wip: load kernel from FAT
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3d4615d276
commit
7455b79585
3 changed files with 96 additions and 47 deletions
12
Makefile
12
Makefile
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@ -1,7 +1,9 @@
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all: stupid.img
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all: stupid.img kern.bin
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stupid.img: floppy.bin kern.bin
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cat $^ /dev/zero | dd of=$@ bs=512 count=2880
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mkdosfs -F 12 -C $@ 1440
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dd status=noxfer conv=notrunc if=floppy.bin of=$@
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mcopy -i $@ kern.bin ::kern.sys
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floppy.bin: boot/floppy.s
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nasm -fbin -o $@ $^
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@ -10,10 +12,10 @@ kern.bin: kern/kernel.s
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nasm -fbin -o $@ $^
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clean:
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rm floppy.bin kern.bin
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rm -rf floppy.bin kern.bin
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fclean:
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rm stupid.img
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fclean: clean
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rm -rf stupid.img
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re: fclean all
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130
boot/floppy.s
130
boot/floppy.s
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@ -9,24 +9,64 @@
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;; -----------------------------------------------------------
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db "StupidOS"
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dw 512 ; bytes per sector
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db 1 ; sector per cluster
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dw 1 ; reserved sector
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db 2 ; number of FATs
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dw 224 ; root entries
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dw 2400 ; total sector
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db 0xF9 ; media descriptor type
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dw 7 ; sectors per FAT
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dw 15 ; sectors per track
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dw 2 ; heads per cylinder
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dd 0 ; hidden sectors
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dd 0 ; total sector big
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db 0 ; drive number
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db 0 ; unused
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db 0x29 ; drive signature (0x29 = floppy)
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dd 0x00000000 ; serial number (ignore)
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db 'STUPID DISK' ; volume label
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db 'FAT12 ' ; filesystem type
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bpb_bytes_per_sector dw 512 ; bytes per sector
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bpb_sectors_per_cluster db 1 ; sector per cluster
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bpb_reserved_sectors dw 1 ; reserved sector
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bpb_number_of_fats db 2 ; number of FATs
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bpb_root_entries dw 224 ; root entries
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bpb_total_sectors dw 2880 ; total sector
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bpb_media db 0xF0 ; media descriptor type
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bpb_sectors_per_fat dw 9 ; sectors per FAT
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bpb_sectors_per_track dw 18 ; sectors per track
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bpb_heads_per_cylinder dw 2 ; heads per cylinder
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bpb_hidden_sectors dd 0 ; hidden sectors
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bpb_total_sector_big dd 0 ; total sector big
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bpb_drive_number db 0 ; drive number
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bpb_unused db 0 ; unused
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bpb_signature db 0x29 ; drive signature (0x29 = floppy)
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bpb_serial_number dd 0x00000000 ; serial number (ignore)
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bpb_volume_label db 'STUPID DISK' ; volume label
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bpb_filesystem db 'FAT12 ' ; filesystem type
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;; -----------------------------------------------------------
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;; entry
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;; -----------------------------------------------------------
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entry:
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xor ax, ax
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mov ds, ax
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mov si, msg_boot
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call boot_print
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mov si, msg_copyright
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call boot_print
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reset_disk:
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xor ah, ah
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xor dl, dl
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int 0x13
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jc reset_disk
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;; load kernel from FAT
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;; store size of root dir in cx
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xor cx, cx
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xor dx, dx
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mov ax, 0x0020
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mul word [bpb_root_entries]
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div word [bpb_bytes_per_sector]
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xchg ax, cx
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;; store loc of root directory in ax
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mov al, byte [bpb_number_of_fats]
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mul word [bpb_sectors_per_fat]
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add ax, word [bpb_reserved_sectors]
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;; mov word [datasec], ax
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;; mov word [datasec], cx
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mov bx, 0x0200
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hang:
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jmp hang
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cli
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hlt
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;; -----------------------------------------------------------
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;; Print string using bios interrupt
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@ -45,36 +85,42 @@ boot_print:
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popa
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ret
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fatal_error:
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pusha
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mov cx, si
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mov si, msg_error
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call boot_print
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mov si, cx
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call boot_print
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mov si, msg_press_any_key
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call boot_print
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xor ax, ax
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int 0x16 ; wait keypressed
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int 0x19 ; reboot
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popa
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ret
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disk_read_sector:
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pusha
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popa
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ret
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;; -----------------------------------------------------------
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;; Variables
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;; -----------------------------------------------------------
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copyright db "Copyright (c) d0p1", 13, 10, 0
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err_disk_reset db "Error reseting disk..retry", 13, 10, 0
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msg_boot db "StupidOS - Bootloader", 13, 10, 0
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msg_copyright db "Copyright (c) d0p1", 13, 10, 0
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msg_press_any_key db "Press any key...", 13, 10, 0
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msg_error db "[ERROR] ", 0
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err_kern_not_found db "KERNEL.BIN not found...", 13, 10, 0
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kernel_filename db "KERNEL BIN"
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;; -----------------------------------------------------------
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;; entry
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;; End
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;; -----------------------------------------------------------
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entry:
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xor ax, ax
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mov ds, ax
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mov si, copyright
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call boot_print
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reset_disk:
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xor ah, ah
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xor dl, dl
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int 0x13
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jnc .reset_disk_end
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mov si, err_disk_reset
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call boot_print
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jmp reset_disk
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.reset_disk_end:
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hang:
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jmp hang
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cli
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hlt
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times 510-($-$$) db 0
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db 0x55
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db 0xAA
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@ -0,0 +1 @@
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[BITS 16]
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