Hi All, I'm not sure if this is supposed to work, but configuring with --with-thread-package=none results in compile-time warnings like: In file included from ./src/include/mpiimpl.h:3437, from src/mpi/rma/win_lock.c:8: ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_enter_lockname_impl_': ./src/include/mpiimplthreadpost.h:32: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_exit_lockname_impl_': ./src/include/mpiimplthreadpost.h:51: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_yield_lockname_impl_': ./src/include/mpiimplthreadpost.h:70: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_enter_lockname_recursive_impl_': ./src/include/mpiimplthreadpost.h:96: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_try_lockname_recursive_impl_': ./src/include/mpiimplthreadpost.h:125: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_exit_lockname_recursive_impl_': ./src/include/mpiimplthreadpost.h:159: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type ./src/include/mpiimplthreadpost.h: In function 'MPIU_Thread_CS_yield_lockname_recursive_impl_': ./src/include/mpiimplthreadpost.h:185: warning: passing argument 2 of 'MPIU_Thread_tls_get' from incompatible pointer type And fails to link cpi: CCLD cpi ld: warning: directory './src/mpl' following -L not found ld: warning: directory './src/openpa/src' following -L not found Undefined symbols: "_MPIU_Thread_cond_create", referenced from: _MPIR_Init_async_thread in libmpich.a(async.o) _MPIDI_CH3I_Progress_init in libmpich.a(ch3_progress.o) "_MPIU_Thread_tls_get", referenced from: _MPIU_Thread_CS_enter_lockname_recursive_impl_ in libpmpich.a(lib_libpmpich_la-comm_rank.o) ... "_MPIU_Thread_mutex_unlock", referenced from: "_MPIU_Thread_cond_broadcast", referenced from: _MPIDI_CH3I_Progress in libmpich.a(ch3_progress.o) "_MPIU_Thread_tls_create", referenced from: _dbg_init_tls in libmpich.a(dbg_printf.o) _MPIR_Init_thread in libmpich.a(initthread.o) "_MPIU_Thread_mutex_create", referenced from: _MPIR_Init_async_thread in libmpich.a(async.o) ... ... ld: symbol(s) not found collect2: ld returned 1 exit status make[2]: *** [cpi] Error 1 If this is not supposed to work, it might be better to fail during configure rather than letting things fail during compilation. ~Jim.