> - what is the point of the fdesc file-system

The primary purpose is to provide /dev/fd/<file-descriptor>.  Our
fdesc filesystem is unusal that it also supplies /dev/{stdin,
stdout,stderr,tty}.  This pretty much requires that the union
filesystem be in the kernel and that fdesc be mounted over /dev.

> - when I don't mount fdesc, there is also /dev/tty, /dev/stdout, /dev/fd
>   and they happen to be different (char devices rather than pipes or whatnot).
>   what is the difference ?

We have at least one PR in the database that complains about problems
with the devices it replaces in /dev.  

Considering the problems with /dev/{stdin,stdout,stderr,tty} and the
fact that fdesc requires the union filesystem to be useful, I propose
that it be changed to only supply /dev/fd/<filed-descriptor> and be
mounted on /dev/fd.  At the moment, I can't think of any reason why
the present behavior is benefitial.

Comments and discussion re-directed to tech-kern.

	--jtc