How to build?
as -32 -o ./main.o ./main.s
ld -m elf_i386 -T ld.script -o ./a.out ./main.o
objcopy -j .text -j .data -O binary ./a.out ./boot.text.bin
Last active
May 9, 2017 19:18
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BIOS hello world
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| SECTIONS | |
| { | |
| . = 0x00007C00; | |
| .text : { | |
| _text_start = .; | |
| *(.text) | |
| _text_end = .; | |
| } | |
| .data : { | |
| _rodata_start = .; | |
| *(.rodata) | |
| _rodata_end = .; | |
| _data_start = .; | |
| *(.data) | |
| _data_end = .; | |
| } | |
| } |
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| .file "main.s" | |
| .text | |
| .code16 | |
| .globl _start | |
| _start: | |
| cli | |
| cld | |
| xor %ax, %ax | |
| movw %ax, %ss | |
| movw $_start + 0x400, %bp | |
| movw %bp, %sp | |
| movw %ax, %ds | |
| movw %ax, %es | |
| _main: | |
| movb $0x00, %ah | |
| movb $0x12, %al | |
| int $0x10 | |
| movb $0x02, %ah | |
| movb $0x00, %bh | |
| movb $0x00, %dh | |
| movb $0x00, %dl | |
| int $0x10 | |
| movb $0x61, %al | |
| call _putc | |
| movb $0x62, %al | |
| call _putc | |
| movb $0x63, %al | |
| call _putc | |
| movb $0x0a, %al | |
| call _putc | |
| movb $0x0d, %al | |
| call _putc | |
| mov $_mesg, %si | |
| call _puts | |
| _finish: | |
| hlt | |
| jmp _finish | |
| _puts: | |
| pushw %bp | |
| movw %sp, %bp | |
| _puts.func: | |
| lodsb | |
| testb %al, %al | |
| jz _puts.finish | |
| call _putc | |
| jmp _puts.func | |
| _puts.finish: | |
| leave | |
| ret | |
| _putc: | |
| pushw %bp | |
| movw %sp, %bp | |
| movb $0x0e, %ah | |
| movb $0x00, %bh | |
| movb $0xd7, %bl | |
| int $0x10 | |
| leave | |
| ret | |
| .section .rodata | |
| _mesg: | |
| .asciz "Hello, world.\r\n" |
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