CRAMFS File System
Debian CRAMFS (Compressed ROM File system) is a root file system that is derived from the Debian distribution and is trimmed down to fit (compressed) in a partition in on-board flash as small as 15MB. This size can be reduced further by removing the demo programs and associated data that are included in this distribution.
The Eurotech Debian CRAMFS image uses x11 (XFree86) as its GUI and includes several demo programs that run under x11. Many common x11 shared libraries are included in the JFFS2 root, including those necessary to run GTK programs.
Unlike the Ramdisk and JFFS2 distributions, the CRAMFS is read-only with some exceptions which are loaded into CRAMFS temporary file systems. Since the CRAMFS distribution also includes a JFFS2 partition, it should be shut down cleanly before removing power from the board.
The advantage of the CRAMFS distribution is that, in the event that the JFFS2 file system does get corrupted or otherwise become unmountable, the rest of the system will still be intact because it is read-only. Only the shadowed files will be reverted to their previous/default contents.
For more information about how CRAMFS and other embedded Linux technologies can support your project, contact us.