Debugging FS-UAE

This page contains some information on how you can better debug FS-UAE problems. In general, checking the contents of FS-UAE.log.txt is a good source of information, as is checking messages printed to stdout. You can make FS-UAE print log output to stdout with:

fs-uae --stdout

Environment variables

Some environment variables can be set to aid with debugging problems:


This will cause FS-UAE to log more information about input events to the log file.


This will cause FS-UAE to log all file system operations (for mounted directories) to the log file.





Compiling a debug version

If you experience a crash, it is helpful to have a stack trace for when the crash occurs. To compile a version suitable for debugging crashes, you might want to compile a version with debug symbols (-g) and with optimizations tuned for debugging (-Og):

cd fs-uae-(version)
make clean
make make CFLAGS="-g -Og" CXXFLAGS="-g -Og"

You can run FS-UAE from the source directory without installing it, just stay in the top of the project directory and run (using Linux as an example):

./fs-uae <optional args>

You can run FS-UAE through gdb like this:

gdb --args ./fs-uae <other args>

If the program crashes through gdb when input is grabbed, it can be a bit awkward (you may need to switch to a virtual console and kill fs-uae/gdb), so the following is highly recommended to avoid that from happening:

gdb --args ./fs-uae --no-initial-input-grab <other args>

or, perhaps better: to make FS-UAE never grab input automatically - neither on startup nor when clicking in the FS-UAE window:

gdb --args ./fs-uae --no-automatic-input-grab <other args>