Thank you for your replies. I am looking into GHDL now.
Xilinx claims to support VHDL-2008, but elaboration fails on simple stuff (e.g. to_string() and maximum()) with an error saying, they do not support the given construct for simulation yet:
ERROR: [XSIM 43-4187] File “/home/brix/Projects/github/OSVVM/AlertLogPkg.vhd” Line 499 : The “Vhdl 2008 Predefined Function MAXIMUM” is not supported yet for simulation.
