Re: ramdisk/tmpfs/ramfs/memfs ?

From: Christoph Rohland (
Date: Fri Apr 27 2001 - 10:38:19 EST

Hi Padraig,

On Fri, 27 Apr 2001, Padraig Brady wrote:
> I don't have swap so don't need tmpfs, but could probably
> use it anyway without a backing store?

Yes, it does not need backing store.

> Anyway why was ramfs created if tmpfs existed, unless tmpfs requires
> backing store? They both seem to have been written around the same
> time?

- shm fs was written as a specialized fs to implement POSIX shared
  memory based on SYSV shm.
- ramfs was introduced shortly after shm fs and was meant as a
  programming example for a minimal virtual filesystem.
- Later shm fs was redone to use the same methods like ramfs but still
  was only useable for shared memory.
- After the release of 2.4.0, I extended shm fs to support read/write
  and thus be tmpfs and since then it can replace ramfs.


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