Ok, I've figured out where the MPI library is located. Now I run the 
following command for compiling stuff in Ubuntu 17.04 by:
<terminal>
./configure --enable-build-doc 
-with-mpi-lib=/usr/lib/x86_64-linux-gnu/openmpi/lib
</terminal>
and the output correctly shows that MPI is supported now. The bootstrap 
MPI example also works fine.
Best,
Artur
Am 03.06.2017 um 17:32 schrieb Artur Tarassow:
 Dear all,
 
 just by chance, I've found the following gretl warning:
 
 <gretlcli>
 
 *** Warning ***
 *
 * gretl is built using OpenMP, but is linked against
 * OpenBLAS parallelized via pthreads. This combination
 * of threading mechanisms is not recommended. Ideally,
 * OpenBLAS should also use OpenMP.
 
 </gretlcli>
 
 I am not sure how to respond to this correctly.
 
 Usually I compile gretl on ubunty by running
 
 <terminal>
 ./configure --enable-build-doc --enable-openmpi
 </terminal)
 
 and get the output
 
 <configure>
 
    Installation path:                      /usr/local
    Use readline library:                   yes
    Use gnuplot for graphs:                 yes
    Use pdflatex for typesetting:           yes
    Use libgsf for zip/unzip:               no
    sse2 support for RNG:                   yes
    OpenMP support:                         yes
    MPI support:                            no
    AVX support for arithmetic:             yes
    Build with GTK version:                 2.0
    Build gretl documentation:              yes
    Use Lucida fonts:                       no
    Build message catalogs:                 yes
    Build gretl addons:                     no
    X-12-ARIMA support:                     yes
    TRAMO/SEATS support:                    yes
    libR support:                           yes
    ODBC support:                           no
    JSON parsing support:                   yes
    Experimental audio support:             no
    Use xdg-utils in installation:          if DESTDIR not set
 
    LAPACK libraries:
      -llapack -lblas -lgfortran
 
 </configure>
 
 The package libopenmpi-dev is installed.
 
 $sysinfo yields
 
 <sysinfo>
 
 bundle anonymous:
   nproc = 4
   blascore = Haswell
   hostname = atdesktop
   os = linux
   mpi = 0
   blas = openblas
   omp_num_threads = 4
   omp = 1
   blas_parallel = pthreads
   mpimax = 0
   wordlen = 64
 
 </sysinfo>
 
 
 Any thoughts? Thanks
 
 Artur