Windows Overwrites the linux boot sector when i install it

yubyub · 07-29-2006, 10:40 PM

whenever i install windoes in a comuter with linux installed i overwrits the linux and makes linux unacssesable
can someone plese tell me what to do

AAnarchYY · 07-29-2006, 10:43 PM

thats just what windoze does, you will need to configre a bootloader(lilo,grub) to give you a choice, i belive that has been covered.

konsolebox · 07-29-2006, 11:00 PM

in simplest ways, boot to your livecd then do 'mount /dev/hdaX /mnt/anydir; chroot /mnt/anydir /bin/bash' then reinstall grub or lilo there

Edit: check out this thread: http://www.linuxquestions.org/questi...d.php?t=319076

jiml8 · 07-30-2006, 09:03 PM

Windows will overwrite your master boot record. You can't stop it from doing this. After it overwrites your mbr, you can't access anything but Windows.

But with a bit of preparation you can protect yourself. The easiest way is to use the dd command in linux to make a backup of your mbr.

Thus, if your boot drive is hda, you enter this line:

dd if=/dev/hda of=~/bootblockbackup.bin bs=512 count=1

This will copy your mbr to a file called bootblockbackup.bin in your home directory.

Now install windows.

Then, use a Linux boot floppy, or a live CD to start Linux. Go to your home directory and type in this command:

dd if=bootblockbackup.sh of=/dev/hda

This will rewrite your bootblock to the way it was before. Now your problem is that you won't be able to access Windows.

If you are using lilo, I don't know how you fix that. I use grub and in grub you would go to your /boot/grub directory and add lines like this to the file menu.lst:

Code:

title Windows
root (hd0,0)
chainloader +1

These lines assume that your Windows is on drive 0 (hda) partition 0 (hda1). If Windows is someplace else, modify the root line accordingly.

syg00 · 07-30-2006, 09:37 PM

Peronally I reckon the re-install of the loader is a better option.
If you happen to allocate new (or change) partitions during the 'doze install, you really wouldn't want to be restoring that first sector.

anubis26 · 08-04-2006, 10:47 AM

Usually when setting up a configuration like that, I try to install windows before linux, then everything is OK.

Daws · 08-04-2006, 09:43 PM

Way I do it is to have a grub floppy disk lying around, if you use grub there should be a "grub-floppy" command somewhere (usually in sbin directories).

Code:

grub-floppy /dev/fd0

will create the disk for you.

Now boot the computer with the disk. In this example /boot/grub is on (hd0,0).

Once you are at the grub prompt:

Code:

root (hd0,0)
setup (hd0,0)

The loader will be installed and configured as before, at this point you need to add entries for windows in menu.lst or grub.conf.