newfs_sysvbfs —
construct a new System V Boot File System
  
    | newfs_sysvbfs | [ -FZ] [-ssectors] special | 
newfs_sysvbfs builds a System V boot file system on the
  specified special. If it is a device, the size information will be taken from
  the disk label and before running newfs_sysvbfs the
  disk must be labeled using
  disklabel(8); the proper
  fstype is “SysVBFS”. Otherwise, the size must be specified on
  the command line.
The following arguments are supported:
  - -F
- Create file system to a regular file.
- -ssectors
- Create file system with specified number of disk sectors.
- -Z
- Fill file with zeroes instead of creating a sparse file.
Anewfs_sysvbfs command first appeared in
  NetBSD 4.0.
The sysvbfs support is still experimental and there are few sanity checks.