准备:
nasm
qemu
安装nasm和qemu：
sudo apt-get install nasm
sudo apt-get install qemu
编写bootloader文件，命名为mybootloader.asm：
[BITS 16] ;Tells the assembler that its a 16 bit code [ORG 0x7C00] ;Origin, tell the assembler that where the code will ;be in memory after it is been loaded MOV SI, HelloString ;Store string pointer to SI CALL PrintString ;Call print string procedure JMP $ ;Infinite loop, hang it here. PrintCharacter: ;Procedure to print character on screen ;Assume that ASCII value is in register AL MOV AH, 0x0E ;Tell BIOS that we need to print one charater on screen. MOV BH, 0x00 ;Page no. MOV BL, 0x07 ;Text attribute 0x07 is lightgrey font on black background INT 0x10 ;Call video interrupt RET ;Return to calling procedure PrintString: ;Procedure to print string on screen ;Assume that string starting pointer is in register SI next_character: ;Lable to fetch next character from string MOV AL, [SI] ;Get a byte from string and store in AL register INC SI ;Increment SI pointer OR AL, AL ;Check if value in AL is zero (end of string) JZ exit_function ;If end then return CALL PrintCharacter ;Else print the character which is in AL register JMP next_character ;Fetch next character from string exit_function: ;End label RET ;Return from procedure ;Data HelloString db 'Hello World', 0 ;HelloWorld string ending with 0 TIMES 510 - ($ - $$) db 0 ;Fill the rest of sector with 0 DW 0xAA55 ;Add boot signature at the end of bootloader
编译mybootloader.asm:
nasm mybootloader.asm -f bin -o boot.bin
运行qemu, 加载bootloader:
qemu-system-i386 boot.bin
结果如图：
