Do PTHREAD_PROCESS_SHARED mutexes/condvars work?

I need to do some process syncronization, but the PTHREAD_PROCESS_SHARED
attribute does not seem to work. I am using NGPT 2.0.4, and I have tried a
stock 2.4.19 with the futex patch, and a 2.5.43 development kernel.  Both
kernel versions have the same results.  I have some test code that yields
the error, and I have made one modification to test_str03.c that also shows
the error.  

The error comes from pthread_mutex_lock() when the mutex is locked by
another process (the mutex data is shared via shared memory, and initialized
with an attribute that has PTHREAD_PROCESS_SHARED set).  The error is
EDEADLK.

I can post the test code I have and the change to get test_str03 to fail, if
there is interest in helping out.  But I wanted to make sure that NGPT tries
to support PTHREAD_PROCESS_SHARED before I posted all of that.  The
documentation seems to say that NGPT does and does not support
PTHREAD_PROCESS_SHARED in different places(there is a test for the case,
test_str03, but you have to supply a -s parameter, and then that really
doesn't work anyway...).

Thanks,
Chris McFarlen
T-NETIX, Inc.