I've recently installed NetBSD-1.5.1/i386 on a test system so I can compare
its stability to 1.4.  I used the ISO boot CD to perform a full
installation, and added just a few packages (emacs, tcsh, Gnu utilities) to
get things started.

The next thing I wanted to do was reconfigure and recompile the kernel.  So
I downloaded the system sources and installed them in /usr/src/sys, and I
wanted to make a union mount on top of that to keep the distribution files
clean.

Unfortunately I'm not able to do so.  When I try to do an inverted union
mount under my own account, I get the error "Operation not permitted" even
though I own the upper layer (union) directory.

I am able to create the union mount as root, but this doesn't help because
all upper layer directories created will be owned by root, thus I can't use
it under my own account.  What's even worse is that when I tried to unmount
the union, the system pretends it doesn't exist!

Here's a transcript of what happened (starting from my own account):

clyde: {1} mount_union -b /usr/src/sys/ /home/trevin/sys/
mount_union: /home/src/sys on /home/trevin/sys/: Operation not permitted
clyde: {2} su
Password:
clyde: {1} mount_union -b /usr/src/sys /home/trevin/sys/
clyde: {2} exit
clyde: {3} exit
clyde: {3} cd sys/arch/i386/conf/
clyde: {4} touch testfile
touch: testfile: Permission denied
clyde: {5} cd ~
clyde: {6} su
Password:
clyde: {1} umount /home/trevin/sys/
umount: /home/trevin/sys: not currently mounted
clyde: {2} mount
/dev/wd0a on / type ffs (local)
/dev/wd0f on /var type ffs (local)
/dev/wd0e on /tmp type ffs (local)
kernfs on /kern type kernfs (local)
/dev/wd1a on /home type ffs (local)
<below>:/home/src/sys on /home/trevin/sys/ type union
clyde: {3} umount -a -t union
umount: /home/trevin/sys: not currently mounted

Am I doing something wrong?  The mount command is fairly simple, and I used
it in my .login file under NetBSD-1.4.2 without any problem, but it's been
so long I don't remember whether I had to configure anything else first.

If not, I think I ought to report this problem to GNATS.

-----------------------
Trevin Beattie          "Do not meddle in the affairs of wizards,
trevin@xmission.com     for you are crunchy and good with ketchup."
      {:->                                     --unknown