This README contains instructions on how to download and build MPICH CH4 over OFI Libfabric on Blue Gene /Q.  Please note that the V1R2M4 driver is required.  There are three github repositories with the relevant code.  The first of these is this github which is the build environment itself.
mkdir <build_env_root_dir>
cd  <build_env_root_dir>
git clone https://github.com/pkcoff/OFI-BGQ-BuildEnv.git

Then clone the libfabric github repo into this environment:
cd OFI-BGQ-BuildEnv/ofi
git clone https://github.com/ofiwg/libfabric.git

Then clone the mpich github repo into this environment:
cd ../mpi
git clone https://github.com/pmodels/mpich.git

Then create a link from the mpich directory into libfabric to support the libfabric embedded build within mpich:
cd mpich/src/mpid/ch4/netmod/ofi &&   ln -s `cd ../../../../../../../ofi/libfabric && pwd` 

Then run autoconf as follows:
cd <build_env_root_dir>/OFI-BGQ-BuildEnv
./autogen.sh --with-autotools=/soft/buildtools/autotools/feb2015/bin   ---> add the --with-autotools in the Argonne machines due to downlevel autoconf default
./configure
cd ofi/libfabric
./autogen.sh --with-autotools=/soft/buildtools/autotools/feb2015/bin
cd ../../mpi/mpich
./autogen.sh --with-autotools=/soft/buildtools/autotools/feb2015/bin
cd ..
vi simple_configure
  --- change : ${INSTALL_DIR:= to the install dir you want

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SPECIAL NOTE FOR BUILDING ON MIRA:
Mira is currently still at V1R2M2 and has not yet moved to V1R2M4.  As a workaround for now,
the V1R2M4 system files have been made available in /soft/libraries/unsupported/V1R2M4-sys.
To utilize them, you'll need to change the following 2 files:

config.site: change this:

MPICHLIB_CPPFLAGS="-I/bgsys/drivers/ppcfloor/spi/include/kernel/cnk -I/bgsys/drivers/ppcfloor"

to this:

MPICHLIB_CPPFLAGS="-I/soft/libraries/unsupported/V1R2M4-sys/spi/include/kernel/cnk -I/soft/libraries/unsupported/V1R2M4-sys"

ofi/libfabric/prov/bgq/configure.m4: change this:

bgq_driver=/bgsys/drivers/ppcfloor

to this:

bgq_driver=/soft/libraries/unsupported/V1R2M4-sys
  
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then for gnu 4.7.2 build:
cd <build_directory>
DEBUG build:
CONFIG_TOOLCHAIN=gnu  CONFIG_FLAVOR=debug <build_env_root_dir>/ofi-bgq/mpi/simple_configure
OPT build:
CONFIG_TOOLCHAIN=gnu  CONFIG_FLAVOR=optimized <build_env_root_dir>/ofi-bgq/mpi/simple_configure

then:
make -j16 install

Look in <build_env_root_dir>/config.site for details on compilers and options.