When upgrading my Mac OS X to Snow Leopard, OS X took the liberty of wiping out both my refit boot loader and may (chain) loader GRUB on the Linux partition. When booting Linux after the refit screen, I got a "Unknown file system" error.
The remedy was to boot with a Linux live CD (I used systemrescuecd),
chroot into the Linux partition and run
dpkg-reconfigure on the GRUB package:
First, I found the name of my Linux partition by running:
# fdisk -l /dev/sda
I found it to be/dev/sda4 and could proceed
with the command line magic:
# mkdir /mnt/debian
# mount /dev/sda4 /mnt/debian
# mount -o bind /dev /mnt/debian/dev
# mount -o bind /sys /mnt/debian/sys
# mount -o bind /proc /mnt/debian/proc
# chroot /mnt/debian
# dpkg-reconfigure grub-pc
The crux was to rundpkg-reconfigure and select
the Linux partition as the destination for GRUB. Funnily
enough, it didn't suffice to just runupdate-grub
as most people on the net speak of.
