[lug] grub.conf and BIOS drive specifications

Lee Woodworth blug-mail at duboulder.com
Mon Oct 17 12:05:41 MDT 2005

D. Stimits wrote:
> ...
>> You can work around it by having a separate boot partition on IDE0, 
>> install
>> grub to that. Keep the BIOS boot order as IDE,SCSI and have the BIOS 
>> always
>> boot to the IDE0 boot partition. Then you have several sections in the
>> grub.conf on IDE0. Keep all the kernel and system map files in the boot
>> partition.
> ...
> Unfortunately I can't do that...the IDE and the SCSI are all removeable. 
> The IDE works as a rescue and test system, and as a big floppy. The scsi 
> is more likely to be used as a /boot/, but unfortunately sometimes 
> experimentation means the one with the /boot/ gets yanked as well.
> Is there no way to query the bios to find out what hex value it thinks 
> each drive is? If I could query it maybe I could figure out a workable 
> combination. I know there is a config option to assign a given bios hex 
> value (like 0x80) to be hd0 or hd1 or whatever...but I don't know how to 
> find this information on this system, and I'm not willing to risk 
> harming it. I'm starting to think of switching back to LILO, but I'm not 
> sure that'd be any better...grub is certainly a lot less of a pain for 
> many things.
Grub doesn't care about the absolute numbers. It scans the drives the
BIOS reports as present, in the order the BIOS reports them. So if IDE0
is not present grub won't count it. You have to use BIOS facilities to
affect how the BIOS reports the IDE drives. Don't know what happens if
the BIOS reports a drive that grub can't actually talk to.
> D. Stimits, stimits AT comcast DOT net
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