Dual Boot with a twist.

PirateFSM · 07-10-2006, 07:31 AM

Hey guys,

Thank you for taking the time to read this.

I have one disk with XP installed, and one with FC5. I installed FC5 first and have had it for a while, and had a sudden need for an XP install. As of right now the only way i can boot the linux partition is via BIOS selection. My Linux disk is sda and my windows disk is hda. I don't know how this corresponds to hd0 and the like. I have tried grub-install /dev/sda already and it doesn't read my hda for some reason. Some help with probing or a point in the right direction would be great. I have three disks total. sda,sdb,hda. Thank you!

pixellany · 07-10-2006, 08:07 AM

for GRUB to boot your system, it has to be on the first drive--in the mbr. This is where the BIOS goes first.

(I think) that the grub numbering corresponds to the boot order in the BIOS.

A simple way to test things is make a grub boot floppy, and manually boot your OSes. This will confirm what **GRUB** thinks the correct number are. See the GRUB manual for details on how to boot from the floppy.

xpromisex · 07-10-2006, 08:10 AM

So you have an IDE drive with Windows XP on it and a SATA drive with FC5? The windows install boots normally but you have to choose to boot from the SATA drive to get linux at all, am I right?

If so, all you need to do is install GRUB in the MBR of the first harddrive (the 'Primary Master'), and add the lines to GRUB's menu.lst. To add those lines to GRUB, copy the contents of the menu.lst out (so you don't mess up booting your FC5 install) and when you need to add your Windows install to the menu.lst, it is something like this:

Code:

title Windows XP 
rootnoverify (hd0,0)
chainloader +1

The rootnoverify line is the one that will change. (hd0,0) is the first partition on the first harddisk, (hd2,1) is the first partition on the third harddisk etc.

If this is too confusing, let me know. Good luck!

Edit: pixellany beat me too it, but this is a bit more explicitive so I will leave it here.