KIP and other user mappings

Hi,

In L4, what offsets and pages does the userspace need to know about by standard?

On ARM (NICTA::Pistachio hello 1.1) for instance, KernelInterface() is
entered via a trap at offset 0xFFFFFFb4, and there are other traps
nearby. Does the userspace need to know about these by standard or are
they there for convenience? My expectation would be that it would only
need to know a fixed offset for KernelInterface() call.

Also, are there other pages than the KIP that the userland expects to
find? For instance, USER_UTCB_REF is defined at 0xFF000FF0
(l4/include/arm/vregs.h), almost at the end of the KIP page for ARM.
Is it part of the KIP? Does the userspace need to know it's offset in
advance, or is it to be discovered from the KIP?

Thanks,
Bahadir