I sent my synth to a friend for testing and he is not able to even start it (Win and Linux).
On Linux (standalone application) he simply get the output
Illegal Instruction (core dumped)
On Windows (VST2 plugin) hosts will not see the plugin at all.
I did some research and found that at this is probably due to some optimization using CPU instructiions which might be not available on older CPU models. I looked into it and the release configs of my Linux release build are -O3, on Windows there seems to be no optimization (/Od).
Thinking about it, the Windows and Linux problems might be separate issues.
However at least the Linux build seems to be incorporating exotic CPU instructions.
Do I need to go lower than -O3?