| .. _simulator-support: |
|
|
| ***************** |
| Simulator Support |
| ***************** |
|
|
| This page lists the simulators that cocotb can be used with |
| and documents specifics, limitations, workarounds etc. |
|
|
| In general, cocotb can be used with any simulator supporting the industry-standard VPI, VHPI or FLI interfaces. |
| However, in practice simulators exhibit small differences in behavior that cocotb mostly takes care of. |
|
|
| If a simulator you would like to use with cocotb is not listed on this page |
| open an issue at the `cocotb GitHub issue tracker <https://github.com/cocotb/cocotb/issues>`_. |
|
|
|
|
| .. _sim-icarus: |
|
|
| Icarus Verilog |
| ============== |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``icarus``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=icarus |
|
|
| .. note:: |
| A working installation of `Icarus Verilog <http://iverilog.icarus.com/>`_ is required. |
| You can find installation instructions `in the Icarus Verilog Installation Guide <https://iverilog.fandom.com/wiki/Installation_Guide>`_. |
|
|
| .. _sim-icarus-accessing-bits: |
|
|
| Accessing bits in a vector |
| -------------------------- |
|
|
| Accessing bits of a vector directly was not possible until (including) version 10.3: |
|
|
| .. code-block:: python3 |
|
|
| dut.stream_in_data[2].value = 1 |
|
|
| See also https://github.com/steveicarus/iverilog/issues/323. |
|
|
| .. _sim-icarus-waveforms: |
|
|
| Waveforms |
| --------- |
|
|
| Icarus Verilog can produce waveform traces in the FST format, the native format of GTKWave. |
| FST traces are much smaller and more efficient to write than VCD, but requires the use of GTKWave. |
|
|
| To enable FST tracing, set :make:var:`WAVES` to ``1``. |
|
|
| .. code-block:: bash |
|
|
| make SIM=icarus WAVES=1 |
|
|
| .. _sim-icarus-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:icarus <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aicarus>`_ |
|
|
|
|
| .. _sim-verilator: |
|
|
| Verilator |
| ========= |
|
|
| .. warning:: |
|
|
| Verilator is in the process of adding more functionality to its VPI interface, which is used by cocotb to access the design. |
| Therefore, Verilator support in cocotb is currently experimental. |
| Some features of cocotb may not work correctly or at all. |
|
|
| **cocotb only supports Verilator 5.006 and later.** |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``verilator``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=verilator |
|
|
| .. note:: |
| A working installation of `Verilator <https://www.veripool.org/verilator/>`_ is required. |
| You can find installation instructions `in the Verilator documentation <https://verilator.org/guide/latest/install.html>`_. |
|
|
| One major limitation compared to standard Verilog simulators is that it does not support delayed assignments when accessed from cocotb. |
|
|
| To run cocotb with Verilator, you need ``verilator`` in your PATH. |
|
|
| .. versionadded:: 1.3 |
|
|
| .. versionchanged:: 1.5 Improved cocotb support and greatly improved performance when using a higher time precision. |
|
|
| Coverage |
| -------- |
|
|
| To enable :term:`HDL` code coverage, add Verilator's coverage option(s) to the :make:var:`EXTRA_ARGS` make variable, for example: |
|
|
| .. code-block:: make |
|
|
| EXTRA_ARGS += --coverage |
|
|
| This will result in coverage data being written to :file:`coverage.dat`. |
|
|
| .. _sim-verilator-waveforms: |
|
|
| Waveforms |
| --------- |
|
|
| To get waveforms in VCD format, add Verilator's trace option(s) to the |
| :make:var:`EXTRA_ARGS` make variable, for example in a Makefile: |
|
|
| .. code-block:: make |
|
|
| EXTRA_ARGS += --trace --trace-structs |
|
|
| To set the same options on the command line, use ``EXTRA_ARGS="--trace --trace-structs" make ...``. |
| A VCD file named ``dump.vcd`` will be generated in the current directory. |
|
|
| Verilator can produce waveform traces in the FST format, the native format of GTKWave. |
| FST traces are much smaller and more efficient to write, but require the use of GTKWave. |
|
|
| To enable FST tracing, add ``--trace-fst`` to :make:var:`EXTRA_ARGS` as shown below. |
|
|
| .. code-block:: make |
|
|
| EXTRA_ARGS += --trace-fst --trace-structs |
|
|
| The resulting file will be :file:`dump.fst` and can be opened by ``gtkwave dump.fst``. |
|
|
| .. _sim-verilator-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:verilator <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Averilator>`_ |
|
|
|
|
| .. _sim-vcs: |
|
|
| Synopsys VCS |
| ============ |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``vcs``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=vcs |
|
|
| cocotb currently only supports :term:`VPI` for Synopsys VCS, not :term:`VHPI`. |
|
|
| .. _sim-vcs-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:vcs <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Avcs>`_ |
|
|
|
|
| .. _sim-aldec: |
| .. _sim-riviera: |
|
|
| Aldec Riviera-PRO |
| ================= |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``riviera``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=riviera |
|
|
| .. note:: |
|
|
| On Windows, do not install the C++ compiler, i.e. unselect it during the installation process of Riviera-PRO. |
| (A workaround is to remove or rename the ``mingw`` directory located in the Riviera-PRO installation directory.) |
|
|
| .. deprecated:: 1.4 |
|
|
| Support for Riviera-PRO was previously available with ``SIM=aldec``. |
|
|
| The :envvar:`LICENSE_QUEUE` environment variable can be used for this simulator – |
| this setting will be mirrored in the TCL ``license_queue`` variable to control runtime license checkouts. |
| |
| |
| .. _sim-aldec-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:riviera <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Ariviera>`_ |
|
|
|
|
| .. _sim-activehdl: |
|
|
| Aldec Active-HDL |
| ================ |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``activehdl``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=activehdl |
|
|
| .. warning:: |
|
|
| cocotb does not work with some versions of Active-HDL (see :issue:`1494`). |
|
|
| Known affected versions: |
|
|
| - Aldec Active-HDL 10.4a |
| - Aldec Active-HDL 10.5a |
|
|
| .. _sim-activehdl-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:activehdl <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aactivehdl>`_ |
|
|
|
|
| .. _sim-questa: |
|
|
| Mentor/Siemens EDA Questa |
| ========================= |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``questa``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=questa |
|
|
| Starting with Questa 2022.3 and cocotb 1.7 users with VHDL toplevels can choose between two communication interfaces between Questa and cocotb: the proprietary FLI and VHPI. |
| For backwards-compatibility cocotb defaults to FLI. |
| Users can choose VHPI instead by setting the :envvar:`VHDL_GPI_INTERFACE` environment variable to ``vhpi`` before running cocotb. |
|
|
| For more information, see :ref:`sim-modelsim`. |
|
|
| .. _sim-questa-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:questa <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aquesta>`_ |
|
|
|
|
| .. _sim-modelsim: |
|
|
| Mentor/Siemens EDA ModelSim |
| =========================== |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``modelsim``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=modelsim |
|
|
| Any ModelSim PE or ModelSim PE derivatives (like the ModelSim Microsemi, Intel, Lattice Editions) do not support the VHDL :term:`FLI` feature. |
| If you try to use them with :term:`FLI`, you will see a ``vsim-FLI-3155`` error: |
|
|
| .. code-block:: bash |
|
|
| ** Error (suppressible): (vsim-FLI-3155) The FLI is not enabled in this version of ModelSim. |
|
|
| ModelSim DE and SE (and Questa, of course) support the :term:`FLI`. |
|
|
| In order to start ModelSim or Questa with the graphical interface and for the simulator to remain active after the tests have completed, set :make:var:`GUI=1`. |
| If you have previously launched a test without this setting, you might have to delete the :make:var:`SIM_BUILD` directory (``sim_build`` by default) to get the correct behavior. |
|
|
| .. _sim-modelsim-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:modelsim <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Amodelsim>`_ |
|
|
|
|
| .. _sim-incisive: |
|
|
| Cadence Incisive |
| ================ |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``ius``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=ius |
|
|
| For more information, see :ref:`sim-xcelium`. |
|
|
| .. _sim-incisive-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:ius <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aius>`_ |
|
|
|
|
| .. _sim-xcelium: |
|
|
| Cadence Xcelium |
| =============== |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``xcelium``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=xcelium |
|
|
| The simulator automatically loads :term:`VPI` even when only :term:`VHPI` is requested. |
|
|
| Testing designs with VHDL toplevels is only supported with Xcelium 23.09.004 and newer. |
|
|
| .. _sim-xcelium-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:xcelium <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Axcelium>`_ |
|
|
|
|
| .. _sim-ghdl: |
|
|
| GHDL |
| ==== |
|
|
| .. warning:: |
|
|
| GHDL support in cocotb is experimental. |
| Some features of cocotb may not work correctly or at all. |
| At least GHDL 2.0 is required. |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``ghdl``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=ghdl |
|
|
| .. note:: |
| A working installation of `GHDL <https://ghdl.github.io/ghdl/about.html>`_ is required. |
| You can find installation instructions `in the GHDL documentation <https://ghdl.github.io/ghdl/getting.html>`_. |
|
|
| Noteworthy is that despite GHDL being a VHDL simulator, it implements the :term:`VPI` interface. |
|
|
| To specify a VHDL architecture to simulate, set the ``ARCH`` make variable to the architecture name. |
|
|
| .. _sim-ghdl-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:ghdl <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Aghdl>`_ |
|
|
|
|
| .. _sim-ghdl-waveforms: |
|
|
| Waveforms |
| --------- |
|
|
| To get waveforms in VCD format, set the :make:var:`SIM_ARGS` option to ``--vcd=anyname.vcd``, |
| for example in a Makefile: |
|
|
| .. code-block:: make |
|
|
| SIM_ARGS+=--vcd=anyname.vcd |
|
|
| The option can be set on the command line, as shown in the following example. |
|
|
| .. code-block:: bash |
|
|
| SIM_ARGS=--vcd=anyname.vcd make SIM=ghdl |
|
|
| A VCD file named :file:`anyname.vcd` will be generated in the current directory. |
|
|
| :make:var:`SIM_ARGS` can also be used to pass command line arguments related to :ref:`other waveform formats supported by GHDL <ghdl:export_waves>`. |
|
|
|
|
| .. _sim-nvc: |
|
|
| NVC |
| === |
|
|
| .. note:: |
|
|
| NVC version **1.11.0** or later is required. |
|
|
| In order to use this simulator, set :make:var:`SIM` to ``nvc``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=nvc |
|
|
| .. _sim-nvc-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:nvc <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Anvc>`_ |
|
|
| Coverage |
| -------- |
|
|
| To enable code coverage, add ``--cover`` to :make:var:`SIM_ARGS`, for example |
| in a Makefile: |
|
|
| .. code-block:: make |
|
|
| SIM_ARGS += --cover |
|
|
| Specifying types of coverage is also supported. |
| For example, to collect statement and branch coverage: |
|
|
| .. code-block:: make |
|
|
| SIM_ARGS += --cover=statement,branch |
|
|
| The ``covdb`` files will be placed in the :make:var:`RTL_LIBRARY` subdirectory of :make:var:`SIM_BUILD`. |
| For instructions on how to specify coverage types and produce a report, refer to `NVC's code coverage documentation <https://www.nickg.me.uk/nvc/manual.html#CODE_COVERAGE>`_. |
|
|
| .. _sim-nvc-waveforms: |
|
|
| Waveforms |
| --------- |
|
|
| To get waveforms in FST format, set the :make:var:`SIM_ARGS` option to ``--wave=anyname.fst``, for example in a Makefile: |
|
|
| .. code-block:: make |
|
|
| SIM_ARGS += --wave=anyname.fst |
|
|
| :make:var:`SIM_ARGS` can also be used to set the waveform output to VCD by adding ``--format=vcd``. |
|
|
|
|
| .. _sim-cvc: |
|
|
| Tachyon DA CVC |
| ============== |
|
|
| In order to use `Tachyon DA <http://www.tachyon-da.com/>`_'s `CVC <https://github.com/cambridgehackers/open-src-cvc>`_ simulator, |
| set :make:var:`SIM` to ``cvc``: |
|
|
| .. code-block:: bash |
|
|
| make SIM=cvc |
|
|
| Note that cocotb's makefile is using CVC's interpreted mode. |
|
|
| .. _sim-cvc-issues: |
|
|
| Issues for this simulator |
| ------------------------- |
|
|
| * `All issues with label category:simulators:cvc <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+-label%3Astatus%3Aduplicate+label%3Acategory%3Asimulators%3Acvc>`_ |
|
|
