Creating a multiboot ELF image

[jmmv]

I'm new to the forum, HI ALL!

I'm starting some kernel stuff, just for fun ;D I've been at the FAQ but I didn't find answers to my questions. So, here they go:

I don't know how to compile an elf-multiboot kernel image. I've created a little head.asm file with a silly multiboot header and a main.c file that just contains an endless main() function (with a 'for' inside).

I assemble head.asm with:
nasm -f elf head.as head.o

I compile main.c with:
gcc -o main.o -c main.c

Then, I join them with the following command:
ld -Ttext 0x100000 -e start --oformat elf32-i386 boot/head.o kernel/main.o -o mykernel.o

But when trying to load the image file with GRUB, it says that it is invalid.

Are these commands valid for the compilation??

My silly multiboot header is now:

align 32
dd 0x1BADB002 ; Magic
dd 0 ; Flags...
dd 0 ; What here?

Am I supposed to create a valid Multiboot header inside the file? Where can I get good info about this? And an (clear) example?

Thanks a lot!!

PS: Maybe this should go to the FAQ, isn't it?  ;)

[Chris Giese]

You may need to set the checksum in the Multiboot header (your "What here?" field).

You can use "mbchk" before booting to see if the Multiboot header is OK.

http://www.washingdishes.freeuk.com/grubtut.html
http://www.execpc.com/~geezer/osd/boot/grub-how.txt