Models dependent on INET are crashing on Windows

inet-framework / inet

INET Framework for the OMNeT++ discrete event simulator

https://inet.omnetpp.org

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Models dependent on INET are crashing on Windows #257

Closed rhornig closed 7 years ago

rhornig commented 7 years ago

Models that are using INET as a linked shared library (DLL) on Windows reported various unexplained crashes. For example in SimuLTE it was surfacing as an error stating that configuration of the network has failed. This is Windows specific and does not occurred if INET was compiled as a static library.

rhornig commented 7 years ago

A bit investigation shows that this happens because:

On Windows OMNeT++ is configured to use 'AUTO IMPORTING' for all shared libs DLL. This means that ALL symbols contained in the DLL are exported by the linker automatically.
The number of symbols in INET exported this was is around 74.000
Sadly Windows does not support more 65536 symbols in the export table
Even more sadly, the mingw linker does not throw an error that the number of symbols were exceeded. It just generates a code silently where the symbol table is over indexed and garbage addresses are assigned to symbols leading to runtime crashes. This seems to be fixed in March 2017 in the linker, so future versions will hopefully report an error.

rhornig commented 7 years ago

Solution for the problem.

OMNeT++ must be modified NOT to use -Wl,--enable-auto-import on Windows. It's the default setting anyway if someone does not specify the exported symbols manually.
To have backward compatibility INET's makefrag file should be modified to remove the above flag explicitly from LDFLAGS.
INET_EXPORT should be added as a define when compiling INET on windows to activate the INET_API macro and export all marked classes manually.
-P INET should be added to the makemake file and in the Project Settings so proper INET_API macros are generated for the message files.
With manual exporting the number of symbols fall to around 20300 which is well under the 65536 limit.

rhornig commented 7 years ago

Added the needed changes to the project file, Makefile and makefrag

rhornig commented 5 years ago

Just for clarity. -Wl,--enable-auto-import has nothing to do with this. The problem is that too many symbols are exported. By default all symbols are exported unless we activate the INET_API macro (which was empty until now. It was active only for visual c compiler). I.e. on clang/gcc the macro was not defined so all symbols were exported. The solution was to activate the export macro and reduce the export table size.