On Tue, 11 Dec 2007, Bill Stouder-Studenmund wrote:
> Note that -o union != mount -t unionfs. Also, my understanding was
> that unionfs created the whiteouts, so that even if tmpfs supported
> them, you wouldn't see a difference in how /dev is handled.

I know about the difference between mount -o union and mount -t unionfs,
but I thought that both were supposed to support whiteouts.  I see now
that in fact "mount_mfs -o union" and "mount_tmpfs -o unoin" both have
the same behaviour here: deleting a file that exists in the lower layer
really deletes it, it doesn't make a whiteout in the upper layer.

If there are no further issues with using tmpfs for "MAKEDEV -M", I
plan to commit my patch on Friday.

--apb (Alan Barrett)