[Cialug] Grub Error 18

[Zachary Kotlarek]

On Mar 30, 2008, at 5:20 AM, Deepan wrote:
> Hi All,
> I have installed Fedora on Macbook. It works fine
> when I boot it in native mode. However, when I
> boot it via parallels, I get the following error.
> Error 18: Selected cylinder exceeds maximum
> supported by BIOS.  I do understand that this
> error is thrown when Grub tries to read an address
> beyond the end of BIOS translated area. Is this a
> problem with Grub or BIOS ? My boot partition is
> the first partition.

Officially that error means that you're booting a drive over 1024  
cylinders in CHS mode, and that you should turn LBA mode on. But  
assuming you've got a motherboard less than 100 years old, and/or have  
already turned on LBA mode:

Check that you're reading GRUB off the drive you think you are -- the  
system will read the MBR off the first drive that has one based on the  
BIOS boot order you selected. A common culprit here is USB drives, as  
the BIOS may be set to boot from removable drives first, but USB  
drives are unlikely to show up as /dev/xda after booting. This is one  
of the reasons it's recommended that you install GRUB in BIOS mode  
rather than after booting, because once booted GRUB can't always tell  
what the BIOS drive order will be.

Also some SCSI cards are known to have bad INT 13 support, which  
requires that you *disable* INT 13/LBA for the SCSI drive and boot out  
of the first 1024 cylinders. Again this is mostly and issue in older  
systems that assumed CHS mode by default, but if you've got a SCSI  
card it's worth checking.

Or you could convince the consumer motherboard world to stop with this  
ridiculous BIOS thing and install a pre-boot environment that's less  
than 27 years old and actually supports named drive trees and can be  
extended to read actual file systems, at which point grub would be  
largely unneeded. But that may take more time and effort than you're  
willing to put into fixing a bootloader problem.

	Zach
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