Overview

• JFFS:Journaling flash filesystem. Allows read write access to flash.
• JFFS2:Journaling flash filesystem with compression. Allow read write access and has wear-levelling.
• ROMFS:Read only filesystem. Easy and simple.
• CRAMFS:Read only, compressed rom image.

The filesystems above can be combined with the virtual memory filesystem
to provide writeable storage.

When to use what

The most important question is: Do you need write access? If you do then JFFS2 is the logical choice. For read access ROMFS is the smallest, but if you need compression to fit all your data take a look at CRAMFS.

Initrd

Another option is to go with the initrd route. This allows only read only access of course but a few advantages. If you piggyback your fs on to your kernel the prom will load the entire image from flash, so the kernel doesn't need to know anything about the flash. It will be user-proof.