What about StageBomb - pbsds 15:12, 17 June 2009 (UTC+1) -Preceding undated comment added 13:17, 17 June 2009 (UTC). Obviously, I just thought I'd add my two cents worth :P - Master5o1 01:48, 9 June 2009 (UTC) however the video title is catchy.- ChuckBartowski 23:21, 8 June 2009 (UTC) I just thought of this potentially lame rewrite of the "Confirmed For Brawl" meme as a possible name for the new exploit ) two amazing wii exploits, one iPhone jail break and the first iPad jail break I mean you could possibly be better than marcan Wright 11:10, 9 April 2010 (UTC) ChuckBartowski 06:32, (UTC)Ĭomex made it with the Humorous thing, then ShuyGuy removed it and added it again. With any luck you should be viewing function main in the debugger.This page is kept because it is humorous. 0xb8000 can be represented as segment:offset 0xb800:0x0 (Computed as (0xb800 to continue. In order to access the video ram 0xb8000 we need to use a segment:offset pair that represents the same thing. The primary difference (in 16-bit code) is that we no longer use EAX and EDX 32-bit registers. Pop es Restore ES that was saved on entry Mov word, ax Store char and attributes at currentĪdd bx, 1 Increment BX to the next char in string.Īdd di, 2 Move to next character cell in vid mem. Push VIDEO_MEMORY_SEG Video mem segment 0xb800 Push es Save ES on stack and restore when we finish
#BOOT.ELF FOR SMASHSTACK CODE#
The code can be made 16-bit with some adjustments: prints a null - terminated string pointed to by EBX You can't use the 32-bit registers and addressing.
You call print_string as an error handler in 16-bit code so what you are doing here will likely force a reboot of the computer. prints a null - terminated string pointed to by EBX You have written some print_string code but it is 32-bit code: When in 16-bit Real Mode Don't Use 32-bit Code It actually appears that the second dd 0 was accidentally added to the end of the comment on the previous line. It should be: gdt_start:ĭd 0 null descriptor-just fill 8 bytes The single largest bug that would have prevented you from getting far into protected mode was that you set up the global descriptor table (GDT) in gdt.inc starting with: gdt_start:Įach global descriptor needs to be 8 bytes but dd 0 defines just 4 bytes (double word). Although in your code it doesn't appear to be the case (except in the print_string function which I'll discuss later). They should be set upĪppropriately when your bootloader starts. Registers having valid or expected values. When the BIOS jumps to your code you can't rely on CS,DS,ES,SS,SP The original code in your question didn't set the SS stack segment register. Don't Assume the Segment Registers are Set Properly I have written a StackOverflow answer that has tips for general bootloader development. There are a number of issues, but in general your assembly code does work. When testing I use: qemu-system-i386 -kernel os.binĭd 0 null descriptor-just fill 8 bytes dd 0ĭw end_of_gdt - gdt_start - 1 limit (Size of GDT) Can someone give some tips to improve kernel.c so I don't have to use the call_main() function? I want to know what I am doing wrong because when I test with QEMU it doesn't work. I compile it with this: gcc -ffreestanding -o kernel.bin kernel.cĪnd then: cat boot.bin kernel.bin > os.bin I compile it with this: nasm -f bin -o boot.bin bootloader.asm Jmp print_string_loop loop around to print the next char. Mov, ax Store char and attributes at currentĪdd ebx, 1 Increment EBX to the next char in string.Īdd edx, 2 Move to next character cell in vid mem. Mov ah, WHITE_ON_BLACK Store the attributes in AHĬmp al, 0 if (al = 0), at end of string, so Mov edx, VIDEO_MEMORY Set edx to the start of vid mem. prints a null - terminated string pointed to by EDX carry flag set )Ĭmp dh, al if AL ( sectors read ) != DH ( sectors expected ) Mov cl, 0x02 Start reading from second sector ( i.e. how many sectors were request to be read , Push dx Store DX on stack so later we can recall
I'm trying to make my own custom OS and I need some help with my code.
0 kommentar(er)
