Grub - how to point to my CD-ROM drive?

ngomong · 06-13-2002, 05:08 PM

I'm trying to go dual-boot... adding a Win disk to my Linux system.

I'm following the directions laid out in the Grub + Win9x HOW-TO.

My question is, how do I tell grub to point to my cdrom-drive, instead of a floppy, for the boot disk? This is the part of the grub.conf file I need to edit:

Code:

title DOS Boot Disk
	map (hd0,0) (hd0,2)
	map (hd0,2) (hd0,0)
	chainloader (fd0)+1

Furthermore, my CD-ROM drive is on the SCSI chain.

DavidPhillips · 06-13-2002, 07:08 PM

if it's on the primary slave it's hd0, 1

ngomong · 06-13-2002, 08:50 PM

Actually, if it were primary slave, wouldn't it be (hd1,0)?

Also, my drive is on the SCSI chain... would it perhaps be scd0?

DavidPhillips · 06-13-2002, 09:03 PM

right, I had it backwards. the first number is the drive number

the second is the partition number

DavidPhillips · 06-13-2002, 09:19 PM

it appears that grub does not distinguish between scsi and ide, so the first drive is hd0, 0 if it's hda1 or sda1

maybe you can use

kernel root=/dev/sda1

or whatever it is

i guess it depends on the bios setup

ngomong · 06-13-2002, 09:33 PM

Yeah, but it's a CD-ROM drive...

I tried sd0, sr0, scd0, etc...

I'll keep trying different things.

linuxcool · 06-13-2002, 10:10 PM

Unless things have changed, grub doesn't recognize a cdrom drive as bootable. So, you can't assign drive number.

Quote:

The device.map file.

This file is used by grub to map GRUB based drive names to the Linux counterparts. An example of this file would be:

(fd0) /dev/fd0

(hd0) /dev/hda

(hd1) /dev/hdb

(hd2) /dev/hdc

(hd3) /dev/sda

(hd4) /dev/sdb

In this example, the system has the CD-ROM located at /dev/hdd (IDE secondary slave). You will notice that it is not listed in the device.map file. CD-ROMS are not listed as GRUB does not consider them to be a boot capable hard drive. The device.map file will only list the drives that were installed when the OS was installed. If, for example, you changed the order of the drives (swapped primary master and slave drives for example) or added another hard drive to the system, this file may need to be edited to reflect those changes.

I got that from here.

When you designate a drive it's hd0 or hd1. hd0,0 refers to the first partition on the hd0 drive. Also, when grub assigns drive numbers it will skip over nonbootable drives and empty connections on the ide channels. Example. If you have a hard drive on the primary master and the secondary slave and a cdrom drive on primary slave and nothing on secondary master, the primary master will be hd0 and the secondary slave will be hd1. The cdrom drive and the empty connection are assigned no number.