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

[Lennart Sorensen]

On Wed, Mar 16, 2011 at 11:16:05PM +0100, Vladimir 'φ-coder/phcoder' Serbinenko 
wrote:
> It's not really a fixup. Correct return on no error is CF=0 AH=0. Some
> BIOSes in some other functions returned CF=0, AH!= 0 on no error so it
> was a wild guess.
> > Failed int13_ext call: ah=42, drive=80, dap=   6fe00 returned eax=8000
> >   
> Error 0x80 according to
> http://www.delorie.com/djgpp/doc/rbinter/it/34/2.html means timeout.
> Following code would retry on timeout:
> === 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 22:13:12 +0000
> @@ -72,6 +72,8 @@
>  grub_biosdisk_rw_int13_extensions (int ah, int drive, void *dap)
>  {
>    struct grub_bios_int_registers regs;
> +  int tries = 4;
> + retry:
>    regs.eax = ah << 8;
>    /* compute the address of disk_address_packet */
>    regs.ds = (((grub_addr_t) dap) & 0xffff0000) >> 4;
> @@ -80,6 +82,16 @@
>    regs.flags = GRUB_CPU_INT_FLAGS_DEFAULT;
>  
>    grub_bios_interrupt (0x13, &regs);
> +  if (!(regs.flags & GRUB_CPU_INT_FLAGS_CARRY))
> +    return 0;
> +
> +  if (((regs.eax >> 8) & 0xff) == 0x80 && tries)
> +    {
> +      grub_millisleep (10);
> +      tries--;
> +      goto retry;
> +    }
> +
>    return (regs.eax >> 8) & 0xff;
>  }

So that didn't make any difference to it.

It just keeps returning 0x8000 in eax on every retry.

I really want to find out what this BIOS is doing wrong so I can tell
the system maker what to fix.

I am going to add some debuging to find out what is in the dap being
passed to the BIOS.

-- 
Len Sorensen