Re-writing Linux to the MBR
 

Hi there,

I have a dual boot system, Linux RH9 and WinXP Home, I want to change to WinXP Pro, but if I install it, it will rewrite the MBR, and I'll only be able to access Linux through my boot disk...

How can I rewrite Grub to the MBR? Is it possible?

Thanks for your help! :)

Yep its possible. Boot with your boot disk. Get to a console and as root type:

grub
--wait a while as it probles the bios--
root(hdx,x) --Your /boot partition or / if you haven't got a boot partition--
setup(hd0)
quit

Now reboot and everthing should be back in order.

Great stuff! Thanks so much for your help! :)

I'm about to install win2k and run dualboot. But how do i make a bootdisk in linux? Oh, and one more thing... I use lilo, how do i rewerite the MBR then? The same way as grub?

To make a boot floopy for your machine ( And it will ONLY work for your machine ) go into /etc/lilo.conf and comment out the line boot=/dev/hda and add the line boot=/dev/fd0 So it looks like this:

#boot=/dev/hda
boot=/dev/fd0

Now save it. Put a blank floppy in and as root type /sbin/lilo. This will create your boot floopy. Don't forget to change things back after its finished.

To restore LILO to the MBR simply execute /sbin/lilo again. Allthough you will need to alter the lilo.conf for you new OS.

Another way to make a boot floppy is at the command line type mkbootdisk kernel version and your good to go.Of course substitute kernel version for your own actual kernel version.

mkbootdisk can also be mkboot, but its implentation varies quite a bit. If it exists at all.

I did what you said leonscape, with the bootdisk, but when i checked the floppy after i'd typed "/sbin/lilo", there was nothing on the disk. I'm just wondering if that's correct ;)

Usually, Its simply written the first block of the disk as a bootloader. Try Booting with it. ( Which you should always do to make sure boot disks works, I've been burned by bad disks ).

Conversely,

In case I remove linux from my system, is it possible for me to remove LILO from the MBR? and if yes, then how?

You sure can, in windows type "fdisk /mbr" without the quotes, and you should be good to go.

Thanks very much, I used the FIXMBR from the recovery console, and it worked too !!