Backing up/restoring LILO

tntcoder · 05-27-2006, 01:48 PM

Hi,

I have lilo installed on the mbr of my hard drive, i need to install win xp as a dual boot on the same hard drive, when i install XP am i correct in assuming it will overwrite the MBR with its own bootloader?

So what i need to do is backup LILO/MBR and be able to restore it after XP is installed,

Is there any easy way to do this?

Thanks
Jack

btmiller · 05-27-2006, 03:23 PM

dd if=/dev/hda of=/path/to/backup bs=512 count=1

The MBR is just the first sector (512 bytes) of the hard drive. I'd back it up onto a floppy. Be careful with this -- if you get the if and of backwards, you'll nuke your MBR! An easier thing to do would be to install LILO itself onto a floppy and verify you can boot your Linux distro with it. Then go ahead, reinstall XP (it will indeed overwrite in the MBR). Then boot off of your boot floppy to get back into Linux and rerun the lilo command to reinstall LILO on the MBR (don't forget to add an entry to /etc/lilo.conf so it knows how to boot Windows too).

If you don't want to make a boot floppy, you can use the first Slack disk as a rescue disk IIRC. You could also boot off a LiveCD, mount your Linux partition, chroot into it, and rerun lilo from the chroot encironment.

DrEwMoNeY · 05-27-2006, 03:24 PM

I tried to do the same thing once. In the end, I ended up wiping the drive clean, install XP, and then Slack.

I think if you just run LILO after installing XP, you might be alright. I hope your drive is partitioned for XP already!?!

jschiwal · 05-27-2006, 04:00 PM

The mbr is on the first 446 bytes. The rest contain the partition tables and the mbr signature.

From wikipedia:

Code:

 Address   Function
+---------------------------------------+
| 0x0000   Code Area (446 Bytes)        |
|=======================================|
| 0x01BE   16 byte partition table entry|
|=======================================|
| 0x01CE   16 byte partition table entry|
|=======================================|
| 0x01DE   16 byte partition table entry|
|=======================================|
| 0x01EE   16 byte partition table entry|
|=======================================|
| 0x01FE   2 byte MBR signature (0xAA55)|
+---------------------------------------+

If you create a rescue disk before setting up windows, then you can use it to boot into Linux and use lilo or grub to reinstall the mbr after adding an entry for windows which will be chain loaded.

An alternative is to change your boot entry to the root partition, run lilo or grub to write the bootstrap loader to the root partition, and use "dd if=<root device> of=linux.bin bs=446 bc=1" to write it to a file. Now save the "linux.bin" file on external media or a partition that windows can read so that you can save it to C:\ later on when Windows boots up.

After windows is installed, in windows edit the C:\BOOT.INI file to add an entry to the boot menu to chainload the lilo or grub boot loader.

Code:

[boot loader]
timeout=5
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows XP Professional" /fastdetect
c:\linux.bin="Linux"