Experiences with CHFS/ChewieFS

[nia <nia%NetBSD.org@localhost>]

CHFS/ChewieFS was one of the things I learned existed early as a NetBSD
user, but it occurs to me I've never seen any hardware that has the
sort of raw flash device it requires.

Until very recently when someone noticed while testing with some
virtual flash storage with rump, `mount -t` didn't work with CHFS.

I asked on IRC if anyone had used it with non-virtual flash storage,
and someone commented that they'd used it once, but didn't find it
useful. This was because it reads and buffers all metadata in RAM,
which is slow and unsuitable for the sort of low memory embedded
boards which apparently have raw flash - although I suspect all the
new ones have eMMC instead.

The man page still lists:

"CHFS has a few known bugs as of 2011.  Writing the FS full can cause
problems.  Truncating a file and growing it again can cause the new bytes
not having all zeroes, but filled with the old content instead."

Have you used CHFS, and what was your experience with it?