When Firefly is launched on newest Intel or AMD CPUs under Linux, users can experience immediate program crash with SIGSEGV signal, accompanied by the appearance of the following lines in kern.log:
......... SLDT(SGDT) instruction cannot be used by applications.
This is because the User-Mode Instruction Prevention (UMIP) functionality on newer processors prevents these instructions from executing in user-mode. The issue should be fixed in the new Linux kernels version > 5.4. The workaround is to disable the UMIP functionality by loading the kernel with clearcpuid=514 option.
Hope this helps.
Firefly Project Team.