Installation Guide¶
Icarus Verilog may be installed from source code (either from git or a
released tar/zip file), or from pre-packaged binary distributions. If you
don’t have a need for the very latest, and prepackaged binaries are available,
that is the easiest place to start.
Installation From Source¶
Icarus is developed for Unix-like environments but can also be compiled on Windows systems using the Cygwin/MSYS2 environments or MinGW compilers. The following instructions are the common steps for obtaining the Icarus Verilog source code, compiling, installing, and checking the compiled code is working properly. Note that there are pre-compiled and/or prepackaged versions for a variety of systems, so if you find an appropriate packaged version, then that is the easiest way to install.
The source code for Icarus is stored under the git source code control
system. You can use git to get the latest development head or the latest of
a specific branch. Stable releases are placed on branches, and in particular V12
stable releases are on the branch “v12-branch” To get the development version
of the code follow these steps:
% git config --global user.name "Your Name Goes Here"
% git config --global user.email you@yourpublicemail.example.com
% git clone https://github.com/steveicarus/iverilog.git
The first two lines are optional and are used to tell git who you are. This information is important if/when you submit a patch. We suggest that you add this information now so you don’t forget to do it later. The clone will create a directory, named iverilog, containing the source tree, and will populate that directory with the most current source from the HEAD of the repository.
Change into this directory using:
% cd iverilog
Normally, this is enough as you are now pointing at the most current development code, and you have implicitly created a branch master that tracks the development head. However, If you want to actually be working on the v12-branch (the branch where the latest V12 patches are) then you checkout that branch with the command:
% git checkout --track -b v12-branch origin/v12-branch
This creates a local branch that tracks the v12-branch in the repository, and switches you over to your new v12-branch. The tracking is important as it causes pulls from the repository to re-merge your local branch with the remote v12-branch. You always work on a local branch, then merge only when you push/pull from the remote repository.
The choice between the development branch and the latest released branch depends on your stability requirements. The released branch will only get bug fixes. It will not get any enhancements or changes in the compiler output format. Unlike many project the development branch is fairly stable with only occasional periods of instability. We do most of our big changes in side branches and only merge them into the development branch when they are clean.
Now that you’ve cloned the repository and optionally selected the branch you want to work on, your local source tree may later be synced up with the development source by using the git command:
% git pull
The git system remembers the repository that it was cloned from, so you don’t need to re-enter it when you pull.
To build the configure script and hash files you need to run the following:
% sh autoconf.sh
% cd ..
This is not need for the released tar/zip files since they already contain
these files. You only need to run this once after cloning. If you are missing
autoconf or gperf then the script will fail:
Autoconf in root...
autoconf.sh: 10: autoconf: not found
Precompiling lexor_keyword.gperf
autoconf.sh: 13: gperf: not found.
You will need to install the autoconf and gperf tools before you can
continue.
The other way to get the source code is to download a released tar/zip file:
% tar -xvzf v13_0.tar.gz
or
% unzip v13_0.zip
See the build instructions for your operation system below to know what to do next. Though first determine if there are any extra configuration option you may need.
Icarus Specific Configuration Options¶
Icarus takes many of the standard configuration options and those will not be described here. The following are specific to Icarus:
--enable-suffix[=suffix]
This option allows the user to build Icarus with a default suffix or when provided a user defined suffix. Older stable releases have this flag on by default e.g.(V0.8 by default will build with a “-0.8” suffix). All versions have an appropriate default suffix (“-<base_version>”).
All programs or directories are tagged with this suffix. e.g.(iverilog-0.8, vvp-0.8, etc.). The output of iverilog will reference the correct run time files and directories. The run time will check that it is running a file with a compatible version e.g.(you can not run a V0.9 file with the V0.8 run time).:
--with-valgrind
This option adds extra memory cleanup code and pool management code to allow
better memory leak checking when valgrind is available. This option is not
needed when checking for basic errors with valgrind and should not be used if
you just intend to use iverilog as a simulator.
--enable-libvvp
The vvp program is built as a small stub linked to a shared library, libvvp.so, that may be linked with other programs so that they can host a vvp simulation.
--enable-libveriuser
PLI version 1 (the ACC and TF routines) were deprecated in IEEE 1364-2005. These are supported in Icarus Verilog by the libveriuser library and cadpli module. Starting with V13, these will only be built if this option is used.
Compiling on Linux/Unix¶
Note: For a gcc compile you will need to install bison, flex, g++,
gcc and preferably bz2, zlib and readline development packages. The
bz2 and zlib development packages are required for the non-VCD waveform
dumpers and the readline development package is needed to enable better
terminal control in the vvp interactive mode.
If you are only compiling one variant then you can compile directly in the source tree. If you need multiple variants (optimized, debugging, multiple compilers) then it is recommended you compile each in their own directory.
For multiple variants create a directory for each of the variants you intend to create and in each run the following steps, adjusting the options in the configure stage to get the functionality you want. For a single build you can either build it with the source or in a separate build directory.
The following is from a Ubuntu 22.04 machine using gcc (version 11.4):
% mkdir gcc
% cd gcc
or
% cd iverilog
You can also use clang/clang++. I usual build optimized version for
normal use and reserve debugging options for a valgrind or a separate
debugging build. Make sure you have sudo permission if you are using a
system prefix area, otherwise you need to use some place you have
permission to install (e.g. ~/).:
% env CFLAGS=-O2 CXXFLAGS=-O2 LDFLAGS=-s CC=gcc CXX=g++ ../iverilog/configure --enable-suffix=-gcc --prefix=/usr/local
This will generate the following (with some inline comments):
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking for gcc... gcc
checking whether the C compiler works... yes
...
checking for gperf... gperf # required for git builds
checking for man... man # you likely want manual pages
checking for ps2pdf... ps2pdf
checking for groff... groff
checking for git... git # required for git builds
checking for flex... flex # required
checking for bison... bison # required
...
checking for tputs in -ltermcap... yes
checking for readline in -lreadline... yes
checking for add_history in -lreadline... yes
checking for readline/readline.h... yes
checking for readline/history.h... yes # you likely want this
...
checking for pthread_create in -lpthread... yes
checking for gzwrite in -lz... yes
checking for gzwrite in -lz... (cached) yes
checking for BZ2_bzdopen in -lbz2... yes
checking for BZ2_bzdopen in -lbz2... (cached) yes # you want these for fst dumping
...
<Create all the parameterized Makefile and header files>
Usually if configure fails there is some required dependency missing. I
usually review all the output to make sure it makes sense (e.g. I requested
gcc and that’s what is being used, other things match my expectation). If
all the waveform dumpers are not enabled there could be a few test failures.
Next we need to compile the code. Note: make sure you are using GNU make. It may be named gmake (e.g. GhostBSD):
% make check >& make.log
This is for a tcsh/csh shell. Bash/fish/zsh use &> instead of >&.
Once this has completed check the make.log for any errors. There should not
be any! I also check for warnings. There are often some related to the
output from bison. For example:
From: ./parse.cc
parse.cc:9462:18: warning: missing initializer for member ‘vlltype::lexical_pos’ [-Wmissing-field-initializers]
9462 | = { 1, 1, 1, 1 }
| ^
parse.cc:9462:18: warning: missing initializer for member ‘vlltype::text’ [-Wmissing-field-initializers]
and:
From: ./vvp/parse.cc
parse.cc:3242: warning: suspicious sequence in the output: m4_type [-Wother]
parse.cc:3248: warning: suspicious sequence in the output: m4_type [-Wother]
Are common, but benign warnings. Different compilers or compiler versions may have other warnings.
The expected last few lines of the make.log file and these indicate everything should be working as expected are:
...
driver/iverilog -B. -BMvpi -BPivlpp -tcheck -ocheck.vvp ../iverilog/examples/hello.vl
vvp/vvp -M- -M./vpi ./check.vvp | grep 'Hello, World'
Hello, World
If everything is good to this point and you are installing into a system
prefix; install using sudo as shown below. If you are installing into a
personal location skip the sudo:
% sudo make install
Now you should verify the regression test suite is working as expected:
% cd ../iverilog/ivtest
% ./vvp_reg.pl --suffix=-gcc
This is the original test script and should give no failures:
Running compiler/VVP tests for Icarus Verilog version: 13, suffix: -gcc.
----------------------------------------------------------------------------
macro_with_args: Passed.
mcl1: Passed.
pr622: Passed.
pr639: Passed.
...
ssetclr2: Passed.
ssetclr3: Passed.
synth_if_no_else: Passed.
ufuncsynth1: Passed.
============================================================================
Test results:
Total=3018, Passed=3013, Failed=0, Not Implemented=2, Expected Fail=3
Next run the new test script:
% ./vvp_reg.py --suffix=-gcc
This should also give no failures:
Running compiler/VVP tests for Icarus Verilog version: 13, suffix: -gcc
Using list(s): regress-vvp.list
----------------------------------------------------------------------------
always4A: Passed - CE.
always4B: Passed - CE.
analog1: Not Implemented.
analog2: Not Implemented.
...
vvp_quiet_mode: Passed.
warn_opt_sys_tf: Passed - EF.
wreal: Passed.
writemem-invalid: Passed - EF.
============================================================================
Test results: Ran 284, Failed 0.
Finally you can check that the VPI is working properly using:
% ./vpi_reg.pl --suffix=-gcc
The output for this should have no failures:
Running VPI tests for Icarus Verilog version: 13, suffix: -gcc.
----------------------------------------------------------------------------
br_gh59: Passed.
br_gh73a: Passed.
br_gh73b: Passed.
br_gh117: Passed.
...
value_change_cb2: Passed.
value_change_cb3: Passed.
value_change_cb4: Passed.
vpi_control: Passed.
============================================================================
Test results: Total=77, Passed=77, Failed=0, Not Implemented=0
You can uninstall everything using the following. If needed skip the sudo
as described in the install description above.:
% sudo make uninstall
You can cleanup the compile directory using:
% make clean
or
% make distclean
The first just cleans up just the compiled files, etc. The later cleans up
the compiled file along with all the files generated in the configure
phase.
Note that “rpm” packages of binaries for Linux are typically configured with “–prefix=/usr” per the Linux File System Standard.
Make sure you have a recent version of flex otherwise you will get an error when parsing lexor.lex.
Compiling on Macintosh OS X¶
Since Mac OS X is a BSD flavor of Unix, you can install Icarus Verilog from source using the procedure described above. You need to install the Xcode software, which includes the C and C++ compilers for Mac OS X. The package is available for free download from Apple’s developer site. Once Xcode is installed, you can build Icarus Verilog in a terminal window just like any other Unix install.
For versions newer than 10.3 the GNU Bison tool (packaged with Xcode) needs to be updated to version 3.
brew install bison
echo 'export PATH="/usr/local/opt/bison/bin:$PATH"' >> ~/.bash_profile
Icarus Verilog is also available through the Homebrew package manager: “brew install icarus-verilog”.
Cross-Compiling for Windows¶
The Cygwin and MSYS2 environments can compile Icarus Verilog as described
above for Linux/Unix. There is a MSYS2 build recipe which can be found in
the msys2/ directory. The accompanying README file provides further details.
MSYS2 is typically preferred over Cygwin since GTKWave and Icarus
Verilog are both provided as pre-compiled packages.
What follows are older instructions for building Icarus Verilog binaries for Windows using mingw cross compiler tools on Linux.
To start with, you need the mingw64-cross-* packages for your linux distribution, which gives you the x86_64-w64-mingw32-* commands installed on your system. Installing the cross environment is outside the scope of this writeup.
First, configure with this command:
$ ./configure --host=x86_64-w64-mingw32
This generates the Makefiles needed to cross compile everything with the mingw32 compiler. The configure script will generate the command name paths, so long as commands line x86_64-w64-mingw32-gcc et. al. are in your path.
Next, compile with the command:
$ make
The configure generated the cross compiler flags, but there are a few bits that need to be compiled with the native compiler. (version.exe for example is used by the build process but is not installed.) The configure script should have gotten all that right.