thank you for telling me so much. i use ./MAKEDEV hd3 settrans -cp /cdrom /hurd/isofs /dev/hd3 to set my cdrom, and it can't mount by: mount /cdrom it tells me unknown filesystem or device but i can cd into /cdrom and do every things normally. but the next time i boot hurd , it can't be used whatever i try (such as mount or boot with the cd in the cdrom ,etc) how can i do?