Simulator Support

This page documents any known quirks and gotchas in the various simulators.


Accessing bits of a vector doesn’t work:

dut.stream_in_data[2] <= 1

See “access_single_bit” test in examples/functionality/tests/

Synopsys VCS

Aldec Riviera-PRO

The $LICENSE_QUEUE environmental variable can be used for this simulator - this setting will be mirrored in the TCL license_queue variable to control runtime license checkouts.

Mentor Questa

Mentor Modelsim

Any ModelSim-PE or ModelSim-PE derivative (like ModelSim Microsemi, Altera, Lattice Edition) does not support the VHDL FLI feature. If you try to run with FLI enabled, you will see a vsim-FLI-3155 error:

** Error (suppressible): (vsim-FLI-3155) The FLI is not enabled in this version of ModelSim.

ModelSim DE and SE (and Questa, of course) supports the FLI.

Cadence Incisive


Support is preliminary.