The genromfs software project enables the creation of ROMFS images.
Romfs has been included in stock Linux kernels since version 2.1.21 (around January 1997) and is supported by all current kernel sources (2.4-2.6). However, depending on the distributor, it may not have been compiled into the Linux kernel.
A functioning Linux system requires both the kernel and some running programs, which, of course, also require a filesystem. Most Linux disk filesystems are designed to support POSIX features and have elaborate recovery methods on crashes (journaling), making them very heavy-weight and often impractical for special purposes.
Romfs shortcuts its way around this problem in two ways. Firstly, it is read-only, meaning that it is not possible to use a disk if it is romfs, as its image must be built in advance. Secondly, it stores only the bare minimum required from a filing system - no modification dates or Unix permissions.
In the latest version of Genromfs, there have been several fixes and improvements. These include compilation fixes for Cygwin and less dependence on the ntohl() implementation, and the inclusion of "-" "_", and "+" characters in acceptable names for "fake" device names. Overall, Genromfs is an efficient and useful tool for creating romfs images, making it a great option for those looking for a small, read-only filesystem.
Version 0.5.2: N/A