Why could installing LILO to MBR be unsafe?

nutthick · 11-25-2004, 05:05 AM

Why could installing LILO to the MBR be unsafe? I just had to do it to get Slask to boot and was curious.

Darin · 11-25-2004, 07:03 AM

Because it will overwrite any other operating system's bootup. In some Linux distributions you have to explicitly tell LILO (or grub) about your windows partition for it to be able to boot into, for others it will automatically check to see if you have windows and add that as an option on the bootup menu.

nutthick · 11-25-2004, 07:12 AM

So if the only OS I have installed is Linux then placing LILO onto the MBR isn't really a problem?

acid_kewpie · 11-25-2004, 07:19 AM

well only as much as messing with the MBR ever is. it's just generally a thing not to be taken lightly, that's all.

ror · 11-25-2004, 07:36 AM

it's basically there as a disclaimer

egag · 11-25-2004, 07:47 AM

When you install lilo, it will put a copy of the overwritten sector in " /boot/boot.nnnn.
( look in your /boot-dir, i have a file /boot/boot.0300 wich is 512 bytes long )
you can restore it by using the " -u " option or copy it with "dd"
( see " man lilo " ).

egag

nutthick · 11-25-2004, 08:48 AM

That makes sense as I was having boot problems and found a posting advising the following:

dd if=/dev/zero of=/dev/hda bs=512 count=1

which completely wiped the boot record.

egag · 11-25-2004, 08:54 AM

" dd if=/dev/zero of=/dev/hda bs=512 count=1 "

looks like a bad joke .
but you solved it now eh...

egag

nutthick · 11-25-2004, 09:04 AM

Worked perfectly. It totally wiped the MBR. I had installed RH and was switching back to Slack, but kept getting GRUB stopping the boot. Apparently RH wrote stuff to the MBR and even deleting all partitions with cfdisk wasn't getting rid of the data. Entering the dd command wiped all the partitions from the disk. Going back into cfdisk and there was just one undefined partition.

Guess it could be a bad joke if you had something to loose

egag · 11-25-2004, 09:52 AM

well...i didn't know what you prob. was before you used the command, but if you
really wanted to clean the mbr..... than it's a good adviice

egag