abinit/NEWS

Latest news
===========

User-visible changes
--------------------

### Main binaries of Abinit ###

When building Abinit 6, the greatest difference with respect to Abinit 5
is that only one flavour of the "abinit" main binary will be built at
once. The former "abinis" and "abinip" flavours have been replaced by
wrapper scripts which will work only after a "make install" has been
performed. These wrappers have been made available to facilitate the
transition and will be removed in version 6.1 or 6.2.

More precisely, this means that all occurences of "abinis" and "abinip"
in calculation scripts will have to be replaced by calls to "abinit", or
by symbolic links. If you wish however to continue using concurrently a
serial and a parallel version of Abinit, you'll have to build them
separately. In order to easily distinguish them at install-time, you may
use the "--with-program-suffix" option of the configure script.

This change was necessary to be able to run the whole test suite on any
flavour of Abinit (e.g. with MPI, ScaLAPACK, or FFTW support), and to
make the management of the Fortran modules possible. The main results
are an increased modularity of the source code, an improved robustness,
and an earlier detection of bugs and design flaws.



### Parallel builds ###

It is now possible to build Abinit in parallel - with "make -j<n>" -
using an arbitrary value of "<n>". Tests have been performed up to 16
processors, resulting in the very good speed-up factor of 15.1. This is
particularly important on architectures where the build is slow, e.g.
Itaniums with the Intel Fortran compiler.

Parallel builds will nevertheless work for the core source of Abinit
only. Convenience targets are thus provided to work around the
limitations of the plugins: "multi" and "mj4". It is possible to tune
the number of processors for "multi" by specifying e.g.:

  make multi multi_nprocs=16

on the command-line. For mj4, which is mainly used for automatic builds,
the number of processors is fixed to 4.



### Test suite ###

Several improvements have been done to the test suite, in order to
better support the various situations it can be used within. In
particular, "make check" now properly succeeds when all tests pass.



### Install ###

The install prefix of Abinit is now fully left to the user's choice. The
build system will not try anymore to add further prefixes, such as
version numbers. This change greatly improves the flexibility of the
install procedure and was long-awaited by packagers.



### MPI ###

MPI support in Abinit has been thoroughly cleaned-up, plus made more
robust and more consistent. The build system is also much stricter about
the way options can be specified.

At configure-time, the build system now behaves the following way:

  * if no option is given, the build system will take the decision
    whether to enable MPI depending on the build environment; the
    parallel code will be built if MPI-capable C and Fortran compilers
    are found, as well as a working MPI runner;

  * if --enable-mpi is specified, the build system will activate the
    build of the parallel code, regardless of what has been detected;
    it is supposed that the users know what they are doing (ahem!);

  * if --with-mpi-prefix is used, the build system will set the build
    parameters according to what if finds in the specified directory;
    in this case, manually setting the compilers or the MPI runner is
    strictly forbidden.



### XLF ###

XLF is not wrapped anymore by the build system, which allows for a
finer-grained control of the build but may also cause some new problems.

Please consult ~abinit/README.xlf for troubleshooting, and do not
hesitate to enhance this file with your successful tricks by sending
them to Yann Pouillon <yann.pouillon@ehu.es>.



### Config files ###

The build system is now much less tolerant about obsolete options to the
configure script. Outdated config files will thus likely cause errors.

Build examples (found in ~abinit/doc/build/config-examples), as well as
their template (~abinit/doc/build/config-template.ac9), have been
substantially modified, to match the changes in the build system. All
personal config files (usually found in ~/.abinit/build/) should be
updated using this material as reference.



Developer-visible changes
-------------------------

### Fortran modules ###

All ".mod" files generated during the build of Abinit are now stored in
a separate directory, src/mods/. This strategy addresses several tricky
issues for the build system. In particular:

  * it is now much simpler to access them, since there is only one
    directory to include;

  * it is much easier to clean them all, and check that they have
    actually been removed.

This option has however not been activated for the plugins, since their
respective build systems do not support this kind of trick.



### Hand-written include files ###

Hand-written include files, i.e. C headers at present, should be stored
in src/incs/ to be properly recognized by the build system.

The "DBG_ASSERT" and "ABI_ASSERT" macros of abi_common.h have been
deactivated because they were not portable enough. They should be fixed
and improved.



### Installable libraries ###

The support for installable libraries, aka "exports", is still under
heavy development. Such libraries are built in src/libs/ when the
"--enable-exports" option of configure is used.

For the moment, this feature is used to export Python bindings to the
Abinit parser, for use in other codes usch as V_Sim. Only GCC is
currently supported, and the full activation of this feature will
require the implementation of Libtool support into the build system.

Please contact Yann Pouillon <yann.pouillon@ehu.es> if you are
interested by this feature.



### Compile flags ###

The management of compile flags has undergone several improvements. They
include:

  * the complete separation of optimization and debug flags;

  * the enhancement of debug flags (many more warnings);

  * the creation of a specific flag category for tricks;

  * the ability to specify additional flags via environment variables,
    i.e. "*FLAGS_EXTRA".

The extra flags provide a significant additional flexibility, since they
do not short-circuit the build system auto-detection process, contrary
to the use of bare flags. For instance:

  FCFLAGS_EXTRA="-dummy_option"

will be _appended_ to the compile flags set by the build system, while:

  FCFLAGS="-dummy_option"

will _replace_ them.

This way of doing is also meant to minimize the interferences between
the various steps of the configuration.



### Python ###

The proper detection of the Python environment is still under
development but has improved substanitially. More efforts will be
devoted to this part in the near future, and feature requests are now
welcome. Please send them to Yann Pouillon <yann.pouillon@ehu.es>.



### MPI ###

MPI preprocessing options are not handled anymore through external
CPPFLAGS, but via the "config.h" include file. As a consequence, they
have been renamed from "MPI_*" to "HAVE_MPI_*". This is to keep in mind
when developing new parallel code.

The confusing "--enable-mpi-io-buggy" option of configure has been
replaced by "--enable-mpi-io-test", for developers who want to check and
tune new MPI I/O related developments. It defines the HAVE_MPI_IO_TEST
macro, which should encapsulate such experimental code.



Maintainer-visible changes
--------------------------

### M4 macros ###

M4 macros have been refactored and strict naming conventions have been
adopted. See ~abinit/config/m4/ for details.



### Makefiles ###

The "defsinterfaces" target in config/makefiles/top.am has now
disappeared. It was previously required by the simultaneous build of the
serial and parallel libraries and has become completely useless.



### Information for packagers ###

The ~abinit/PACKAGING file contains essential information for packagers.
All maintainers of Abinit should feel free to improve and enhance this
file.



### File naming conventions ###

Legacies remaining from the prior use of TLA (an ancestor of the Bazaar
version control system) have all been removed. All incriminated files
have been renamed from ",,*" to "tmp-*". This is particularly visible in
the test suite.

This change was necessary because the Autotools use commas as separators
for sed substitutions, which was resulting in spurious crashes of the
configure script under some circumstances.



### Test suite ###

The timeout utility used for nightly builds has been moved from
src/nightly/ to tests/Nightly/.

The fldiff has been hacked to ignore extra output when MPI support is
activated. The absence of ripple effects should be checked carefully.



### MPI ###

Several binaries have had MPI support added, so that they can be tested
when the parallel code is built: anaddb, cut3d, lwf, mrgddb, mrgscr.
Though this should not affect developers, these changes should
only be considered temporary and a better solution provided.



### Checker scripts ###

The preprocessing option checker has been rewritten in Python and
re-targetted at finding forbidden options. It may be updated and
enhanced at will (see util/source/check-cpp-options.py).

This script should be used on a more systematic basis, together with the
conflict marker checker (util/source/check-conflict-markers.py).



Other news
----------

More news can be found in the [release-notes directory](https://docs.abinit.org/about/release-notes),
more specifically in the latest of the release_notes_v*.*. files.