Add Pramfs filesystem to the kernel mainline

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Add Pramfs filesystem to the kernel mainline
Marco Stornelli


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


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.