In message <20051027202331.GD12021@snowdrop.l8s.co.uk>, David Laight writes:
>On Thu, Oct 27, 2005 at 09:32:02PM +0200, Julio M. Merino Vidal wrote:
>> 
>> They are bigger than on-disk nodes, but not so much.  You can ceratinly keep
>> a bunch of them in memory, specially considering that a devfs doesn't have
>> a lot of nodes; you'll only have those that you really need.
>
>One thing that /dev does have is a lot of inodes.  What it doesn't have
>is files, so no need for block allocation maps.
>
>I also wonder whether it should be possible to pass names like
>/dev/pts/<number> directly to the driver without there being an existing
>declared device.

I fear that that would break things.  Have a look at oldttyname()
in /usr/src/lib/libc/gen/ttyname.c -- is there other code like that 
anywhere?  (I also see the special case earlier in ttyname.c for ptys.)

More generally -- it doesn't matter if there is an i-node or nor in 
some data structure, or if there's an actual directory /dev/pts.  What 
matters is whether or not it acts as if there's one.

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb