FABulous Environment Variables

FABulous can use environment variables to configure options, paths and projects. We distinguish between two types of environment variables: global and project specific environment variables. Global environment variables are used to configure FABulous itself, while project specific environment variables are used to configure a specific FABulous project. All environment variables can be set in the shell before running FABulous or can be set via .env files.

Note

Environment variables can be set in the shell before running FABulous. Shell environment variables always have the highest priority.

Global Environment Variables

Global environment variables always start with FAB_ and are used to configure FABulous itself. To add a global .env file, create a file named .env in the root directory of the FABulous repository or use the --globalDotEnv command line argument when running FABulous. The following global environment variables are available:

Variable Name	Description	Default Value
FAB_ROOT	The root directory of the FABulous repository	The directory where the FABulous repository is located
FAB_FABULATOR_ROOT	The root directory of the FABulator repository	<None>
FAB_YOSYS_PATH	Path to Yosys binary	yosys (Uses global Yosys installation)
FAB_NEXTPNR_PATH	Path to Nextpnr binary	nextpnr-generic (Uses global Nextpnr installation)
FAB_IVERILOG_PATH	Path to Icarus Verilog binary	iverilog (Uses global Icarus Verilog installation)
FAB_VVP_PATH	Path to Verilog VVP binary	vvp (Uses global Verilog VVP installation)
FAB_GHDL_PATH	Path to GHDL binary	ghdl (Uses global GHDL installation)
FAB_PROJ_DIR	The root directory of the FABulous project	The directory where the FABulous project is located, given by command line
FAB_MODELS_PACK	The models pack for the project	Pointing to <project_dir>/Fabric/models_pack.<project_lang>
FAB_OSS_CAD_SUITE	Path to the oss-cad-suite installation	<None>
FAB_DEBUG	Enable debug mode	False
FAB_VERBOSE	Enable verbose mode	0
FAB_EDITOR	Set the editor to be used by the edit command	<None>
FAB_WINDOWS_WARNING_ACKNOWLEDGED	Suppress Windows compatibility warning (use at your own risk)	False

Project Specific Environment Variables

Project specific environment variables always start with FAB_PROJ_ and are used to configure a specific FABulous project. To add a project specific .env file, create a file named .env in the .FABulous directory of the FABulous project or use the --projectDotEnv command line argument when running FABulous. The following project specific environment variables are available:

Note

The project specific environment variables overwrite the global environment variables.

Variable Name	Description	Default Value
FAB_PROJ_LANG	RTL language used in FABulous project [verilog/vhdl]	verilog (default) or language specified by -w command line argument
FAB_SWITCH_MATRIX_DEBUG_SIGNAL	Generate debug signals in switch matrix RTL implementation [True/False]	True
FAB_PROJ_VERSION_CREATED	The version of FABulous used to create the project	Same as the version of FABulous-FPGA package installed
FAB_PROJ_VERSION	The current project version	Same as the version of FABulous-FPGA package installed