Open project proposal 2010: Pramfs


Marco Stornelli <marco.stornelli@...>
 

Proposer: Marco Stornelli

Summary: Add Pramfs filesystem to the kernel mainline

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.

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