Add Pramfs filesystem to the kernel mainline


 * Summary: Add Pramfs filesystem to the kernel mainline


 * Proposer: Marco Stornelli

Description
It would be nice to add Pramfs to the kernel mainline.

Many embedded systems have a block of non-volatile RAM seperate from normal system memory, i.e. of which the kernel maintains no memory page descriptors. For such systems it would be beneficial to mount a read/write filesystem over this "I/O memory", for storing frequently accessed data that must survive system reboots and power cycles. An example usage might be system logs under /var/log, or a user address book in a cell phone or PDA.

Currently Linux has no support for a persistent, non-volatile RAM-based filesystem, persistent meaning the filesystem survives a system reboot or power cycle intact. The existing RAM-based filesystems such as tmpfs and ramfs have no actual backing store but exist entirely in the page and buffer caches, hence the filesystem disappears after a system reboot or power cycle.

In the last review (end of June) some people have asked some modifications. The bigger ones are: fs layout endianess indipendent and a protection against system crash (a little journaling system for example). In the last version I closed all the open issues with the exception of the last one. It would be nice to close even this point to be ready for the mainline!


 * Related work : http://pramfs.sourceforge.net


 * Scope : This should take 6 weeks/man of development and test effort.

Comments
Tim Bird writes: Pramfs has been hanging around outside of mainline since CELF was created (2003), and was on our list of stuff to try to mainline then. It's been attempted at least 3 times, but maybe with your fixups to address feedback from LKML it can finally make it in.

I have my doubts as to how important the journaling feature is.