diff options
Diffstat (limited to 'boot/mbr.asm')
| -rw-r--r-- | boot/mbr.asm | 140 |
1 files changed, 67 insertions, 73 deletions
diff --git a/boot/mbr.asm b/boot/mbr.asm index 96fc788..bb74d23 100644 --- a/boot/mbr.asm +++ b/boot/mbr.asm @@ -39,121 +39,115 @@ ;The Boot record is identified by the last 2 magic bytes: 0xaa55 (?) [org 0x7c00] -;define some constants -;where we will load our kernel into memory and some -;other memory locations - +;;define some constants +;;where we will load our kernel into memory and some +;;other memory locations +; KERNEL_OFFSET equ 0x1000 MEMMAP_SIZE_OFFSET equ 0x7c00+0x600 MEMMAP_OFFSET equ 0x7c00+0x400 VESA_MODES equ 0x8300 VESA_MODE_INFO equ 0x8400 VESA_MODE_SELECT equ 0x4114 -;VESA_MODE_SELECT equ 0x0 - +; jmp boot_16 ;start boot process - -;SOME Global Data, mainly info/error strings +; +;;SOME Global Data, mainly info/error strings BOOT_DRIVE: db 0xff STR_VERSION: - db "v0.3.1~",0 + db "v0.4",0 VESA_CHECK1: - db " V1.",0 + db "1",0 VESA_CHECK2: - db " V2",0 + db "2",0 VESA_CHECK3: - db " V3",0 + db "3",0 CHECK_A20: - db " A20",0 - -;lets put our temporary GDT (Global Descriptor Table) here -;kernel should move this away + db "A",0 +; +;;lets put our temporary GDT (Global Descriptor Table) here +;;kernel should move this away %include "boot/GDT.asm" - -;include 16-bit real mode routines (print_string, disk_load, vesa_setup,check_a20) +; +;;include 16-bit real mode routines (print_string, disk_load, vesa_setup,check_a20) %include "boot/disk_load_16.asm" -%include "boot/check_a20_16.asm" +;%include "boot/check_a20_16.asm" %include "boot/print_string_16.asm" %include "boot/vesa_setup_16.asm" - -;include our routines for switching to 32-bit protected mode +; +;;include our routines for switching to 32-bit protected mode %include "boot/pm.asm" - -;pic_setup mapping routing -%include "boot/pic.asm" - -;get memory map routine +; +; +;;get memory map routine %include "boot/memmap.asm" - -;;;;;;;; BOOT 16-bit real ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - -;lets start +; +;;;;;;;;; BOOT 16-bit real ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; +;;lets start [bits 16] - +; boot_16: - +; +; mov bx, STR_VERSION call print_string - - ;setup the stack +; +; +; ;setup the stack mov bp,0x8000 mov sp,bp - - ;remember BOOT_DRIVE (as was set by BIOS) +; +; ;remember BOOT_DRIVE (as was set by BIOS) mov [BOOT_DRIVE],dl - - ;Load the KERNEL (52 sectors starting at sector 2) +; mov bx, BOOT_DRIVE +; call print_string +; +; ;Load the KERNEL (52 sectors starting at sector 2) mov bx,KERNEL_OFFSET mov dh, 52 mov dl, [BOOT_DRIVE] call disk_load - ;get memory map from bios before we enter 32 bit protected mode + mov bx, KERNEL_OFFSET + call print_string + +; +; ;get memory map from bios before we enter 32 bit protected mode mov ax,0 ; set target address in es:di (0:offset) mov es,ax mov di,MEMMAP_OFFSET call BiosGetMemoryMap ; this will also put the number of entries - ; of the memory map at MEMMAP_SIZE_OFFSET - -a20check: - - mov bx, CHECK_A20 - call print_string - - call check_a20 - cmp ax,0 - je a20check ;hang if a20 is disabled! - - ;VESA: also setup vesa stuff before entering 32 bit protected mode +; ; of the memory map at MEMMAP_SIZE_OFFSET +; +;a20check: +; +; mov bx, CHECK_A20 +; call print_string +; +; call check_a20 +; cmp ax,0 +; je a20check ;hang if a20 is disabled! +; +; ;VESA: also setup vesa stuff before entering 32 bit protected mode call VesaSetup - - ;finally lets enter Protected mode!!! +; +; ;finally lets enter Protected mode!!! call switch_to_pm - -;;;;;;;; BOOT 32-bit protected mode;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; +;;;;;;;;; BOOT 32-bit protected mode;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; [bits 32] boot_32_pm: +; -; we could do ALL This inside the kernel!!!!!! TODO - - ;enable A20 - ;http://www.brokenthorn.com/Resources/OSDev9.html - ;Method 3.1: Enables A20 through keyboard controller - ;Not all keyboard controllers support this - ;todo: check if this has any effect at all !?!? - ;mov al, 0xdd ; command 0xdd: enable a20 - ;mov al, 0xdf ; command 0xdf: disable a20 - ;out 0x64, al ; send command to controller - - ;pic setup - call pic_setup - +; call KERNEL_OFFSET ;jump into our Kernel! - -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - +; +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; ;so we get identified as MBR -times 510-($-$$) db 0 +times 510-($-$$) db 0x0 +;dw 0x0 dw 0xaa55 |