Usage:
 mkfs.cramfs [options] dirname outfile

Make a compressed ROM file system.

 dirname        root of the filesystem to be compressed
 outfile        output file

Options:
 -v             be verbose
 -E             make all warnings errors (non-zero exit status)
 -b blksize     use this blocksize, must equal page size
 -e edition     set edition number (part of fsid)
 -N endian      set cramfs endianness (big|little|host), default host
 -i file        insert a file image into the filesystem
 -n name        set name of cramfs filesystem
 -p             pad by 512 bytes for boot code
 -z             make explicit holes
 -l[=<mode>]    use exclusive device lock (yes, no or nonblock)

 -h, --help     display this help
 -V, --version  display version

For more details see mkfs.cramfs(8).