On Sat, 27 Sep 1997, William O Ferry wrote:

> [ -- Union mounting local changes over /usr/src, then adding NFS -- ]
>
>     Doing this union mount over NFS seems not to work.  The directories
> are union mounted to /usr/src on the sparc, and everything is fine.  Yet
> if I try to look at the sparc's /usr/src via NFS, it's empty.  If I NFS
> mount the directories that make up the union mount and try to union
> mount them together on the PC side, I get "mount_union: Operation not
> supported".
> 
>     Is there some way to get NetBSD to export local mounts, such as
> union mounts?  Or is there some way to get around mount_union's
> complaint??
> 
	From the BUGS section of 'mount_union'
	     "Without whiteout support from the filesystem backing the
	     upper layer, there is no way that delete and rename
	     operations on lower layer objects can be done.  An attempt
	     to mount a union directory under one which does not have
	     whiteout support will return EOPNOTSUPP (``Operation not
	     supported'')."
	NFS does not support whiteouts :(
	Providing you don't need to delete or rename anything in the
	union filesystem, it should be possible to make NetBSD allow
	union mounts from NFS filesystems, and simply fail on unlink()
	or rename() operations.

>     Any suggestions (including a better way to keep my changes separated
> from the NetBSD source) would be greatly appreciated.  Thanks in advance.
> 
	If you have the space for another copy of the source tree you
	could use sup, then import into your own personal tree using cvs.
	This would probably make merging easier.

	Then again you could just have the source tree on the PC, which
	would make compiling faster (local vs nfs filesystem :)

		David/abs