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 run
dpkg-reconfigure and select
the Linux partition as the destination for GRUB. Funnily
enough, it didn't suffice to just run
as most people on the net speak of.