You need to create an menu.lst file in /boot/grub, with something that looks like this (replace the "..." with you know what) if you do not want to retype the lines by hand all the time: timeout 30 default 0 title Debian GNU/Hurd root (hd1,0) kernel /boot/gnumach root=device:hd0s1 module /hurd/ext2fs.static ... module /lib/ld.so.1 /hurd/exec $(exec-task=task-create)