etc/crypttab.m4

   1 # <target name> <source device> <key file> <options>
   2 VM_LVM_LV`'_root_deciphered /dev/VM_LVM_VG/VM_LVM_LV`'_root none                        luks,lvm=VM_LVM_VG
   3 VM_LVM_LV`'_var_deciphered  /dev/VM_LVM_VG/VM_LVM_LV`'_var  VM_LVM_LV`'_root_deciphered luks,lvm=VM_LVM_VG,keyscript=/lib/cryptsetup/scripts/decrypt_derived
   4 VM_LVM_LV`'_home_deciphered /dev/VM_LVM_VG/VM_LVM_LV`'_home VM_LVM_LV`'_root_deciphered luks,lvm=VM_LVM_VG,keyscript=/lib/cryptsetup/scripts/decrypt_derived
   5 VM_LVM_LV`'_swap_deciphered /dev/VM_LVM_VG/VM_LVM_LV`'_swap VM_LVM_LV`'_root_deciphered luks,lvm=VM_LVM_VG,keyscript=/lib/cryptsetup/scripts/decrypt_derived