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The MaSoCist environment

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[email protected]

(Martin's SoC Instancing and Simulation/Synthesis Toolchain)

a.k.a. "Make it hurt!"

The MaSoCist distribution enables you to quickly design, maintain, document and automatically create a family of Soft core featured System on Chip solutions. It may therefore hurt less for you.

The MaSoCist is currently supported as docker image for local or cloud deployment only (previous LXC support dropped). This opensource-version currently supports:

  • Co-Simulation with GHDL
  • A limited set of virtual boards and CPU architectures
  • Compiling source code for various architectures
  • Simple, hand-woven continuous integration testing for hardware/software

Synthesis in the cloud is not yet supported. Integration is planned, once VHDL open source synthesis is sufficiently tested. However, all VHDL code is synthesizeable for typical FPGA scenarios.

Quick evaluation

Here's a short howto to set up an environment ready to play with. For example, running a virtual instance of a RISC-V with UART console.

You can try this (for instance) in the browser at

Register yourself a Docker account login and start playing in your online sandbox (time limit applies). You'll need to build and copy some files from contrib/docker to the remote Docker machine instance.

Add a new machine instance in the left panel. Then run the container:

docker run -it hackfin/masocist

(wait a bit, then when you see the Virtual COM message, proceed:)

wget && sh && make all run-pyrv32

After building the relevant tools, the virtual processor will boot and the terminal is fired up to talk to it. When you see the 'Booting beatrix' message, you should get a prompt. Try the 'h' command followed by return to get help:

# h

When you exit minicom by hitting Ctrl+A, then q, the simulation will be terminated. Because it is a cycle accurate hardware description of synthesizeable hardware, it will run a few thousand times slower than a real CPU.

The benefit: You can trace down to each little bit what the entire SoC is doing. If you forget to initialize something in software (which is a classic error to lead to random behaviour in the real world) you will see it immediately in the trace waveforms.

Building from scratch

Because dependencies have become complex, the only supported method to build the MaSoCist environment is currently using the Dockerfile supplied in contrib/docker.

Run 'make dist' inside contrib/docker, this will create a file Copy the following files to the Docker working directory (in the above docker playground this works by dragging them onto the Playground browser shell window):


Build the container and run it:

docker build . -t masocist

docker run -it -v/root:/usr/local/src masocist

Copy to the Docker machine and run, inside the running container's home dir (/home/masocist):

sudo sh /usr/local/src/

Now pull and build all necessary packages:

make all

Run the virtual CPU demo, for example for pyrv32 or neo430:

make clean run-pyrv32

make clean run-neo430

If nothing went wrong, the simulation for the selected CPU will be built and started with a virtual UART and SPI simulation. A minicom terminal will connect to that UART and you'll be able to speak to the 'bare metal' shell, for example, you can dump the content of the virtual SPI flash by:

s 0 1

Again, use Ctrl+A followed by q to terminate the console and simulation.

Building a (virtual) board

Enter the masocist source directory, typically in $HOME/src/vhdl/masocist.

  1. Choose a configuration from an available set:

    make which
  2. select a configuration, e.g. 'virtualboard':

    make virtualboard

This would build all $(BUILD_DUTIES), which are typically 'sim' for Simulation:

make all

If you change the configuration, you may have to clean the simulation (in worst case twice, if the kconfig tool decides to reconfigure):

make clean all
  1. Build files for synthesis:

    make -C syn clean all
  2. Open the project in syn/$(FPGA\_VENDOR)/$(PLATFORM)

If files need to be added, you may use the TCL scripts that are generated when running 'make' for synthesis.

  1. Synthesize and hope for success :-)

Important: The build procedure for simulation builds the source differently than for synthesis (-DSIMULATION flag). Make sure to rebuild explicitely for synthesis, otherwise your system may boot up incorrectly with the simulation specific program code.


The licensing of the MaSoCist distribution depends on its package tag.

As the author has made the experience, that opensource licenses are not always respected when it comes to hardware designs, there is no such thing as GPL (Gnu Public License) for this code, plus, it would very much complicate development under a dual licensing scheme.

If you have received an 'opensource' distribution, the following rules apply:


  • You can use it for educational purposes or non-commercial home projects
  • You will not get much free support, but you may of course feed back bugs
  • You are encouraged to publish your changes, but noone will force you to it


  • If you use the code in a commercial environment, you are free to do so, but you are required to publish changes made to the MaSoCist code base, including your own code that depends on MaSoCist functionality.
  • If you are making a product that you are re-licensing or re-selling to others, you will need to acquire a license for the IP you use.

If you wish to have a maintained custom package, you will have to sign up for a license agreement. This entitles you for a distribution tag. In this case, you are completely free to keep further development proprietary, EXCEPT changes made to the ghdlex package. Note that you also have to follow the GHDL license agreements for distribution of simulation executables.


Simulation of some boards may require libraries that are not included in the MaSoCist, because they are vendor specific. There may be several solutions:

  • Obtain necessary files from your local FPGA tool installation and create a GHDL library. Use the -P option to GHDL to specify the search path to the GHDL config file.
  • Use a virtual board config that is fully vendor IP independent

For example, when you receive an error message like this:

  ../hdl/plat/breakout_top.vhdl:16:9: cannot find resource library "machxo2"

you have to create a file lattice/ somewhere using the rule:

MACHXO2_VHDL = $(wildcard $(LATTICE_SIM)/machxo2/src/*.vhd)

lattice/ $(MACHXO2_VHDL)
        [ -e lattice ] || mkdir lattice
        ghdl -i --workdir=lattice --work=machxo2 $(MACHXO2_VHDL)

where LATTICE_SIM is the directory of your simulation VHDL files, like:


Then set the LIBGHDL variable in vendor/default/ to the directory where you created lattice/, like:

LIBGHDL = $(HOME)/src/vhdl/lib/ghdl


Note: The MaSoCist setup allows you to configure plenty of options that may NOT WORK and will require you to look into implementation details. Also, it may happen that some cores or options are just not supported by the distribution you have. Especially the opensource version is somewhat restricted to minimize support.

Therefore, a few thumb rules:

  • Altering the peripheral I/O is safe.
  • When changing the 'SoC device description', also check if 'Enable map prefix' needs to be set. This is described in detail in the developer documentation.
  • For the Zealot CPU, you can make changes in the 'ZPU configuration' to some extent (see also developer documentation)
  • Avoid changes in the TAP configuration. It has just been tuned that it works.


For all further information, see doc/directory or visit the MaSoCist home page at:

There are two ways to build the documentation:

  • Opensource: Install the dblatex package and run

    dblatex opensource.xml

    Not all documentation can be built using this scheme.

  • Full SDK: Simply run 'make' and the documentation for your platform will be built automatically.

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