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

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 17.03.2011 19:40, Lennart Sorensen wrote:
> On Thu, Mar 17, 2011 at 05:29:51PM +0100, Vladimir 'φ-coder/phcoder' 
> Serbinenko wrote:
>   
>> On 17.03.2011 17:09, Lennart Sorensen wrote:
>>     
>>> 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.
>>>
>>>   
>>>       
>> Another wild guess:
>> @@ -506,6 +520,8 @@ get_safe_sectors (grub_disk_addr_t secto
>>    grub_size_t size;
>>    grub_uint32_t offset;
>>  
>> +  return 1;
>> +
>>    /* OFFSET = SECTOR % SECTORS */
>>    grub_divmod64 (sector, sectors, &offset);
>>     
> No go either.
>
>   
Can you dump complete drp before and after every call?

(19:52:44) phcoder: cjwatson: may the Lennart's last message be caused
by 4K sectors?(idk if he has 512B or 4K sectors)
(19:56:14) cjwatson: possible; he can find out by printing
drp->bytes_per_sector after the call to
grub_biosdisk_get_diskinfo_int13_extensions in
grub-core/disk/i386/pc/biosdisk.c
(19:56:25) cjwatson: at least find out what the BIOS thinks
> Here is what I see with some more debugging:
>
> [snip]
> int13_ext call: ah=42, drive=80, dap=   6fe00 (len=16 rsvd=0 blks=1 
> buf=1744830464 sec=2078)
> int13_ext call: ah=42, drive=80, dap=   6fe00 (len=16 rsvd=0 blks=1 
> buf=1744830464 sec=2079)
> int13_ext call: ah=42, drive=80, dap=   6fe00 (len=16 rsvd=0 blks=1 
> buf=1744830464 sec=72091664)
> failed int13_ext call: ah=42, drive=80, dap=   6fe00 returned eax=8000
> error: hd0 out of disk.
> Entering rescue mode...
> grub rescue>
>
> Now it has no excuse for failing a call for sector 72091664 when the
> drive has 156000000 or so sectors.
>
> I imagine if I made a small boot partition (less than 8G), the stupid
> thing would boot fine, but that's not acceptable on a brand new design.
> I am going to try resizing the partition as a test.
>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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