IOb-SoC

IOb-SoC is a System-on-Chip (SoC) template comprising an open-source RISC-V processor (picorv32), an internal SRAM memory subsystem, a UART (iob-uart), and an optional interface to an external memory. If the external memory interface is selected, an instruction L1 cache, a data L1 cache and a shared L2 cache are added to the system. The L2 cache communicates with a 3rd party memory controller IP (typically a DDR controller) using an AXI4 master bus.

Operating Systems

IOb-SoC can be used in Linux Operating Systems. The following instructions work for CentOS 7 and Ubuntu 18.04, 20.04 and 22.04 LTS.

Nix environment

Instead of manually installing the dependencies above, you can use nix-shell to run IOb-SoC in a Nix environment with all dependencies available except for Vivado and Quartus.

• Run nix-shell from the IOb-SoC root directory to install and start the environment with all the required dependencies.

Clone the repository

The first step is to clone this repository. IOb-SoC uses git sub-module trees, and GitHub will ask for your password for each downloaded module if you clone by https. To avoid this, setup GitHub access with ssh and type:

git clone --recursive [email protected]:IObundle/iob-soc.git
cd iob-soc

Alternatively, you can still clone this repository using https if you cache your credentials before cloning the repository, using: git config --global credential.helper 'cache --timeout=<time_in_seconds>'

Configure your SoC

To configure your system edit the config.mk file, which can be found at the repository root. This file has the system configuration variables; hopefully, each variable is explained by a comment.

Set environment variables for local or remote building and running

The various simulators, FPGA compilers and FPGA boards may run locally or remotely. For running a tool remotely, you need to set two environmental variables: the server logical name and the server user name. Consider placing these settings in your .bashrc file, so that they apply to every session.

Set up the remote simulator server

Using open-source simulator Icarus Verilog as an example, note that in hardware/simulation/icarus/Makefile, the variable for the server logical name, SIM_SERVER, is set to IVSIM_SERVER, and the variable for the user name, SIM_USER, is set to IVSIM_USER. If you do not set these variables the simulator will run locally. To run the simulator on server mysimserver.myorg.com as user ivsimuser, set the following environmental variables beforehand:

export IVSIM_SERVER=ivsimserver.myorg.com
export IVSIM_USER=ivsimuser

Set up the remote FPGA toolchain and board servers

Using the CYCLONEV-GT-DK board as an example, note that in hardware/fpga/quartus/CYCLONEV-GT-DK/Makefile the variable for the FPGA tool server logical name, FPGA_SERVER, is set to QUARTUS_SERVER, and the variable for the user name, FPGA_USER, is set to QUARTUS_USER; the variable for the board server, BOARD_SERVER, is set to CYC5_SERVER, and the variable for the board user, BOARD_USER, is set to CYC5_USER. As in the previous example, set these variables as follows:

export QUARTUS_SERVER=quartusserver.myorg.com
export QUARTUS_USER=quartususer
export CYC5_SERVER=cyc5server.myorg.com
export CYC5_USER=cyc5username

In each remote server, the environment variables for the executable paths and license servers used must be defined as in the following example:

export QUARTUSPATH=/path/to/quartus
export VIVADOPATH=/path/to/vivado
...
export [email protected];lic_or_dat_file

Simulate the system

To simulate IOb-SoC, the simulator must be installed, either locally or remotely, and must have a run directory under the hardware/simulation directory, such as the hardware/simulation/icarus directory. To simulate, type:

make [sim-run] [SIMULATOR=<simulator directory name>] [<control parameters>]

<simulator directory name> is the name of the simulator's run directory,

<control parameters> are system configuration parameters passed in the command line, overriding those in the config.mk file. Example control parameters are INIT_MEM=0 RUN_EXTMEM=1. For example,

make sim-run SIMULATOR=icarus INIT_MEM=0 RUN_EXTMEM=1

To visualise simulation waveforms use the VCD=1 control parameter. It will open the Gtkwave waveform visualisation program.

To clean simulation generated files, type:

make sim-clean [SIMULATOR=<simulator directory name>] 
# Example
make sim-clean SIMULATOR=icarus

For more details, read the Makefile in each simulator directory. The Makefile includes the Makefile segment simulation.mk, which contains statements that apply to any simulator. In turn, simulation.mk includes the Makefile segment hardware.mk, which contains targets common to all hardware tools. The hardware.mk includes config.mk, which contains main system parameters. The Makefile in the simulator's directory, with the segments recursively included as described, is construed as a single large Makefile.

Emulate the system on PC

If there are embedded software compilation or runtime issues you can emulate the system on a PC to debug the issues. To emulate IOb-SoC's embedded software on a PC, type:

make pc-emul [<control parameters>]

where <control parameters> are system configuration parameters passed in the command line, overriding those in the config.mk file. Example control parameters are INIT_MEM=0 RUN_EXTMEM=1. For example,

make pc-emul INIT_MEM=0 RUN_EXTMEM=1

To clean the PC compilation generated files, type:

make pc-emul-clean

For more details, read the Makefile in the software/pc-emul directory. As explained for the simulation make file, note the Makefile segments recursively included.

Build and run on FPGA board

To build and run IOb-SoC on an FPGA board, the FPGA design tools must be installed, either locally or remotely, the board must be attached to the local host or to a remote host, and each board must have a build directory under the hardware/fpga/<tool> directory, for example the hardware/fpga/vivado/BASYS3 directory. The FPGA tools and board hosts may be different.

To build only, type

make fpga-build [BOARD=<board directory name>] [<control parameters>]

where <board directory name> is the name of the board's run directory, and <control parameters> are system configuration parameters passed in the command line, overriding those in the config.mk file. For example,

make fpga-build BOARD=BASYS3 INIT_MEM=0 RUN_EXTMEM=1

For more details read the Makefile in the board directory, and follow the recursively included Makefile segments as explained before.

To build and run, type:

make fpga-run [BOARD=<board directory name>] [<control parameters>]

The FPGA is loaded with the configuration bitstream before running. However, this step is skipped if the bitstream checksum matches that of the last loaded bitstream, kept in file /tmp/<board directory name>.load. If, for some reason, the run gets stuck, you may interrupt it with Ctr-C. Then, you may try again forcing the bitstream to be reloaded using control parameter FORCE=1.

If many users are trying to run the same FPGA board they will be queued in file /tmp/<board directory name>.queue. Users will orderly load their bitstream onto the board and start running it. After a successful run or Ctr-C interrupt, the user is de-queued.

To clean the FPGA compilation generated files, type

make fpga-clean [BOARD=<board directory name>]

Compile the documentation

To compile documents, the LaTeX document preparation software must be installed. Each document that can be compiled has a build directory under the document directory. Currently there are two document build directories: presentation and pb (product brief). The document to build is specified by the DOC control parameter. To compile the document, type:

make doc [DOC=<document directory name>]

To clean the document's build directory, type:

make doc-clean [DOC=<document directory name>]

For more details, read the Makefile in each document's directory, and follow the recursively included Makefile segments as explained before.

Testing

Simulation test

To run a series of simulation tests on the simulator selected by the SIMULATOR variable, type:

make sim-test [SIMULATOR=<simulator directory>]

The above command produces a test log file called test.log in the simulator's directory. The test.log file is compared with the test.expected file, which resides in the same directory; if they differ, the test fails; otherwise, it passes.

To run the series of simulation tests on all supported simulators, type:

make test-sim 

To clean the files produced when testing all simulators, type:

make test-sim-clean

Board test

To compile and run a series of board tests on the board selected by the BOARD variable, type:

make fpga-test [BOARD=<board directory name>]

The above command produces a test log file called test.log in the board's directory. The test.log file is compared with the test.expected file, which resides in the same directory; if they differ, the test fails; otherwise, it passes.

To run the series of board tests on all supported boards, type:

make test-fpga 

To clean the files produced when testing all boards, type:

make test-fpga-clean

Documentation test

To compile and test the document selected by the DOC, variable, type:

make doc-test [DOC=<document directory name>]

The resulting Latex .aux file is compared with a known-good .aux file. If the match the test passes; otherwise it fails.

To test all supported documents, type:

make test-doc

To clean the files produced when testing all documents, type:

make test-doc-clean

Total test

To run all simulation, FPGA board and documentation tests, type:

make test

Cleaning

The following command will clean the selected simulation, board and document directories, locally and in the remote servers:

make clean

Instructions for Installing the RISC-V GNU Compiler Toolchain

Get sources and checkout the supported stable version

git clone https://github.com/riscv/riscv-gnu-toolchain
git checkout 2022.06.10

Prerequisites

For the Ubuntu OS and its variants:

sudo apt install autoconf automake autotools-dev curl python3 python2 libmpc-dev libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo gperf libtool patchutils bc zlib1g-dev libexpat-dev

For CentOS and its variants:

sudo yum install autoconf automake python3 python2 libmpc-devel mpfr-devel gmp-devel gawk  bison flex texinfo patchutils gcc gcc-c++ zlib-devel expat-devel

Installation

cd riscv-gnu-toolchain
./configure --prefix=/path/to/riscv --enable-multilib
sudo make -j$(nproc)

This will take a while. After it is done, type:

export PATH=$PATH:/path/to/riscv/bin

The above command should be added to your ~/.bashrc file, so that you do not have to type it on every session.