Re: How to debug 'out of disk' error.

[Lennart Sorensen]

On Wed, Mar 16, 2011 at 04:29:32PM +0100, Vladimir 'φ-coder/phcoder' Serbinenko 
wrote:
> On 16.03.2011 16:13, Lennart Sorensen wrote:
> > I am trying to figure out why grub2 (from Debian Squeeze) gives an 'out
> > of disk' error when trying to boot from the HD after doing an install.
> > It ends up at a grub rescue prompt, given it can't even read the disk
> > well enough to load the full grub.  Doing ls shows the disks, and I can
> > show the root directory of a partition, but anything further seems to
> > hit the same 'out of disk' error.
> >
> >   
> ls -l should show how big it thinks the disk is. Compare it with its
> real size
> > The system is a Compulab CM-iTC which uses an intel tunnelcreek atom
> > (the new one) with a phoenix bios.  So far Compulab's response when told
> > it won't boot grub2 was "We know, but syslinux works fine.", which to
> > me is not a solution at all.  The same system also hangs the Linux 2.6.32
> > kernel unless 'edd=off' is added to the kernel command line.
> >
> >   
> Looks like int13 is borked. Perhaps it's borked in a way which prevents
> GRUB from detecting 13/42 function. You can try to force int13/42 by:
> === modified file 'grub-core/disk/i386/pc/biosdisk.c'
> --- grub-core/disk/i386/pc/biosdisk.c    2011-01-04 14:42:47 +0000
> +++ grub-core/disk/i386/pc/biosdisk.c    2011-03-16 15:28:26 +0000
> @@ -145,6 +145,8 @@
>  {
>    struct grub_bios_int_registers regs;
>  
> +  return 1;
> +
>    regs.edx = drive & 0xff;
>    regs.eax = 0x4100;
>    regs.ebx = 0x55aa;

So I now have some debug info:

version=48
total_sectors=156312576 C=16383 H=16 S=63
error: hd0,msdos1 out of disk.
Entering rescue mode...
grub rescue>

So version is returning something, and it is actually getting the disk
size properly.  I wonder what else could cause the out of disk message
then.

-- 
len Sorensen