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Installation using GNU Autotools

Note 1: Usage of the GNU Autotools build flow will be deprecated as part of SystemC 3.1. It it recommended to use the CMake build system instead, see INSTALL.md.

Note 2: IEEE Std. 1666-2023 mandates C++17 as the baseline for SystemC implementations, see RELEASENOTES.md. Make sure to configure your compiler accordingly (see below).

Basic SystemC Installation

To install SystemC on a UNIX system, do the following steps:

  1. Change to the top level directory (e.g., systemc)

  2. Choose your compiler by setting the CXX environment variable (the configure script tries to guess the default compiler, if this step is omitted). If you use a POSIX-compatible shell (e.g., bash):

    export CXX="<compiler>"

    e.g. for GCC compilers

    export CXX=g++

    The Clang compiler is usually named clang++, thus e.g.

    export CXX=clang++

    When using a C shell (e.g., csh/tcsh), the syntax to set the environment variable is different:

    setenv CXX g++

    You can also specify an absolute path to the compiler of your choice. See also the Section Compilation and Linking Options below.

  3. Generate the configure script and the necessary Makefile.in files (only for git clone)

    Note: This step is required when using a git clone. It requires the GNU Autotools libtoolize, aclocal, automake, and autoconf. A SystemC release already contains the configuration executable so this step can be ignored.

    ./config/bootstrap

  4. Create a temporary directory, e.g.,

    mkdir objdir

  5. Change to the temporary directory, e.g.,

    cd objdir

  6. Configure the package for your system, e.g., (The configure script is explained below.)

    ../configure

    While the configure script is running, which takes a few moments, it prints messages to inform you of the features it is checking. It also detects the platform.

    Note: As IEEE Std. 1666-2023 mandates C++17 as the baseline for SystemC implementations, make sure you enable the compiler flag to select C++17, e.g.:

    ../configure 'CXXFLAGS=-std=c++17'

    Compiling this implementation for newer C++ standards is generally possible and tested at a best effort basis. Prefer C++17 for full IEEE Std. 1666-2023 conformance, see also SC_CPLUSPLUS macro documentation below.

    SystemC 3.0.0 includes a fixed-point package that is always built. When compiling your applications with fixed-point types, you still have to use compiler flag -DSC_INCLUDE_FX. Note that compile times might increase when using this compiler flag.

    In case you want to install the package in another place than the top level directory, configure the package e.g. as follows:

    ../configure --prefix=/usr/local/systemc

    Note: Make sure you have created the target directory before installing the package. Do not use /usr/local as a prefix, unless you follow the Unix/FHS directory layouts (see below).

    A fine grained configuration of the installation directories can be achieved via additional options, given to the configure script.

    By default, the files are installed directly to the PREFIX directory root and the library is installed to PREFIX/lib-<TARGETARCH>, depending on the current target architecture. This may be undesired in cases where the package is meant to be installed in a system-wide location as part of shared (default) library and include hierarchies (e.g. /usr/local, /usr, /opt, ...). To follow the Unix/FHS directory standards, you can use the following options:

      --with-unix-layout     use Unix directory layout for installation
                         [default=no]

    when "yes", the following (fine-grained) settings will be used:

      --includedir=DIR       C++ header files      [PREFIX/include]
  --libdir=DIR           object code libraries [EPREFIX/lib]
  --docdir=DIR           documentation root    [DATAROOTDIR/doc/systemc]

    The library destination itself can be further and separately configured by using the following option:

      --with-arch-suffix    add suffix to library installation directory
                        [default=-<TARGETARCH>]

    With this option, one can easily follow e.g. the "multi-arch" conventions on some platforms:

    ../configure --with-arch-suffix=32                # lib32
../configure --with-arch-suffix=/x86_64-linux-gnu # lib/x86_64-linux-gnu

    Several options are available to the configure script to modify the compiler configuration and the selection of certain features:

      --disable-shared       do not build shared library (libsystemc.so)
  --enable-debug         include debugging symbols
  --disable-optimize     disable compiler optimization
  --enable-pthreads      use POSIX threads for SystemC processes

    See the section on the general usage of the configure script and ../configure --help for more information.

    Note: When linking against a static library of SystemC with asynchronous update support enabled, you may need to explicitly link against the pthread library as well (-lpthread).

    Note: If you change the configuration after having compiled the package already, you should run a make clean before recompiling.

  7. Compile the package 

    make

    Note: The explicit make targets opt and debug, etc. have been removed in this package. Use the corresponding options to the configure script instead.

  8. At this point you may wish to verify the compiled package by testing the example suite.

    make check

    This will compile and run the examples in the subdirectory examples.

  9. Install the package

    make install

  10. You can now remove the temporary directory, .e.g,

    cd ..
rm -rf objdir

    Alternatively, you can keep the temporary directory to allow you to

    1. Experiment with the examples.
    2. Later uninstall the package.

    To clean up the temporary directory, enter:

    make clean

    To uninstall the package, enter:

    make uninstall

Running the Examples

Copies of the examples reside in the temporary directory - see step 7 for details on building and running them.

In addition, a copy of the example code resides in the directory examples at the highest level of the installation (or in the shared documentation install directory).

Use the Makefiles provided in the examples directory as templates for Makefiles you need for compiling your own examples.

Using the Configure Script

The configure shell script tries to determine the correct values for various system-dependent variables used during compilation. It uses these values to create a Makefile in each directory of the package. It also creates one or more .h files containing system-dependent definitions if needed. Then, it creates the following files:

  • config.status A shell script that you can run at another time to recreate the current configuration.

  • config.cache A file in which the configure test results are saved to speed up reconfiguration. Data is appended to the config.cache file. You can remove unwanted data.

  • config.log A file in which compiler output is saved. This is used to debug the configure script.

If you need to use other commands to successfully compile the package on your system, please try to determine if the configure script can be used for these commands. Then, send either a diff file or instructions about the commands you used to the e-mail address provided in the README file. This information will be used to improve the installation process in the next release.

The configure.ac file is provided in case you want to change or regenerate the configure script, for example to use a newer version of autoconf. The configure.ac file is used by the autoconf program to create the configure script.

Note for (key) developers:

In case you have changed the configure.ac file or one of the Makefile.am files:

  • Use

    make distclean

    to remove the generated configure script, the generated aclocal.m4 file and the generated Makefile.in files.

  • Use the config/bootstrap script to generate the configure script and the necessary Makefile.in files. This script makes use of the GNU Autotools aclocal, automake, and autoconf.

Compilation and Linking Options

Some systems require compilation or linking options that the configure script does not define. You can define the initial values for these options by setting them in your environment before running the configure script.

Instead of passing the variables via the environment, it is preferred to pass the values as options to the configure script, e.g.,:

../configure CXX=g++-9.3 LIBS=-lposix

Specifying the System Type

Some features cannot be automatically determined by configure unless it can detect the host type on which the package will run. If it prints a message that it cannot determine the host type, use the --host=TYPE option to define it. TYPE can either be a short system name or a canonical name with three fields:

 CPU-COMPANY-SYSTEM

See the config.sub file for details about the values of each field. If the config.sub file is not included in the package, the package does not need to know the host type.

If you are building compiler tools for cross-compiling, you can also use the --target=TYPE option to select the type of system for which the code is produced and the --build=TYPE option to select the type of system on which you are compiling the package.

Sharing Defaults

You can set the default values that configure scripts share by creating a site shell script called config.site. This file contains the default values for variables like CC, cache_file, and prefix. The configure script looks for the config.site file in the following search precedence:

  1. PREFIX/share/config.site
  2. PREFIX/etc/config.site

Alternatively, you can set the CONFIG_SITE environment variable to the site script path.

Note: The configure script for some systems does not look for a site script.

Operation Controls

The configure script recognizes the following additional options to control its operation:

--cache-file=FILE Use and save the test results in FILE instead of ./config.cache. Set FILE to /dev/null to disable caching when debugging configure.

--help Print a summary of configure options and exit.

--quiet --silent -q Do not print messages about checks being made. To suppress all normal output, redirect it to /dev/null. Error messages continue to print.

--srcdir=DIR Look for the package's source code in directory DIR. Typically configure determines the directory automatically.

--version Print the version of autoconf used to generate the configure script and exit.

Other options that are rarely used are available in the configure script. Use the --help option to print a list.

SystemC Library Configuration Switches

In addition to the explicitly selectable feature given as options to the configure script (see 1.), some aspects of the library implementation can be controlled via

  • preprocessor switches given during library build
  • preprocessor switches added while building a SystemC application
  • environment variables

The currently supported switches are documented in this section.

Preprocessor switches

Additional preprocessor switches for the library build can be passed to the configure script via the CXXFLAGS variable:

  ../configure CXXFLAGS="-DSC_OVERRIDE_DEFAULT_STACK_SIZE=0x80000"

  • SC_CPLUSPLUS Override automatically detected C++ standard support

    This setting allows downgrading the assumed version of the underlying C++ standard on the current platform. By default, the compiler-selected version is chosen.

    Currently known values are:

    • SC_CPLUSPLUS=201703L (C++17, ISO/IEC 14882:2017)
    • SC_CPLUSPLUS=202002L (C++20, ISO/IEC 14882:2020)
    • SC_CPLUSPLUS=202302L (C++23, ISO/IEC 14882:2023)

    Note: This symbol needs to be consistently defined in the library and any application linking against the built library.

  • SC_DEFAULT_WRITER_POLICY=<sc_writer_policy> Override default value for the signal writer policy

    This setting allows deactivating the multiple writer checks for sc_signals at (application) compile time. This mechanism supersedes the old environment variable SC_SIGNAL_WRITE_CHECK (see below).

    Supported values:

    • SC_ONE_WRITER (default)
    • SC_MANY_WRITERS (allow multiple writers in different deltas)
    • SC_UNCHECKED_WRITERS (non-standard, disable all checks)

    Note: Only effective when building an application. Note: This setting needs to be consistently set across all translation units of an application.

  • SC_DISABLE_VCD_SCOPES Disable grouping of VCD trace variables in hierarchical scopes by default

    Note: Only effective during library build. See : Environment variable SC_VCD_SCOPES

  • SC_DISABLE_COPYRIGHT_MESSAGE Do not print the copyright message when starting the application

    Note 1: This does not remove the copyright from the binary. sc_core::sc_copyright() still works as expected.

    Note 2: Only effective during library build. See : Environment variable SC_COPYRIGHT_MESSAGE

  • SC_ENABLE_ASSERTIONS Always enable the sc_assert expressions

    Some build systems define NDEBUG by default in optimised build configurations. As a result, the SystemC assertion macro sc_assert() is disabled (similar to the C assert() macro). By defining this preprocessor symbol (when building the library and/or an application), the sc_assert() checks are always enabled, irrespectively of the definition of NDEBUG.

  • SC_INCLUDE_FX Enable SystemC fixed-point data-types

    To improve compilation times, the fixed-point data-types are not enabled by default in an SystemC application. Define this symbol before including the SystemC header in your application, if you want to use the SystemC fixed-point types.

    Note: Is by default always defined during the library build to enable later use of the fixed-point data-types in an application.

    Note: Can be optionally set per translation unit in an application.

  • SC_INCLUDE_WINDOWS_H Explicitly include <windows.h> header from <systemc> header

    Previous versions of SystemC always included the full <windows.h> header on all Windows platforms. This adds unnecessary bloat to many SystemC applications, increasing compilation times. If you rely on the inclusion of the <windows.h> header in your application, you can add this symbol to the list of preprocessor switches for your compiler.

    Note: Only effective when building an application.

  • SC_INCLUDE_EXTRA_STD_HEADERS Include <cstring> and <sstream> headers from <systemc> header

    Previous versions of SystemC implicitly included the <cstring> and <sstream> headers on all platforms without depending on their contents. If you rely on the inclusion of these headers in your application, you can add this symbol to the list of preprocessor switches for your compiler.

    Note: Only effective when building an application.

  • SC_ALLOW_MACROS_WITHOUT_SEMICOLON Allow using (process) macros without terminating semicolon

    Previous versions of SystemC allowed using some macros without a trailing semicolon. This is no longer supported by default. Defining the above macro restores the old behavior. Affected macros: SC_METHOD, SC_(C)THREAD.

    Note: Only effective when building an application.

  • SC_OVERRIDE_DEFAULT_STACK_SIZE=<size> Define the default stack size used for SystemC (thread) processes

    Note: Only effective during library build.

  • SC_USE_STD_STRING Define sc_string symbol as an alias to std::string

    Pre-IEEE-1666 versions of SystemC included an sc_string class for string objects. This class has been superseeded by std::string these days.

  • SC_WIN_DLL Build (against) a DLL build of SystemC (Windows/MSVC only)

    Needs to be set when building a SystemC DLL on Windows, as well as when building an application/library to be linked against a DLL version of SystemC.

Influential environment variables

Currently, three environment variables are checked at library load time and influence the SystemC library's behavior:

  • SC_COPYRIGHT_MESSAGE=DISABLE Run-time alternative to SC_DISABLE_COPYRIGHT_MESSAGE (see above).

  • SC_SIGNAL_WRITE_CHECK=DISABLE, SC_SIGNAL_WRITE_CHECK=CONFLICT Run-time alternative to SC_DEFAULT_WRITER_POLICY (see above).

    • DISABLE = disable all checks for conflicting writes (SC_UNCHECKED_WRITERS)
    • CONFLICT = detect conflicting writes within the same evaluation phase (SC_MANY_WRITERS)

  • SC_DEPRECATION_WARNINGS=DISABLE Do not issue warnings about using deprecated features as of IEEE Std. 1666-2011.

  • SC_VCD_SCOPES=DISABLE, SC_VCD_SCOPES=ENABLE Run-time configuration of hierarchically scoped names in VCD trace files (see SC_DISABLE_VCD_SCOPES).

Usually, it is not recommended to use any of these variables in new or on-going projects. They have been added to simplify the transition of legacy code.