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README_FOR_DEVELOPERS.md

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Structure of the toolchain scripts:

  • install_cp2k_toolchain.sh is the main script that will call all other scripts. It contains default flag settings, user input parser, calls to each package installation scripts and the generator of the CP2K arch files.

  • script/install_*.sh are the installation scripts for individual packages. They are relatively independent, in the sense that by running script/install_PKG.sh it should install the package on its own. However, in practice due to dependencies to other libraries, sometimes for a package to be installed this way, it will depend on other libraries being already installed and the correct environment variables set. At the end of each script, it should write to two files: build/setup_PKG and install/setup.

    • The build/setup_PKG file contains all the instructions to set the variables used by the install_cp2k_toolchain.sh and other script/install_PKG.sh scripts in order for them to correctly compile the toolchain and set the correct library flags for the arch files.
    • The install/setup file contains all the instructions for setting up the correct environment before the user can compile and/or run CP2K.

  • script/toolkit.sh contains all the macros that may be used by all of the scripts, and provides functionalities such as prepending a path, checking if a library exists etc.

  • script/common_var.sh contains all of the common variables used by each installation scripts. All of the variables in the file should have a default value, but allow the environment to set the values, using: VAR=${VAR:-default_value}.

  • script/parse_if.py is a python code for parsing the IF_XYZ(A|B) constructs in the script. Nested structures will be parsed correctly. See IF_XYZ constructs below.

  • checksums.sha256 contains the pre-calculated SHA256 checksums for the tar balls of all of the packages. This is used by the download_pkg macro in script/toolkit.sh.

  • arch_base.tmpl contains the template skeleton structure for the arch files. The install_cp2k_toolchain script will set all the variables used in the template file, and then do an eval to expand all of ${VARIABLE} items in arch_base.tmpl to give the cp2k arch files.

enable-FEATURE options

The enable-FEATURE options control whether a FEATURE is enabled or disabled. Possible values are:

  • yes (equivalent to using the option-keyword alone)
  • no

with_PKG and PKG_MODE variables:

The with_PKG options controls how a package is going to be installed:

  • either compiled and installed from source downloaded (install, or the option-keyword alone),
  • or linked to locations provided by system search paths (system),
  • or linked to locations provided by the user (<path>, path to some directory),
  • or that the installer won't be used (no).

For most packages the with_pkg variables will act like a switch for turning on or off the support for this package. However, for packages serving the same purpose, with the installer needing only one, an extra variable PKG_MODE (e.g. MPI_MODE) are used as a selector. In this case, while with_PKG controls the installation method, the PKG_MODE variable picks which package to actually use. This provides more flexibility.

The IF_XYZ constructs

Due to the fact that install_cp2k_toolchain.sh needs to produce several different versions of the arch files: popt, psmp, pdbg, sopt, ssmp etc, it will have to resolve different flags for different arch file versions.

The solution used by this script is to use a syntax construct:

IF_XYZ(A | B)

A parser will then parse this expression to A if XYZ is passed to the parser (python parse_if.py filename XYZ); and to B if XYZ is not passed as command line option (python parse_if.py filename).

The IF_XYZ(A|B) construct can be nested, so things like:

IF_XYZ(IF_ABC(flag1|flag2) | flag3)

will parse to flag1 if both XYZ and ABC are present in the command line arguments of parser_if.py, to flag2 if only XYZ is present, and flag3 if nothing is present.

To ensure portability:

  • one should always pass compiler flags through the allowed_gcc_flags and allowed_gfortran_flags filters in scripts/toolkit.sh to omit any flags that are not supported by the gcc version used (or installed by this script).

  • note that allowed_gcc_flags and allowed_gfortran_flags do not work with IF_XYZ constructs. So if you have something like:

FCFLAGS="IF_XYZ(flag1 flag2 | flag3 flag4)"

Then you should break this into:

XYZ_TRUE_FLAGS="flags1 flags2"
XYZ_FALSE_FLAGS="flags3 flags4"
# do filtering
XYZ_TRUE_FLAGS="$(allowed_gcc_flags $XYZ_TRUE_FLAGS)"
XYZ_FALSE_FLAGS="$(allowed_gcc_flags $XYZ_FALSE_FLAGS)"

So that:

FCFLAGS="IF_XYZ($XYZ_TRUE_FLAGS | $XYZ_FALSE_FLAGS)"

  • For any intrinsic fortran modules that may be used, it is best to check with check_gfortran_module macro defined in script/tool_kit.sh. Depending on the gcc version, some intrinsic modules may not exist.

  • Try to avoid as much hard coding as possible: e.g. instead of setting:

./configure --prefix=some_dir CC=mpicc FC=mpif90

use the common variables:

./configure --prefix=some_dir CC=${MPICC} FC=${MPIFC}

To keep maintainability it is recommended that we follow the following practices:

  • Reuse as much functionality from the macros defined in the script/toolkit.sh as possible

  • When the existing macros in script/toolkit.sh do not provide the functionalities you want, it is better to write the new functionality as a macro in script/toolkit.sh, and then use the macro (repeatedly if required) in the actual installation script. This keeps the installation scripts uncluttered and more readable.

  • All packages should install into their own directories, and with a lock file created in their respective directory to indicate installation has been successful. This allows the script to skip over the compilation stages of already installed packages if the user terminated the toolchain script at the middle of a run and then restarted the script.