= Verilator Installation
:toc: right

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== Introduction

This discusses how to install Verilator.  For more general information
please see https://verilator.org[verilator.org].

== Quick-start

=== Install From a Package Manager

Using a distribution's package manager is the easiest way to get
started. (Note packages are unlikely to have the most recent version, so
Git, below, maybe a better alternative.) To install as a package:

   apt-get install verilator

If this works, skip down to <<Running Verilator>>.

=== Docker

Verilator is available in pre-built Docker containers. See
https://github.com/verilator/verilator/blob/master/ci/docker/run/README.adoc

=== Git

Installing Verilator with Git provides the most flexibility.
For additional options and details see the additional sections below.  In
brief:

// Also update README
....
# Prerequisites:
#sudo apt-get install git make autoconf g++ flex bison
#sudo apt-get install libfl2  # Ubuntu only (ignore if gives error)
#sudo apt-get install libfl-dev  # Ubuntu only (ignore if gives error)

git clone https://git.veripool.org/git/verilator   # Only first time
## Note the URL above is not a page you can see with a browser, it's for git only

# Every time you need to build:
unsetenv VERILATOR_ROOT  # For csh; ignore error if on bash
unset VERILATOR_ROOT  # For bash
cd verilator
git pull        # Make sure git repository is up-to-date
git tag         # See what versions exist
#git checkout master      # Use development branch (e.g. recent bug fixes)
#git checkout stable      # Use most recent stable release
#git checkout v{version}  # Switch to specified release version

autoconf        # Create ./configure script
./configure
make
sudo make install
# Now see "man verilator" or online verilator.pdf's for the example tutorials
....

If this works, skip down to <<Running Verilator>>.

== Detailed Build Instructions

This section describes details of the build process, and assumes you are
building from Git or a tarball.  For using a pre-built binary for your
Linux distribution, see instead <<Install From a Package Manager>>.

=== OS Requirements

Verilator is developed and has primary testing on Ubuntu.  Versions have
also built on Redhat Linux, Apple OS-X, HPUX and Solaris.  It should run
with minor porting on any GNU/Linux-ish platform.  Verilator also works on
Windows under Cygwin, and Windows under MinGW (gcc -mno-cygwin).  Verilated
output (not Verilator itself) compiles under all the options above, plus
MSVC++.

=== Install Prerequisites

To build Verilator you will need to install some standard packages:

   sudo apt-get install git
   sudo apt-get install autoconf
   sudo apt-get install flex bison

The following are optional, but improve compilation speed:

   sudo apt-get install libgoogle-perftools-dev

Additionally, to build or run Verilator you need these standard packages:

   sudo apt-get install perl python3
   sudo apt-get install make
   sudo apt-get install g++  # Alternatively, clang
   sudo apt-get install libgz  # Non-Ubuntu (ignore if gives error)
   sudo apt-get install libfl2 libfl-dev zlibc zlib1g zlib1g-dev  # Ubuntu only (ignore if gives error)

Those developing Verilator may also want these (see internals.adoc):

   sudo apt-get install gdb asciidoctor graphviz
   cpan install Pod::Perldoc
   cpan install Unix::Processors

==== Install SystemC

If you will be using SystemC (vs straight C++ output), download
https://www.accellera.org/downloads/standards/systemc[SystemC].
Follow their installation instructions.  You will need to set `SYSTEMC_INCLUDE`
to point to the include directory with `systemc.h` in it, and `SYSTEMC_LIBDIR`
to points to the directory with `libsystemc.a` in it.  (Older installations
may set `SYSTEMC` and `SYSTEMC_ARCH` instead.)

==== Install GTKWave

To make use of Verilator FST tracing you will want
http://gtkwave.sourceforge.net/[GTKwave] installed, however this is not
required at Verilator build time.

=== Obtain Sources

You may use Git or a tarball for the sources.  Git is the supported option.
(If using a historical build that uses a tarball, tarballs are obtained
from https://www.veripool.org/projects/verilator/wiki/Download[Verilator
Downloads]; we presume you know how to use it, and is not described here.)

Get the sources from the repository: (You need do this only once, ever.)

   git clone https://git.veripool.org/git/verilator   # Only first time
   ## Note the URL above is not a page you can see with a browser, it's for git only

Enter the checkout and determine what version/branch to use:

   cd verilator
   git pull        # Make sure we're up-to-date
   git tag         # See what versions exist
   #git checkout master      # Use development branch (e.g. recent bug fix)
   #git checkout stable      # Use most recent release
   #git checkout v{version}  # Switch to specified release version

=== Auto Configure

Create the configuration script:

   autoconf        # Create ./configure script

=== Eventual Installation Options

Before configuring the build, you have to decide how you're going to
eventually install the kit.  Verilator will be compiling the current value
of `VERILATOR_ROOT`, `SYSTEMC_INCLUDE`, and `SYSTEMC_LIBDIR` as defaults
into the executable, so they must be correct before configuring.

These are the options:

==== 1. Run-in-Place from VERILATOR_ROOT

Our personal favorite is to always run Verilator in-place from its Git
directory.  This allows the easiest experimentation and upgrading, and
allows many versions of Verilator to co-exist on a system.

   export VERILATOR_ROOT=`pwd`   # if your shell is bash
   setenv VERILATOR_ROOT `pwd`   # if your shell is csh
   ./configure
   # Running will use files from $VERILATOR_ROOT, so no install needed

Note after installing (below steps), a calling program or shell must set
the environment variable `VERILATOR_ROOT` to point to this Git directory,
then execute `$VERILATOR_ROOT/bin/verilator`, which will find the path to
all needed files.

==== 2. Install into a CAD Disk

You may eventually be installing onto a project/company-wide "CAD" tools
disk that may support multiple versions of every tool.  Target the build to
a destination directory name that includes the Verilator version name:

   unset VERILATOR_ROOT      # if your shell is bash
   unsetenv VERILATOR_ROOT   # if your shell is csh
   # For the tarball, use the version number instead of git describe
   ./configure --prefix /CAD_DISK/verilator/`git describe | sed "s/verilator_//"`

Note after installing (below steps), if you use
http://modules.sourceforge.net/[modulecmd], you'll want a module file like
the following:

.modulecmd's verilator/version file
----
set install_root /CAD_DISK/verilator/{version-number-used-above}
unsetenv VERILATOR_ROOT
prepend-path PATH $install_root/bin
prepend-path MANPATH $install_root/man
prepend-path PKG_CONFIG_PATH $install_root/share/pkgconfig
----

==== 3. Install into a Specific Path

You may eventually install Verilator into a specific installation prefix,
as most GNU tools support:

   unset VERILATOR_ROOT      # if your shell is bash
   unsetenv VERILATOR_ROOT   # if your shell is csh
   ./configure --prefix /opt/verilator-VERSION

Then after installing (below steps) you will need to add
`/opt/verilator-VERSION/bin` to `$PATH`.

==== 4. Install System Globally

The final option is to eventually install Verilator globally, using the
normal system paths:

   unset VERILATOR_ROOT      # if your shell is bash
   unsetenv VERILATOR_ROOT   # if your shell is csh
   ./configure

Then after installing (below) the binary directories should already be in
your `$PATH`.

=== Configure

The command to configure the package was described in the previous step.
Developers should configure to have more complete developer tests.
Additional packages may be required for these tests.

   export VERILATOR_AUTHOR_SITE=1    # Put in your .bashrc
   ./configure --enable-longtests  ...above options...

=== Compile

Compile Verilator:

   make -j

=== Test

Check the compilation by running self-tests:

   make test

=== Install

If you used any but the <<1. Run-in-Place from VERILATOR_ROOT>> scheme,
install to the OS-standard place:

   make install

== Running Verilator

To run Verilator, see the example sections in the
https://verilator.org/verilator_doc.html[Verilator manual (HTML)],
or https://verilator.org/verilator_doc.pdf[Verilator manual (PDF)].

Also see the `examples/` directory that is part of the kit, and is installed
(in a OS-specific place, often in e.g. `/usr/local/share/verilator/examples`).

     cd examples/make_hello_c
     make

Note if you did a `make install` above you should not have `VERILATOR_ROOT`
set in your environment; it is built into the executable.

== Announcements

To get notified of new releases, login to
https://www.veripool.org[Veripool], and click the "watch" button near the
top right under https://www.veripool.org/projects/verilator/news[Verilator
News].

== Directory Structure

Some relevant files and directories in this package are as follows:

   Changes                     => Version history
   README.adoc                 => This document
   bin/verilator               => Compiler wrapper invoked to Verilate code
   docs/                       => Additional documentation
   examples/make_hello_c       => Example GNU-make simple Verilog->C++ conversion
   examples/make_hello_sc      => Example GNU-make simple Verilog->SystemC conversion
   examples/make_tracing_c     => Example GNU-make Verilog->C++ with tracing
   examples/make_tracing_sc    => Example GNU-make Verilog->SystemC with tracing
   examples/make_protect_lib   => Example using --protect-lib
   examples/cmake_hello_c      => Example building make_hello_c with CMake
   examples/cmake_hello_sc     => Example building make_hello_sc with CMake
   examples/cmake_tracing_c    => Example building make_tracing_c with CMake
   examples/cmake_tracing_sc   => Example building make_tracing_sc with CMake
   examples/cmake_protect_lib  => Example building make_protect_lib with CMake
   include/                    => Files that should be in your -I compiler path
   include/verilated*.cpp      => Global routines to link into your simulator
   include/verilated*.h        => Global headers
   include/verilated.mk        => Common Makefile
   src/                        => Translator source code
   test_regress                => Internal tests

For files created after a design is Verilated, see the
https://verilator.org/verilator_doc.html[Verilator manual (HTML)],
or https://verilator.org/verilator_doc.pdf[Verilator manual (PDF)].

== License

Copyright 2008-2020 by Wilson Snyder.  Verilator is free software; you can
redistribute it and/or modify it under the terms of either the GNU Lesser
General Public License Version 3 or the Perl Artistic License Version 2.0.
