217 lines
3.6 KiB
NASM
217 lines
3.6 KiB
NASM
;; File: loader.asm
|
|
format binary
|
|
|
|
include '../common/const.inc'
|
|
include '../common/macro.inc'
|
|
include 'multiboot.inc'
|
|
|
|
org LOADER_BASE
|
|
use32
|
|
|
|
jmp _start
|
|
|
|
align 4
|
|
multiboot_header:
|
|
mb_header MultibootHeader multiboot_header
|
|
|
|
_start:
|
|
cmp eax, MULTIBOOT_MAGIC
|
|
je multiboot
|
|
|
|
use16
|
|
align 2
|
|
|
|
; =========================================================================
|
|
; real mode code
|
|
; =========================================================================
|
|
push cs
|
|
pop ds
|
|
|
|
mov [uDrive], dl
|
|
|
|
mov si, szMsgStage2
|
|
call bios_log
|
|
|
|
; enable A20 line
|
|
call a20_enable
|
|
jc .error_a20
|
|
|
|
; check drive type
|
|
; dl <= 0x7F == floppy
|
|
; dl >= 0x80 == hard drive
|
|
; dl == 0xE0 ~= CD/DVD
|
|
; dl <= 0xFF == hard drive
|
|
mov dl, [uDrive]
|
|
cmp dl, 0x7F
|
|
; skip disk extension check
|
|
jle @f
|
|
|
|
; check disk extensions
|
|
mov ah, 0x41
|
|
mov bx, 0x55AA
|
|
int 0x13
|
|
jc @f
|
|
mov [bDriveLBA], TRUE
|
|
@@:
|
|
; detect filesystem (FAT12/16 or StpdFS)
|
|
; load kernel from filesystem
|
|
|
|
; StupidFS layout
|
|
; +---------+---------+---------....--+----....---+
|
|
; | bootsec | stpd sb | i-nodes ... | data |
|
|
; +---------+---------+---------....--+----....---+
|
|
; 0 512 1024 XXXX XXXX
|
|
;
|
|
|
|
; for now fat12 is asumed
|
|
|
|
call fat_load_root
|
|
|
|
mov si, szKernelFile
|
|
call fat_search_root
|
|
jc .error_not_found
|
|
mov [pKernelStartFat], ax
|
|
mov [uKernelSize], ebx
|
|
|
|
push ebx
|
|
mov si, szMsgKernelFound
|
|
call bios_log
|
|
|
|
; load fat
|
|
xor ax, ax
|
|
mov al, [FAT_count]
|
|
mul word [sectors_per_FAT]
|
|
mov cx, ax
|
|
mov ax, [reserved_sectors]
|
|
|
|
xor bx, bx
|
|
|
|
call disk_read_sectors
|
|
|
|
; load stage 2
|
|
mov ax, KERNEL_PRELOAD/0x10
|
|
mov es, ax
|
|
mov ax, [pKernelStartFat]
|
|
xor bx, bx
|
|
call fat_load_binary
|
|
|
|
; fetch memory map from bios
|
|
call memory_get_map
|
|
jc .error_memory
|
|
|
|
xchg bx, bx
|
|
|
|
call boot_info_print_mmap
|
|
|
|
; video information
|
|
call video_setup
|
|
|
|
; load GDT and enter Protected-Mode
|
|
lgdt [gdt_ptr]
|
|
|
|
; enable protected mode
|
|
mov eax, cr0
|
|
or al, 1
|
|
mov cr0, eax
|
|
|
|
; reload ds, es, fs, gs, ss
|
|
mov ax, 0x10
|
|
mov ds, ax
|
|
mov es, ax
|
|
mov fs, ax
|
|
mov gs, ax
|
|
mov ss, ax
|
|
jmp 0x8:common32
|
|
|
|
.error_not_found:
|
|
mov si, szMsgErrorNotFound
|
|
jmp .error
|
|
.error_memory:
|
|
mov si, szMsgErrorMemory
|
|
jmp .error
|
|
.error_a20:
|
|
mov si, szMsgErrorA20
|
|
.error:
|
|
call bios_log
|
|
|
|
@@:
|
|
hlt
|
|
jmp @b
|
|
|
|
include 'a20.inc'
|
|
include '../common/bios.inc'
|
|
include '../common/fat12.inc'
|
|
include 'disk.inc'
|
|
include 'logger.inc'
|
|
include 'memory.inc'
|
|
include 'video.inc'
|
|
include 'gdt.inc'
|
|
include '../common/bootinfo.inc'
|
|
|
|
uDrive rb 1
|
|
bDriveLBA db FALSE
|
|
|
|
pKernelStartFat dw 0
|
|
uKernelSize dd 0
|
|
|
|
szMsgStage2 db "StupidOS Loader", 0
|
|
szKernelFile db "VMSTUPIDSYS", 0
|
|
szMsgKernelFound db "Kernel found, size: %x", 0
|
|
szMsgErrorA20 db "ERROR: can't enable a20 line", 0
|
|
szMsgErrorMemory db "ERROR: can't detect available memory", 0
|
|
szMsgErrorSector db "ERROR: reading sector", CR, LF, 0
|
|
szMsgErrorNotFound db "ERROR: kernel not found", 0
|
|
|
|
use32
|
|
; =========================================================================
|
|
; protected mode code
|
|
; =========================================================================
|
|
multiboot:
|
|
; https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#Machine-state
|
|
|
|
; get screen information
|
|
|
|
; get memory map
|
|
|
|
; get kernel from module
|
|
|
|
|
|
common32:
|
|
mov [0xB8000], dword 0x07690748
|
|
|
|
; paging
|
|
; identity map first 1MB
|
|
; map kernel to 0xC000000
|
|
; -----------------------
|
|
mov edi, boot_768_page_table
|
|
mov esi, 0
|
|
mov ecx, 1023
|
|
.1:
|
|
cmp esi, MULTIBOOT_BASE
|
|
jl .2
|
|
.2:
|
|
|
|
|
|
.3:
|
|
|
|
push STPDBOOT_MAGIC
|
|
|
|
mov eax, 0xC0000000
|
|
jmp eax
|
|
hang:
|
|
hlt
|
|
jmp $
|
|
|
|
_edata:
|
|
|
|
boot_structure BootInfo
|
|
|
|
align 4096
|
|
boot_page_directory:
|
|
rb 4096
|
|
|
|
boot_768_page_table:
|
|
rb 4096
|
|
|
|
_end:
|