OSDev.org

Posted: **Thu May 06, 2010 6:27 pm**

when i try to load my os, this msg appear.

i didnt find out any answer about it.

this stuff maybe help:

objdump -h ./bin/kernel.bin

./bin/kernel.bin: file format elf32-i386

Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00003ca2 00100000 00100000 00001000 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .rodata 00000e06 00104000 00104000 00005000 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .data 00000320 00105000 00105000 00006000 2**5
CONTENTS, ALLOC, LOAD, DATA
3 .bss 0000bac8 00105320 00105320 00006320 2**5
ALLOC
4 .comment 00000023 00000000 00000000 00006320 2**0
CONTENTS, READONLY

compile:

cd ./bin
rm -rf *
nasm -f elf ../src/libasm.asm -o libasm.o
nasm -f elf ../src/kstart.asm -o kstart.o
nasm -f elf ../src/loader.asm -o kstart.o
gcc -c ../src/kernel.c -o kernel.o -fno-builtin -fno-stack-protector
gcc -c -fno-stack-protector ../src/libc.c -o libc.o -fno-builtin
gcc -c ../src/buffer.c -o buffer.o -fno-builtin
gcc -c ../src/bufferTeclado.c -o bufferTeclado.o -fno-builtin
gcc -c ../src/initMouse.c -o initMouse.o -fno-builtin
gcc -c ../src/mouse.c -o mouse.o -fno-builtin
gcc -c ../src/video.c -o video.o -fno-builtin
gcc -c ../src/protpant.c -o protpant.o -fno-builtin
gcc -c ../src/paginacion.c -o paginacion.o -fno-builtin
gcc -c ../src/string.c -o string.o -fno-builtin
gcc -c ../src/sched.c -o sched.o -fno-builtin -fno-stack-protector
gcc -c ../src/malloc.c -o malloc.o -fno-builtin
ld -T ../src/link.ld -o kernel.bin kernel.o kstart.o libc.o libasm.o bufferTeclado.o buffer.o video.o initMouse.o mouse.o protpant.o paginacion.o string.o sched.o malloc.o

thx.

Posted: **Thu May 06, 2010 6:48 pm**

I'm guessing either your multiboot header is incorrect, or in an ELF section that is too far from the beginning of the kernel. Try putting the multiboot header in a new section, or near the beginning of .text. Also, you really shouldn't have "rm -rf *" anywhere in a build script...

Posted: **Thu May 06, 2010 7:00 pm**

rm is for remove old objects when i'm compiling. how i put in a new section?

this are my constants
MULTIBOOT_PAGE_ALIGN equ 1<<0 ; Alineado a 4KB ( pagina )
MULTIBOOT_MEMORY_INFO equ 1<<1
MULTIBOOT_AOUT_KLUDGE equ 1<<16 ; Indica que los offset del 8 al 24 en el header son
; validos para extraer información.

MULTIBOOT_HEADER_MAGIC equ 0x1BADB002
MULTIBOOT_HEADER_FLAGS equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE
MULTIBOOT_CHECKSUM equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)

my kstart.asm:
[BITS 32]

[global start]
[extern kmain] ; en kernel.c

start:

call kmain

jmp $

EXTERN code, bss, end
ALIGN 4
mboot:
dd MULTIBOOT_HEADER_MAGIC
dd MULTIBOOT_HEADER_FLAGS
dd MULTIBOOT_CHECKSUM

dd mboot
dd code
dd bss
dd end
dd start

Posted: **Thu May 06, 2010 7:09 pm**

Do an objdump -d or -D and see whether the header is in the first 8k and 32bit aligned.

Is the header in kernel.o ? or kstart .o ? Careful of the link order.

- gerryg400

Posted: **Thu May 06, 2010 7:50 pm**

objdump -d kstart.o

Code: Select all

kstart.o:     file format elf32-i386


Disassembly of section .text:

00000000 <MultiBootHeader>:
   0:	02 b0 ad 1b 03 00    	add    0x31bad(%eax),%dh
   6:	00 00                	add    %al,(%eax)
   8:	fb                   	sti    
   9:	4f                   	dec    %edi
   a:	52                   	push   %edx
   b:	e4 bc                	in     $0xbc,%al

0000000c <_loader>:
   c:	bc 00 40 00 00       	mov    $0x4000,%esp
  11:	50                   	push   %eax
  12:	53                   	push   %ebx
  13:	e8 fc ff ff ff       	call   14 <_loader+0x8>
  18:	f4                   	hlt    

00000019 <eokl>:
  19:	00 40 00             	add    %al,0x0(%eax)

is it ok??

thx again!

Posted: **Thu May 06, 2010 8:11 pm**

cazador4,

I don't think you should set bit 16 if you are loading and ELF file. My code looks like this.

Code: Select all

start:
		jmp	over_multiboot_header

		.align	4
		.long	0x1badb002  /* multiboot magic number */
		.long	0x00000003  /* ELF file multiboot flags */
		.long	-(0x1badb002 + 0x00000003)  /* checksum */

over_multiboot_header:

- gerryg400

Posted: **Fri May 07, 2010 8:09 am**

cazador4 wrote: how i put in a new section?

Code: Select all

[SECTION section_name] ; General
[SECTION .text] ; Example: use text section.

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