source: lmdz_wrf/WRFV3/arch/README.canonical_stanza @ 1

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#ARCH    <os> (fortran) compiler with (C) compiler # serial smpar dmpar dm+sm
#
# (The last four words on the line above indicate what parallel modes are supported for this build.
#  Presence of serial indicates the code can be built single-threaded and an option will be presented
#  by the configure script for this.  Likewise, presence of smpar indicates shared-memory parallel (OpenMP),
#  dmpar indicates distributed memory parallel (MPI), and dm+sm indicates both.  The comment character
#  before the first word is not necessary but it makes the choices neater when the configure script 
#  displays them to the user)
#
# (The settings below should be all that are needed per architecture/installation. The rest of the 
#  configuration settings are based on these and are done in the postamble (arch/postamble) )
#
DMPARALLEL      =       # 1
OMPCPP          =       # -D_OPENMP
OMP             =       # (compiler dependent option for openmp, e.g. -mp for pgi; leave commented out)
SFC             =       (serial fortran compiler)
SCC             =       (serial C compiler)
DM_FC           =       (Fortran compile command for mpi, eg: mpif90 -f90=$(SFC))
DM_CC           =       (C compile comand for mpi, eg: mpicc -cc=$(SCC))
FC              =       CONFIGURE_FC    (leave as is: to be filled in by configure depending on parallel option)
CC              =       CONFIGURE_CC    (leave as is: to be filled in by configure depending on parallel option
LD              =       $(FC)           (usually leave as is)
RWORDSIZE       =       CONFIGURE_RWORDSIZE   # filled in by configure or hard coded to 8 (for var)
PROMOTION       =       (compiler specific option for promotion: e.g. -r$(RWORDSIZE) -i4)
ARCH_LOCAL      =       (local additions to ARCHFLAGS)
CFLAGS_LOCAL    =       (local additions to CFLAGS)
LDFLAGS_LOCAL   =       (local additions to LDFLAGS)
FCOPTIM         =       (optimization options to Fortran compiler)
FCREDUCEOPT     =       (optional: used by noop_exceptsions for certain routines that won't work with full opt on certain compilers)
FCNOOPT         =       (flag that turns off optimization)
FCDEBUG         =       (debug and no optimization options to Fortran compiler)
FORMAT_FIXED    =       (fortran compiler option for fixed format)
FORMAT_FREE     =       (fortran compiler option for free format)
FCSUFFIX        =       (tell the compiler what a fortran file's suffix looks like -- AIX needs)
BYTESWAPIO      =       (option to give bigendian unformatted fortran output, if needed)
FCBASEOPTS      =       $(FCDEBUG) $(FORMAT_FREE) $(BYTESWAPIO) (basic options to fortran compiler, but not optim.)
MODULE_SRCH_FLAG =      (flag to compiler to tell it where to search for modules -- PGI needs)
TRADFLAG        =       (flag to cpp to tell it to act like it did before script kiddies got hold of it)
CPP             =       (cpp command)
AR              =       (ar command)
ARFLAGS         =       (flags to ar command, want ru capability)
M4              =       (m4 command)
RANLIB          =       (ranlib command if needed)
CC_TOOLS        =       (the cc command that should be used for compiling in the tools directory. Often just cc or $(SCC) )

#optional (used for BG/L, for example, where the mpi args and paths have to be specified explicitly)
MPI_INC         =       (e.g. -I/bgl/BlueLight/ppcfloor/bglsys/include)
MPI_LIB         =       (e.g. -L/bgl/BlueLight/ppcfloor/bglsys/lib -lmpich.rts -lmsglayer.rts -lrts.rts -ldevices.rts)

---
Here is an example:

###########################################################
#ARCH    Linux x86_64, PGI compiler with gcc # serial smpar dmpar dm+sm
#
DMPARALLEL      =       # 1
OMPCPP          =       # -D_OPENMP
OMP             =       # -mp -Minfo=mp
SFC             =       pgf90
SCC             =       gcc
DM_FC           =       mpif90 -f90=$(SFC)
DM_CC           =       mpicc -cc=$(SCC)
FC              =       CONFIGURE_FC
CC              =       CONFIGURE_CC
LD              =       $(FC)
RWORDSIZE       =       CONFIGURE_RWORDSIZE
PROMOTION       =       -r$(RWORDSIZE) -i4
ARCH_LOCAL      =       -DNONSTANDARD_SYSTEM_SUBR # but for ifort compiler, it is -DNONSTANDARD_SYSTEM_FUNC
CFLAGS_LOCAL    =       -w -O3
LDFLAGS_LOCAL   =      
FCOPTIM         =       -fastsse -Mvect=noaltcode -Msmartalloc -Mprefetch=distance:8 -Mfprelaxed # -Minfo=all =Mneginfo=all
FCREDUCEDOPT    =       $(FCOPTIM)
FCNOOPT         =       -O0
FCDEBUG         =       # -g $(FCNOOPT)
FORMAT_FIXED    =       -Mfixed
FORMAT_FREE     =       -Mfree
FCSUFFIX        =
BYTESWAPIO      =       -byteswapio
FCBASEOPTS      =       -w $(FCDEBUG) $(FORMAT_FREE) $(BYTESWAPIO)
MODULE_SRCH_FLAG =     -module $(WRF_SRC_ROOT_DIR)/main
TRADFLAG        =      -traditional
CPP             =      /lib/cpp -C -P
AR              =      ar
ARFLAGS         =      ru
M4              =      m4 -B 14000
RANLIB          =      ranlib
CC_TOOLS        =      $(SCC)