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On an embedded system, we have a a 512Kb static ram on a character device /dev/mem.

We're currently using it by memory-mapping the file directly in our application with a mmap.

I would like to mount it as a file-system to enable the following use-cases:

  • manage stored data with system utilities
  • fast and reliable storage for important data (eg. rsyslog disk queue)
  • buffer data to be written on flash device

Would it make sense to mount it as a file-system?
How could I do it? Maybe using a loop device to make the file a block device?
What file-system should I consider?

  • Pardon me for being thick, but does the kernel maintain page descriptors for this ram? If so, then pramfs is possibly the solution to your problem, pramfs.sourceforge.net – MariusMatutiae Oct 17 '16 at 9:53
  • Sorry, I meant if not, but I wrote if so instead, exactly the opposite... – MariusMatutiae Oct 17 '16 at 12:20
  • Thank you @MariusMatutiae: pramfs seems exactly what I need. I wont be able to test it as I'm tied to an ancient sdk, but I'll consider it for future projects. Please post an answer and I'll mark it as accepted. – Matteo Nardi Oct 18 '16 at 9:20
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I would consider pramfs: the developers state:

Many embedded systems have a block of non-volatile RAM separate 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 or volatile data avoiding to write on a disk or flash. An example usage might be system logs under /var/log or debug information of a flight-recorder.

It has several advantages over traditional filesystems, is lightweight, and supports extended attributes, ACLs, security labels and freezing.

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