That's no problem at all.

Good. This version explicitly check for instantiation as global, and also does some further sanity checks prior to startup.

ftp://ftp.openldap.org/incoming/pierangelo-masarati-2010-04-20-rdnval.2.c

It now just fails in the same was as without the patch. I'll mention it on openldap-technical if I can't get assistance on #ldap.

Not quite clear what patch and what failure you refer to. Anyway, I've tested this version of the overlay as global (refuses to start) and on a database, either empty or populated, and it works as intended. Please test and report. Thanks, p.