8000 
;mov ss, ax ; let's set up our stack from 0x8000 
;mov sp, 0xf000 ; to 0xf000 

mov si,takeoff 
call bprint ; Greetings !! 

;Copy the kernel 
mov ax, 0x200 + KSIZE ; service: AH=0x2 (copy), AL=KERNEL_SIZE sectors 
;mov es, word [KSEG] 
push word KSEG ; ES <- KERNEL_SEG (copy destination) 
pop es ; 
xor bx, bx ; BX <- 0 (dunno if that has to be...) 
mov cx, KSTART ; CX <- KERNEL_START (copy source) 
xor dx, dx ; DX <- 0 
int 13h 
jnc done 

mov si, error ; error 
call bprint 
jmp $ 

done: 
mov si, success 
call bprint 

cli ; Disable interrupts 
xor ax, ax ; ax = ds = 0 (used by lgdt) 
mov ds, ax 
lgdt [gdtr] ; Load the GDT (segmentation) 
mov eax, cr0 
or al, 1 ; Protected mode bit <- 0 
mov cr0, eax 
;jmp $ 
jmp SYS_CODE_SEL:clear_pipe 

;---------------------- PM--------------------------------------------; 
[BITS 32] 
clear_pipe: 
mov ax, SYS_DATA_SEL ; Update DATA Segment 
mov ds, ax 
mov ss, ax 
mov esp, 9000h 

k_launch: 
;jmp $ ; Uncomment this for testing 
;jmp KSEG:0 ; give the hand to the kernel 
jmp 1000h 


;-----------------VARS---------------------------------------------------;  
takeoff db "HI !!",13,10,0 
success db "Bootsector: Kernel copy successful !!",13,10,0 
error db "Bootsector: Kernel copy error >O<",13,10,0 

;GDT Table Definition for segmentation 
[BITS 32] 

gdtr: 
dw gdt_end - gdt - 1 ; GDT limit 
dd gdt ; GDT base 

gdt: 
times 8 db 0 ; NULL Descriptor 

SYS_CODE_SEL equ $-gdt 
dw 0xFFFF ; limit 15:0 
dw 0 ; base 15:0 
db 0 ; base 23:16 
db 0x9A ; type = present, ring 0, code, non-conforming, readable 
db 0xCF ; page granular, 32-bit 
db 0 ; base 31:24 

SYS_DATA_SEL equ $-gdt 
dw 0xFFFF ; limit 15:0 
dw 0 ; base 15:0 
db 0 ; base 23:16 
db 0x92 ; type = present, ring 0, data, expand-up, writable 
db 0xCF ; page granular, 32-bit 
db 0 ; base 31:24 

gdt_end: 

;-------------------MISC
FUNCS-------------------------------------------; 

;Very simplified print in real mode 
bprint: 
push ax 
push bx 

.next: 
lodsb ; Load ds:si word to al 
cmp al, 0 ; if 0x0 => end of string 
jz .end 
mov ah, 0x0E ; 0x0e BIOS service -> print to screen 
mov bx, 0x0004 ; bx -> attribut (red), al -> caractere ascii 
int 0x10 ; INT !! 
jmp .next 

.end: 
pop bx 
pop ax 
ret 


;-------------------Boot sector
signature-------------------------------; 

times 510 - ($ - $$) db 0 
dw 0xAA55 

******************************kern.c**************** 
void main(void) { 
for (;;); 
} 

******************************BOCHS output**********
00300095414e[CPU ] exception(): 3rd (13) exception with no resolution,
shutdow