Does making a partition bootable erase any data?

svar · 02-28-2010, 03:52 AM

Due to a mixup when installing another Linux on a different partition on the same disk(that is I had /dev/sdb1 ->Slack 13 and added /dev/sdb3->Ubuntu), making /dev/sdb3 bootable, lilo would not work. I think dev/sdb1 was bootable before and the reason lilo does not work is it is not bootable now. So if I use the Slack installation DVD and make /dev/sdb1 bootable, does it erase any data, as it warns?
For the record, here is lilo.conf

# Linux bootable partition config begins
image = /boot/vmlinuz
root = /dev/sdb1
label = Slack13
read-only # Partitions should be mounted read-only for checking
# Linux bootable partition config ends
image = /boot/vmlinuz-2.6.31-14-generic
root = /dev/sdb3
label =Karmic9.10
initrd=/boot/initrd.img-2.6.31-14-generic

I should add I can boot everything with grub of yet a 3rd linux distro I have, but I am just curious...

samac · 02-28-2010, 03:59 AM

Should be OK to use fdisk or cfdisk to make sdb1 bootable, but before you do, did you re-run lilo? Boot with the Slackware cd and then re-run lilo and see if that fixes the problem.

samac

pixellany · 02-28-2010, 09:10 AM

You do not need the set the "bootable" flag---Linux does not use it. Regardless, it is only a flag in the partition table--it does not affect your data.

svar · 03-01-2010, 12:44 AM

Yes, I di dre-run lilo. The problem with booting with the Slack DVD:
...login as root
mkdir /mnt
mount /dev/sdb1 /mnt/root
cd /mnt/root
Now one needs to run /mnt/root/sbin/lilo
which looks for lilo.conf in /etc while it is in /mnt/root/etc
Furthermore, images in /boot should read images in /mnt/root/boot
So
cp /mnt/root/etc/lilo.conf /etc/lilo.conf #/etc is in memory
but cp /mnt/root/boot/... stuff does not work(too big for memory?)
So I need to change lilo.conf to look for vmlinuz in /mnt/root/boot/...
Right?

samac · 03-01-2010, 02:09 AM

When you boot via the DVD you do not need to mount anything the DVD boots you into your system.

Quote:

Welcome to Slackware64 version 13.013 (Linux kernel 2.6.32.7)!

If you need to pass extra parameters to the kernel, enter them at the prompt
below after the name of the kernel to boot (huge.s etc).

In a pinch, you can boot your system from here with a command like:

boot: huge.s root=/dev/hda1 rdinit= ro

In the example above, /dev/hda1 is the / Linux partition.

This prompt is just for entering extra parameters. If you don't need to enter
any parameters, hit ENTER to boot the default kernel "huge.s" or press [F2]
for a listing of more kernel choices.

So you need to use

Quote:

huge.s root=/dev/sdb1 rdinit= ro

samac

allend · 03-01-2010, 02:09 AM

Quote:

So I need to change lilo.conf to look for vmlinuz in /mnt/root/boot/...
Right?

NO - Use the -r option to lilo i.e.
Boot from the Slackware 13 install disk and continue until after selection of a keyboard and you have a root login. Then:
'mkdir /mnt/tmp' - Note: you had mkdir /mnt, but that directory already exists. Create a new subdirectory.
'mount /dev/sdb1 /mnt/tmp'
'/mnt/tmp/lilo -r /mnt/tmp'

[edit] samac's way is better [/edit]

trryhend · 03-01-2010, 03:02 AM

samac is correct. Your problem is that you did not chroot to the system and therefore lilo will not work properly. Boot as samac suggested and try again, (you'll see the instructions on the screen.)