fs_romdisk is the primary method by which one builds files into a program image in KOS (faster loading, easy for debugging, etc). A romdisk image is generated using the program genromfs; this image is converted to a binary object and linked with the program. The KOS initialization sets up fs_romdisk to point to this image. Any number of arbitrarily structured directories and files are also possible in fs_romdisk.
fs_romdisk mounts itself on /rd on the tree.