OSDev.org

Posted: **Wed Nov 11, 2009 7:59 am**

thanks OdinPG. you have been more than useful. but the output_arch option in the link file does the same as the melf-i386... it doesn't work :S
I don't want to bother you. But if you don't mind. would you please test it in a 64 bit machine? If it's working on yours I'm going to start thinking this is a problem with grub. or something else.

Posted: **Wed Nov 11, 2009 9:05 am**

Yet another frequent problem. GCC Cross-Compiler

Posted: **Wed Nov 11, 2009 9:44 am**

I tried to build it on my 64 bit machine, but i got the following errors:

Code: Select all

text_services.asm:169: error: short jump is out of range
text_services.asm:172: error: short jump is out of range
ld: text_services.o: No such file: No such file or directory

I don't know why, but may be you got that too and fixed it?

Posted: **Wed Nov 11, 2009 9:59 am**

no. I didn't have that error. but try updating nasm to the latest version

Also I found this solutions in google:
"You need to add -O99 to the NASM variable."

Thanks for taking the time to test this. I'll try the gcc cross compiler guide... even thought I'm not using gcc... it's completely written in assembly language...

Posted: **Thu Nov 12, 2009 10:25 am**

Okay.
It compiles with the option "-O99". When I update the image (mount floppy image and copy kernels binary on it), I got the GRUB 13 Error. After this I used my on Floppy image an there the Error 28 "Selected item cannot fit into memory" occurs.

This Error occured, because your linker script was wrong: Now it looks like this:

Code: Select all

/*OUTPUT_ARCH ( "i386" )
OUTPUT_FORMAT("binary")*/
OUTPUT_FORMAT("elf32-i386")
ENTRY(start)
phys = 0x00100000;
SECTIONS
{
   /*
    * http://wiki.osdev.org/Grub_Error_13
    */
   . = phys;
   /* .__mbHeader will begin @ 'phys' */
   .__mbHeader : AT ( ADDR( .__mbHeader ) ) {
      /* mboot = .;*/
      *(.__mbHeader)
   }
  .text : AT(ADDR(.text)) {
    code = .;
    *(.text)
    *(.rodata)
    . = ALIGN(4096);
  }
  .data : AT(ADDR(.text) + (data - code))
  {
    data = .;
    *(.data)
    . = ALIGN(4096);
  }
  .bss : AT(ADDR(.text) + (bss - code))
  {
    bss = .;
    *(.bss)
    . = ALIGN(4096);
  }
  end = .;
}

Your compile script within src looks like this:

Code: Select all

rm *.o
nasm -O99 -f elf32 -o text_services.o text_services.asm
nasm -O99 -f elf32 -o kernel.o kernel.asm
nasm -O99 -f elf32 -o start.o start.asm
nasm -O99 -f elf32 -o system.o system.asm
nasm -O99 -f elf32 -o isr.o isr.asm
ld -T link.ld -melf_i386 -o kernel.bin start.o kernel.o text_services.o system.o isr.o

The file start.asm is the same as before, with SECTION .__mbHeader.

Code: Select all

; This is the kernel's entry point. We could either call main here,
; or we can use this to setup the stack or other nice stuff, like
; perhaps setting up the GDT and segments. Please note that interrupts
; are disabled at this point: More on interrupts later!
[BITS 32]

SECTION .__mbHeader
; This part MUST be 4byte aligned, so we solve that issue using 'ALIGN 4'
ALIGN 4
mboot:
    ; Multiboot macros to make a few lines later more readable
    MULTIBOOT_PAGE_ALIGN   equ 1<<0
    MULTIBOOT_MEMORY_INFO   equ 1<<1
    MULTIBOOT_AOUT_KLUDGE   equ 1<<16
    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)
    EXTERN code, bss, end
;...

At last I copied the created kernel on your image and it seems that it is broken, because there Error 13 occurs.

Hope it helps...
Cheers Christian

PS: This is the way I created my floppy image:

Code: Select all

	dd if=/dev/zero of=./floppy.ext2.img bs=1024 count=1440
	/sbin/mke2fs -F ./floppy.ext2.img -L MyOS
	mount ./floppy.ext2.img ./flp -o loop
	mkdir ./flp/boot
	mkdir ./flp/boot/grub
	mkdir ./flp/modules
	mkdir ./flp/system
	mkdir ./flp/system/drivers
	cp kernel.elf ./flp/boot
	cp ./src/modules/initrd.tar ./flp/modules
	cp /boot/grub/stage1 ./flp/boot/grub
	cp /boot/grub/stage2 ./flp/boot/grub
	cp menu.lst ./flp/boot/grub
	umount ./flp
	grep -v ^# ./grub.conf | /usr/sbin/grub --batch

Posted: **Sat Nov 14, 2009 8:43 am**

thank you so much for taking this time. I really appreciate it...

I couldn't make it work either. and it's strange... it's working on a 32 bits machine (you tested it, I don't have a 32bit OS) and not working with 64 bit linkers (we both tried this).

This is the (partial) output of objdump -s:

This kernel is Not Working:

Code: Select all

kernelNW.bin:     file format elf32-i386

Contents of section .__mbHeader:
 100000 02b0ad1b 03000100 fb4f51e4 00001000  .........OQ.....
 100010 20001000 00301000 00601000 20001000   ....0...`.. ...
Contents of section .text:
 100020 0f011500 20100066 b810008e d88ec08e  .... ..f........
 100030 e08ee88e d0ea3c00 10000800 bc005010  ......<.......P.

...

And this is working:

Code: Select all

kernel.bin:     file format elf32-i386

Contents of section .__mbHeader:
 100000 02b0ad1b 03000100 fb4f51e4 00001000  .........OQ.....
 100010 20001000 00201000 00501000 20001000   .... ...P.. ...
Contents of section .text:
 100020 0f011500 10100066 b810008e d88ec08e  .......f........

...

of course I could just install a 32 bit OS and start developing the kernel there... but the question is... Why? it should be posible to do it in a 64 bit OS. There must be an error in my linker script... or.... a bug somewhere... in anyway... I know I made a mistake... but I don't know where

Posted: **Sun Nov 15, 2009 10:06 am**

Hmmm...
could you upload your current source code?
Further more try using a Crosscompiler, because there is a different version of "ld" within, what you use to link the kernel...

Posted: **Sun Nov 15, 2009 4:23 pm**

I was reading again you latest reply... so you actually made it work on the 64 bits machine using your own image instead of my floppy image? Maybe you loaded an updated grub version.

I thought I could do the same. but I was looking at your commands to create my own image witha newer grub but I have some missing files... for example:
what are you doing when you do this?
"grep -v ^# ./grub.conf | /usr/sbin/grub --batch"
Where is grub.conf and what does it have inside? and what about initrd.tar?

I followed this guide as you suggested:
http://wiki.osdev.org/GCC_Cross-Compiler
And used that linker. now I don't have to specify the output architecture cause I'm using the i586 linker. but it doesn't work anyway :S
I'm still getting the same error.

This is my current source code (using the cross compiler to compile 32 bit code):
http://rapidshare.com/files/307560009/e ... ar.gz.html
MD5: 1654F571D9A7616236F0B74EDC50AE13

I'm so embarrassed. I know developing an OS is not an easy task. But I feel useless not being able to solve this issue... Thanks for taking the time to help me

Posted: **Mon Nov 16, 2009 1:21 am**

Good Morning from Germany,
initrd.tar is my initial ramdisk and could be ignored.
The file grub.conf looks like this:

Code: Select all

device (fd0) ./floppy.ext2.img
root (fd0)
setup (fd0)

The version of GRUB I am using is "0.97". This is the one which is also used by my Linux distribution.
What happens there...
The command starts GRUB within the batch-mode. This means that "/usr/sbin/grub" will be executed and everything within the file "grub.conf" will be executed as command within the grub-shell. It is similar to the following steps:

Code: Select all

# start grub-shell
$> /usr/sbin/grub
# set image as device fd0
grub> device (fd0) /path/to/image
# set fd0 to root for grub
grub> root (fd0)
# install it
grub> setup (fd0)
# and quit the grub shell
grub> quit

I took a short look at your code, and it seems that you update your image by creating a new one. But where do you install GRUB? I do this with the line "grep -v ^# ./grub.conf | /usr/sbin/grub --batch" after creating, formatting the image and copying all the content. If you want, I'll upload my image...
EDIT: Okay, you created the image before, so there is no need to install GRUB

I will have a look at your code later, because at the moment I am at work.
Hope it helps...

Cheers Christian

PS: My English isn't good

Posted: **Mon Nov 16, 2009 7:54 pm**

I found it!!! I found the error!!

:D I'm so happy I could just take the whole night to drink a few beers!!! too bad I have to work tomorrow...

I successfully converted my kernel image from elf32 to bin. And to do so I had to manually set the code, mboot,start labels... and guess what? that was it!
This is where I got it:
http://forum.osdev.org/viewtopic.php?f=1&t=21061

Look at the MB Header:

Code: Select all

[BITS 32]
; This part MUST be 4byte aligned, so we solve that issue using 'ALIGN 4'
ALIGN 4
mboot:
    ; Multiboot macros to make a few lines later more readable
    MULTIBOOT_PAGE_ALIGN   equ 1<<0
    MULTIBOOT_MEMORY_INFO   equ 1<<1
    MULTIBOOT_AOUT_KLUDGE   equ 1<<16
    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)
;    EXTERN code, bss, end

    ; This is the GRUB Multiboot header. A boot signature
    dd MULTIBOOT_HEADER_MAGIC
    dd MULTIBOOT_HEADER_FLAGS
    dd MULTIBOOT_CHECKSUM
   
    ; AOUT kludge - must be physical addresses. Make a note of these:
    ; The linker script fills in the data for these ones!
    dd mboot
    dd code ;DOESN'T WORK	
;    dd $$   ;WORKS!
    dd bss
    dd end
    dd start

that was it. that should point to the mboot start too. instead of the .text section. I guess it really should be added to the wiki.

Another way to do exactly the same thing (and actually this is what I'm currently using) is to set the correct "code" address in the linker script:

Code: Select all

OUTPUT_FORMAT("elf32-i386")
ENTRY(start)
phys = 0x00100000;
SECTIONS
{
   /*
    * http://wiki.osdev.org/Grub_Error_13
    */
   . = phys;
   /* .__mbHeader will begin @ 'phys' */
   .__mbHeader : AT ( ADDR( .__mbHeader ) ) {
      mboot = .;
      code = .;
      *(.__mbHeader)
   }
  .text : AT(ADDR(.text)) {
    /*code = .;*/
    *(.text)
    *(.rodata)
    . = ALIGN(4096);
  }
  .data : AT(ADDR(.text) + (data - code))
  {
    data = .;
    *(.data)
    . = ALIGN(4096);
  }
  .bss : AT(ADDR(.text) + (bss - code))
  {
    bss = .;
    *(.bss)
    . = ALIGN(4096);
  }
  end = .;
}

thank you so much to everyone. REALLY. you have been really kind.

OSDev.org

"Error 13: Invalid or unsupported executable format" error

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Re: "Error 13: Invalid or unsupported executable format" error

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