Carlos M. Martinez-Cagnazzo

If you are like me, chances are that you could not resist the urge to download and install Microsoft's public beta of the upcoming Windows 7 release.

So, I did install it at the expense of having my Fedora 10 GRUB overwritten by Windows 7's installer. Although W7 works fine now, I lost the ability to boot into FC10.

I booted the laptop using my FC 10 LiveCD and tried to do the mount root / chroot / grub-install routine that is described everywhere in the Internet, but I found that the chrooted system has no devices under /dev and this makes grub-install fail.

I went in circles for about half an hour until I came up with a solution: Use mount's "--bind" option to remount the LiveCD's /dev under the chrooted system's /dev.

So the whole procedure goes like this:

• Boot and log into your FC10 LiveCD
• Open a terminal and "su -" into the root account
• Mount the root filesystem, mine was /dev/sda6 under /mnt/root (or whatever you like)
  • mount /dev/sda6 /mnt/root
• Mount /proc
  • mount -t proc proc /mnt/root/proc
• Copy /proc/mounts to mtab
  • cat /proc/mounts > /mnt/root/etc/mtab
• Bind /dev to /mnt/root/dev (this makes devices visible to grub in chrooted environment)
  • mount --bind /dev /mnt/root/dev
• Chroot
  • chroot /mnt/root /bin/bash
  • source /etc/profile
• Re-install GRUB
  • grub-install --recheck "(hd0)"

And voilá! Happy booting!