grub error 18

Christopher Chan christopher.chan at bradbury.edu.hk
Mon Sep 21 08:07:42 UTC 2009


David Kuntadi wrote:
> On Mon, Sep 21, 2009 at 2:06 PM, Christopher Chan
> <christopher.chan at bradbury.edu.hk> wrote:
>   
>> When I reinstall grub in the LiveCD environment and then reboot the
>> machine to let it boot up the installed Jaunty, there is no problem.
>> That demonstrates that there is no 1024 cylinder problem even though
>> this is an older machine. However, that grub installation that I did
>> from the LiveCD environment is apparently being overwritten whenever I
>> shutdown since I get the weird error 18 message from grub on the next
>> attempt to boot.
>>     
>
> Is there any proof/clue so that you think it is overwritten? I still
> guess that the bios read the partition differently after upgrade, but
> not sure why. I have not have this issue so far after using uuid.
>   
The installed grub from the LiveCD had no problems without having to 
muck about with the BIOS.

If that was not overwritten during a shutdown, then I should have no 
grub error 18 problems.
> But to confirm that it is not what I suspected, could you check
> /etc/fstab before and after reinstall Grub.
> In additio to that, do:
> Before reinsall:
> ls -n /dev/disk/by-uuid > before.txt
>
> After resintall:
> ls -n /dev/disk/by-uuid > after.txt
>
> And compare before.txt. and after.txt if there is any change.
>   
One single IDE drive. I doubt very much that there will be any change at 
all.


> As you do not  think it is location of the kernel:
> Quoted what you wrote:
>   
>> grub cannot even load stage1.5 when it is error 18...i don't think it is
>> anything to do with the location of the kernel.
>>     
>
> Please see below writing:
>
> http://wiki.linuxquestions.org/wiki/GRUB#Error_18
> Error 18
>
> Error 18: Selected cylinder exceeds maximum supported by BIOS
>
> This error is returned when a read is attempted at a linear block
> address beyond the end of the BIOS translated area. This generally
> happens if your disk is larger than the BIOS can handle (512MB for
> (E)IDE disks on older machines or larger than 8GB on others.). In more
> practical terms this means the BIOS is unable to start executing the
> kernel because the kernel is not located within the block it can
> access at boot up time.
>
> Read more: http://wiki.linuxquestions.org/wiki/GRUB#Error_18#ixzz0RirBktG7
>   


Yeah, yeah. However, what you do not know is that you get this 'error 
18' without even seeing the grub menu. If I saw this 'error 18' after I 
saw the grub menu, fine. But that is not what I saw. Besides, the 
explanation of error 18 from grub docs say this:

18 : Selected cylinder exceeds maximum supported by BIOS
     This error is returned when a read is attempted at a linear block
     address beyond the end of the BIOS translated area. This generally
     happens if your disk is larger than the BIOS can handle (512MB for
     (E)IDE disks on older machines or larger than 8GB in general).

It does not say that it happens when it is trying to read the kernel 
into memory. The wording here shows that ANY attempt to read something 
beyond BIOS limits will end in error 18. That will apply to all the 
possible files grub stage1 tries to read: stage1.5, stage2. The 
explanation in the url is misleading at best.




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