- when windows portable executables (.exe or .dll) files are loaded,
their dependent libraries not fully loaded. For OpenFOAM this means
that the static constructors which are responsible for populating
run-time selection tables are not triggered, and most of the run-time
selectable models will simply not be available.
Possible Solution
=================
Avoid this problem by defining an additional library symbol such as
the following:
extern "C" void libName_Load() {}
in the respective library, and tag this symbol as 'unresolved' for
the linker so that it will attempt to resolve it at run-time by
loading the known libraries until it finds it. The link line would
resemble the following:
-L/some/path -llibName -ulibName_Load
Pros:
- Allows precise control of forced library loading
Cons:
- Moderately verbose adjustment of some source files (even with macro
wrapping for the declaration).
- Adjustment of numerous Make/options files and somewhat ad hoc
in nature.
- Requires additional care when implementing future libraries and/or
applications.
- This is the solution taken by the symscape patches (Richard Smith)
Possible Solution
=================
Avoid this problem by simply force loading all linked libraries.
This is done by "scraping" the information out of the respective
Make/options file (after pre-processing) and using that to define
the library list that will be passed to Foam::dlOpen() at run-time.
Pros:
- One-time (very) minimal adjustment of the sources and wmake toolchain
- Automatically applies to future applications
Cons:
- Possibly larger memory footprint of application (since all dependent
libraries are loaded).
- Possible impact on startup time (while loading libraries)
- More sensitive to build failures. Since the options files are
read and modified based on the existence of the dependent
libraries as a preprocessor step, if the libraries are initially
unavailable for the first attempt at building the application,
the dependencies will be inaccurate for later (successful) builds.
- This is solution taken by the bluecape patches (Bruno Santos)
Adopted Solution
================
The approach taken by Bruno was adopted in a modified form since
this appears to be the most easily maintained.
Additional Notes
================
It is always possible to solve this problem by defining a corresponding
'libs (...)' entry in the case system/controlDict, which forces a dlOpen
of the listed libraries. This is obviously less than ideal for large-scale
changes, but can work to resolve an individual problem.
The peldd utility (https://github.com/gsauthof/pe-util), which is
also packaged as part of MXE could provide yet another alternative.
Like ldd it can be used to determine the library dependencies of
binaries or libraries. This information could be used to define an
additional load layer for Windows.
- fix typo in makefiles/info that affected wmake -show-compile-c
- additional safeguard in src/OpenFOAM/Make/options against self-linking.
This is not normally required unless PROJECT_LIBS has been added into
the link stage.
- with the wmake rules we may have some compiler options bound to the
internal compiler variable. For example,
CC = g++ -std=c++11 -m64
c++FLAGS = ...
So shift any flags from CC to CXXFLAGS for the output of
'wmake -show-cxx', 'wmake -show-cxxflags', etc.
This makes it much easier to handle the values correctly elsewhere.
Eg,
CXX="$(wmake -show-cxx)" CXXFLAGS="$(wmake -show-cxxflags)" \
./configure
- can be useful for retrieving the compilation flags for use with other
make systems (eg, cmake)
* wmake -show-compile (C++ not C)
* wmake -show-cxx
* wmake -show-cxxflags
which may be optionally overridden by version-specific rules.
For example the default rules for gcc on GNU/Linux x86_64 are in the
wmake/rules/linux64Gcc directory. If there is a need to change any of
the rules for a specific version of gcc, e.g. gcc-4.8.4 the directory
wmake/rules/linux64Gcc48 may be created into which any of the language
files may be provided containing the rules to override the defaults.
The Makefiles are now in the makefiles sub-directory
The "-f | -force" option in wmakeLnInclude is now "-u | -update" for
consistency with the other scripts.
The "Usage" entry in the headers is now consistently formatted in all
scripts.
