Compilation and Installation

Procedure

Use PuTTY to log in to the server as the root user.
Create a main program installation directory.
```
mkdir -p /path/to/MITGCM
```
Copy the installation package to the main program installation directory.
```
cp MITgcm_c67o.tar.gz /path/to/MITGCM
```
Go to the main program installation directory.
```
cd /path/to/MITGCM
```
Decompress the installation package.
```
tar -xvf MITgcm_c67o.tar.gz
```
Go to the directory generated after the decompression.
```
cd MITgcm
```

Configure the files.

Go to the build_options directory.
```
cd tools/build_options
```

Create and edit the Linux_arm64_gfortran file.

Create Linux_arm64_gfortran.
```
vi linux_arm64_gfortran
```

Press i to enter the insert mode and add the following content:

#!/bin/bash

MPI='true'
CC=mpicc
FC=mpif77
F90C=mpif90

DEFINES='-DWORDLENGTH=4 -DNML_TERMINATOR -DALLOW_USE_MPI -DALWAYS_USE_MPI'
EXTENDED_SRC_FLAG='-ffixed-line-length-132'
F90FIXEDFORMAT='-ffixed-form'
GET_FC_VERSION="--version"
OMPFLAG='-fopenmp'

NOOPTFLAGS='-O0 -g'
NOOPTFILES=''

CFLAGS='-O3 -march=armv8.2-a'
FFLAGS="$FFLAGS -fconvert=big-endian -fimplicit-none"
CFLAGS="$CFLAGS -fPIC"
FFLAGS="$FFLAGS -fPIC"
#-  with FC 19, need to use this without -fPIC (which cancels -mcmodel option):
# CFLAGS="$CFLAGS -mcmodel=medium"
# FFLAGS="$FFLAGS -mcmodel=medium"
#- might want to use '-fdefault-real-8' for fizhi pkg:
#FFLAGS="$FFLAGS -fdefault-real-8 -fdefault-double-8"

if test "x$IEEE" = x ; then     #- with optimisation:
   #- full optimisation
    FOPTIM='-O3 -funroll-loops -march=armv8.2-a'
    NOOPTFILES="$NOOPTFILES ini_masks_etc.F"
   #- can use -O2 (safe optimisation) to avoid Pb with some gcc version of -O3:
   #FOPTIM='-O2 -funroll-loops'
else
   # these may also be useful, but require specific gfortran versions:
   # -Wnonstd-intrinsics        for gfortran <= 4.3
   # -Wintrinsics-std           for gfortran >= 4.4
   # -Wno-tabs                  for gfortran >= 4.3
   # -Wno-unused-dummy-argument for gfortran >= 4.6
   #FFLAGS="$FFLAGS -Waliasing -Wampersand -Wsurprising -Wline-truncation"
   #- or simply:
    FFLAGS="$FFLAGS -Wall"
   #- to get plenty of warnings: -Wall -Wextra (older form: -Wall -W) or:
   #FFLAGS="$FFLAGS -Wconversion -Wimplicit-interface -Wunused-labels"
  if test "x$DEVEL" = x ; then  #- no optimisation + IEEE :
    FOPTIM='-O0'
  else                          #- development/check options:
    FOPTIM='-O0 -g -fbounds-check'
    FOPTIM="$FOPTIM -ffpe-trap=invalid,zero,overflow -finit-real=inf"
  fi
fi

F90FLAGS=$FFLAGS
F90OPTIM=$FOPTIM

# --------------------------
# NETCDF DIRECTORIES
# --------------------------
HDF5_HOME=/path/to/HDF5
NETCDF_HOME=/path/to/NETCDF

INCLUDEDIRS=''
INCLUDES="-I$NETCDF_HOME/include -I$HDF5_HOME/include"
LIBS="-L$NETCDF_HOME/lib -lnetcdff -lnetcdf -L$HDF5_HOME/lib -lhdf5_hl -lhdf5"

# -----------------------
# INCLUDE MPI DIRECTORIES
# -----------------------
MPI_HOME=/path/to/OPENMPI-4.0.1
MPI_INC_DIR=$MPI_HOME/include
INCLUDES="$INCLUDES -I$MPI_HOME/include"
INCLUDEDIRS="$INCLUDEDIRS $MPI_HOME/include"
MPIINCLUDEDIR="$MPI_INC_DIR"

Press Esc, type :wq!, and press Enter to save the file and exit.

Perform the compilation and installation, using exp4 as an example:
1. Go to the corresponding directory.
```
cd /path/to/MITGCM/MITgcm/verification/exp4/code
```
2. Rename SIZE.h_mpi to SIZE.h to replace the original SIZE.h file.
```
mv SIZE.h_mpi SIZE.h
```
3. Go to the corresponding directory.
```
cd /path/to/MITGCM/MITgcm/verification/exp4/build
```
4. Generate a makefile file.
```
../../../tools/genmake2 -mods=../code -mpi -of=../../../tools/build_options/linux_arm64_gfortran
```
5. Perform the compilation and installation.
```
make depend
make -j
```

Parent topic: MITgcm c67o Porting Guide (CentOS 7.6)