Your Electronics Open Source

Overview
When the RFS content and storage media are ready; the developer can setup and mount RFS. First of all, we must select the file system for RFS, then convert the content to the required file system, or install the RFS on the devices.

File Systems
It is a comprehensive procedure to select the file systems, which is a balance of media properties, performance, system configuration. The developer should consider following issues when he design the file system. Of course, the developer can use two file systems as combination for embedded system.

• Is the file system writeable?
• Is the file system using pemernent storage?
• Should the system recovery from power off?
• Does the file system support compressed?
• Does the file loaded to RAM first?

Besides those, the developer has better to read the manual of selected file systems to find out its limitation.

NFS/RFS
It is important or very helpful to use NFS (Network File System) in embedded system in the development period. In that case, when the file system image is loaded in host side directory, the embedded system will consider it as its own part of RFS and run it. If the file system need to be updated, just reload the directory in the host side, rather than reprogramming the flash memory in embedded system.

CRAMFS. The compressed ROM file system (or cramfs) is a free (GPL'ed) read-only Linux file system designed by Linux Torvalds for simplicity and space-efficiency. It is working on RAM, but working as ROM (read only).

JFFS2 is a replacement for JFFS, developed by Axis Communications. It is the major file system used in embedded system. It supports many high-end file system features.

NFTL
If a block device is emulated on flash memory, then conventional FS such as ext2, ext3, XFS, JFS or reiserfs can be setup on NFTL.

RAM Disk
supports any kinds of file systems. The kernel can be configured to support initrd (initial RAM disk). Actually initrd is the simplest file system for RFS. After power off, the content in RAM disk is lost, so normally the content will be loaded from flash memory to RAM disk.

TMPFS is a file system based upon virtual memory. Its size is scalable according to actual content.