GSoC RTEMS compilation issues

[WL]

To select some features to be included during compilation I added:

RTEMS_CPUOPT([__RTEMS_ENABLE_HYPERVISOR__],
  [test x"${ENABLE_HYPERVISOR}" = x"1"],
  [1],
  [switch into hypervisor compilation mode])

to rtems/cpukit/configure.ac together with

#if defined (__RTEMS_ENABLE_HYPERVISOR__)
...
#endif

clauses inside a couple *.c and *.h files. Now while invoking the
./configure script, I'm adding ENABLE_HYPERVISOR=1 as a parameter. The
problem is that in certain header files the
__RTEMS_ENABLE_HYPERVISOR__ is not recognized and compilation proceeds
as the parameter hadn''t been passed. Furthermore, it seems as if for
a given header file the parameter is recognized while being included
from some files and from some others it is not. Did this happen with
other cases with conditional compilation? If yes, what was the
solution? I've been looking into this but at the moment I've got
nothing.