Frank,
Try using
http://os.inf.tu-dresden.de/~fm3/emul_l4rm.c
as replacement for l4rm in L4Linux applications
This file solved my problems ...BUT... I would just like to point out that the access rights provided via the flags-parameter is not used in the call to l4dm_map_pages(). I changed this by just passing the flags-parameter directly into l4dm_map_pages() - Now L4DM_RO works.
Cheers Leon