Grub and PE based Kernels

[Solar]

As for the cross-compiler error, are you sure you used the command line options as described in the FAQ page? That looks like you forgot the --without-headers part... I don't have the Cygwin sources downloaded, but I'll try to verify later.

As for the global variables... are you sure your linker script / loader / whatever included your .data section? That's where global variables end up... (read, if you post your code, don't forget the linker script...)

[srg]

I'll try it again just in case

well, here is my linker script, it is modified from Tim's Mobius which was modified from cygwins linker script.

/*
* SG-OS kernel linker script: kernel.ld
* Modified from The Mobius kernel.ld
* Which was modified from Cygwin's i386pe.x
*/

OUTPUT_FORMAT(pei-i386)
SECTIONS
{
_scode = __image_base__;
.text __image_base__ + __section_alignment__ :
{
*(.init)
*(.text)
*(SORT(.text$*))
*(.glue_7t)
*(.glue_7)
___CTOR_LIST__ = .; __CTOR_LIST__ = . ;
         LONG (-1); *(.ctors); *(.ctor); LONG (0);
___DTOR_LIST__ = .; __DTOR_LIST__ = . ;
         LONG (-1); *(.dtors); *(.dtor); LONG (0);
*(.fini)
/* ??? Why is .gcc_exc here? */
*(.gcc_exc)
etext = .;
*(.gcc_except_table)
}
/* The Cygwin32 library uses a section to avoid copying certain data
on fork. This used to be named ".data". The linker used
to include this between __data_start__ and __data_end__, but that
breaks building the cygwin32 dll. Instead, we name the section
".data_cygwin_nocopy" and explictly include it after __data_end__. */
.data BLOCK(__section_alignment__) :
{
__data_start__ = . ;
*(.data)
*(.data2)
*(SORT(.data$*))
__data_end__ = . ;
*(.data_cygwin_nocopy)
}
.rdata BLOCK(__section_alignment__) :
{
*(.rdata)
*(SORT(.rdata$*))
*(.eh_frame)
}
.pdata BLOCK(__section_alignment__) :
{
*(.pdata)
}
.edata BLOCK(__section_alignment__) :
{
*(.edata)
}
/DISCARD/ :
{
*(.debug$S)
*(.debug$T)
*(.debug$F)
*(.drectve)
}

/*
* SG-OS kernel: The kernel doesn't import anything.
* We save 4096 bytes by omitting these five zeroes.
*/
.idata BLOCK(__section_alignment__) :
{
/* This cannot currently be handled with grouped sections.
   See pe.em:sort_sections. */
SORT(*)(.idata$2)
SORT(*)(.idata$3)
/* These zeroes mark the end of the import list. */
LONG (0); LONG (0); LONG (0); LONG (0); LONG (0);
SORT(*)(.idata$4)
SORT(*)(.idata$5)
SORT(*)(.idata$6)
SORT(*)(.idata$7)
}

.CRT BLOCK(__section_alignment__) :
{
*(SORT(.CRT$*))
}
.endjunk BLOCK(__section_alignment__) :
{
/* end is deprecated, don't use it */
end = .;
_end = .;
__end__ = .;
_edata = .;
}
.rsrc BLOCK(__section_alignment__) :
{
*(.rsrc)
*(SORT(.rsrc$*))
}
.reloc BLOCK(__section_alignment__) :
{
*(.reloc)
}
.stab BLOCK(__section_alignment__) (NOLOAD) :
{
[ .stab ]
}
.stabstr BLOCK(__section_alignment__) (NOLOAD) :
{
[ .stabstr ]
}
.bss BLOCK(__section_alignment__) :
{
__bss_start__ = . ;
   _sbss = .;

   /*
    * Added stack and kernel page directory.
    * These are in the linker script to ensure alignment and size:
    *   it is vital that the page directory be page-aligned.
    */

   _stack = .;
   . += 8192;
   _stack_end = .;
   _kernel_stack_end = .;

   _arch_df_stack = .;
   . += 4096;
   
   . = ALIGN(4096);
   _kernel_pagedir = .;
   . += 4096;
   
*(.bss)
*(COMMON)

   . = ALIGN(4096);
   _ebss = .;
__bss_end__ = . ;
}
}

[srg]

I definatly did enter the command line for the cross compiler as said in the FAQ, except I used i386-elf.

BTW, would a linker script for an elf kernel be a lot simpler that the standard cygwin based thing I have above??

[Solar]

*rollingonthefloorlaughing*

Here's the one I use with my Cygwin-based cross-compiler - although I have to admit that my kernel does preciously little ATM (read, the linker script might grow):

Code: Select all

ENTRY (kernel_loader)

SECTIONS
{
    . = 0x00100000;

    .text :
    {
        *(.text)
        *(.rodata)
    }

    .data ALIGN (0x1000) :
    {
        start_ctors = .;
        *(.ctor*)
        end_ctors = .;
        *(.data)
    }

    .bss :
    {
        _sbss = .;
        *(COMMON)
        *(.bss)
        _ebss = .;
    }
}

[srg]

there's not much I can say to that heh

what is .ctor BTW

Oh yes, Lets get that cross compiler working!!

Could the trouble be because I'm using the source that came with cygwin.

[Solar]

what is .ctor BTW

I'm using C++ as language. .ctor* is a list of pointers pointing to the constructors of global / static data objects, which I have to call from my assembly bootstrap code before I can use them in my C++ main().

Could the trouble be because I'm using the source that came with cygwin.

That's possible; I've never tried the Cygwin source.

[srg]

Right I've just tried to compile a cross compiler with downloaded (non cygwin) sources and I get exactly the same error!!!!

Is there anything that I sould or shouldn't install when I install cygwin??

[Solar]

Please give more information, as I am unable to reproduce the error:

* what version of binutils and gcc are you using? (Version used for building, and version of the sources to be build)
* which commands have you used to compile the stuff? Exactly as in the tutorial, or did you omit / change / add some options?

I really want that tutorial to be correct...

[srg]

Sure, I also want a cross compiler

I'm building with gcc version 3.3.1 (cygming special)
and binutils 2.14.90 20030901

The sources I'm using are: gcc version 3.3.1 and binutils-2.14 (downloaded seperately)

The only thing on the command line that I have changed is the TARGET, I'm using i386-elf.

BUT I have tried i586-elf and I get the same error!

BTW The last time I tried to make a cross compiler, I gave up after over a week of trying.

Please could you give me a list of all the packages that you install when installing cygwin, as that could be that cause of the problem. Maybe I'm missing one?

[Solar]

D'oh... I got the same error with the 3.3.1 sources - the 3.3 sources worked fine. :-\

Oh, how I love the stability of the Open Source...

[Pype.Clicker]

@solar: and i'm still sticking on gcc-2.95.3 for that kind of reasons ;-P

[Solar]

...basically a non-option if you're after C++ - much too much improved from 2.95 -> 3.3...

[Solar]

Damnit, looks like I have used --with-newlib when configuring my cross-gcc, but didn't state so in the Wiki page.

I don't have time left to verify this today; maybe you can try it, srg?

[srg]

Damnit, looks like I have used --with-newlib when configuring my cross-gcc, but didn't state so in the Wiki page.

I don't have time left to verify this today; maybe you can try it, srg?

Will do

Actually, I've seen on a site showing how to make a sparc cross compiler they used this --with-newlib switch

what is newlib?

Anyway, about to test

[nullify]

Building a cross-compiled version of GCC 3.3.1 as per your instructions worked without any problems for me...

Code: Select all

$ i686-elf-gcc --version
i686-elf-gcc (GCC) 3.3.1 (cygming special)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

It might not be entirely related to the version of GCC.