Comment 4 for bug 1594849

Tank you for pointing to the feature request and the discussion.

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From the man page (https://www.freedesktop.org/software/systemd/man/systemd-nspawn.html#--overlay=):

>For details about overlay file systems, see overlayfs.txt.

Which links to https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt, and there it is clearly defined, how overlayfs works.

So whatever nspawn does, it doesn't seem to conform to Linux kernel's notion of overlay file system.