Checking out and building Chromium on Linux

There are instructions for other platforms linked from the get the code page.

Instructions for Google Employees

Are you a Google employee? See go/building-chrome instead.

[TOC]

System requirements

An x86-64 machine with at least 8GB of RAM. More than 16GB is highly recommended. If your machine has an SSD, it is recommended to have >=32GB/>=16GB of swap for machines with 8GB/16GB of RAM respectively.
At least 100GB of free disk space. It does not have to be on the same drive; Allocate ~50-80GB on HDD for build.
You must have Git and Python v3.8+ installed already (and python3 must point to a Python v3.8+ binary). Depot_tools bundles an appropriate version of Python in $depot_tools/python-bin, if you don't have an appropriate version already on your system.

Most development is done on Ubuntu (Chromium's build infrastructure currently runs 22.04, Jammy Jellyfish). There are some instructions for other distros below, but they are mostly unsupported, but installation instructions can be found in Docker.

Install `depot_tools`

Clone the depot_tools repository:

$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git

Add depot_tools to the beginning of your PATH (you will probably want to put this in your ~/.bashrc or ~/.zshrc). Assuming you cloned depot_tools to /path/to/depot_tools:

$ export PATH="/path/to/depot_tools:$PATH"

When cloning depot_tools to your home directory do not use ~ on PATH, otherwise gclient runhooks will fail to run. Rather, you should use either $HOME or the absolute path:

$ export PATH="${HOME}/depot_tools:$PATH"

Get the code

Create a chromium directory for the checkout and change to it (you can call this whatever you like and put it wherever you like, as long as the full path has no spaces):

$ mkdir ~/chromium && cd ~/chromium

Run the fetch tool from depot_tools to check out the code and its dependencies.

$ fetch --nohooks chromium

*** note NixOS users: tools like fetch won’t work without a Nix shell. Clone the tools repo with git, then run nix-shell tools/nix/shell.nix.

If you don't want the full repo history, you can save a lot of time by adding the --no-history flag to fetch.

Expect the command to take 30 minutes on even a fast connection, and many hours on slower ones.

If you've already installed the build dependencies on the machine (from another checkout, for example), you can omit the --nohooks flag and fetch will automatically execute gclient runhooks at the end.

When fetch completes, it will have created a hidden .gclient file and a directory called src in the working directory. The remaining instructions assume you have switched to the src directory:

$ cd src

Install additional build dependencies

Once you have checked out the code, and assuming you're using Ubuntu, run build/install-build-deps.sh

$ ./build/install-build-deps.sh

You may need to adjust the build dependencies for other distros. There are some notes at the end of this document, but we make no guarantees for their accuracy.

Run the hooks

Once you've run install-build-deps at least once, you can now run the Chromium-specific hooks, which will download additional binaries and other things you might need:

$ gclient runhooks

Optional: You can also install API keys if you want your build to talk to some Google services, but this is not necessary for most development and testing purposes.

Setting up the build

Chromium uses Ninja as its main build tool along with a tool called GN to generate .ninja files. You can create any number of build directories with different configurations. To create a build directory, run:

$ gn gen out/Default

You only have to run this once for each new build directory, Ninja will update the build files as needed.
You can replace Default with another name, but it should be a subdirectory of out.
For other build arguments, including release settings, see GN build configuration. The default will be a debug component build matching the current host operating system and CPU.
For more info on GN, run gn help on the command line or read the quick start guide.

Faster builds

This section contains some things you can change to speed up your builds, sorted so that the things that make the biggest difference are first.

Use Reclient

*** note Warning: If you are a Google employee, do not follow the instructions below. See go/chrome-linux-build#setup-remote-execution instead.

Chromium's build can be sped up significantly by using a remote execution system compatible with REAPI. This allows you to benefit from remote caching and executing many build actions in parallel on a shared cluster of workers.

For contributors who have tryjob access , please ask a Googler to email accounts@chromium.org on your behalf to access RBE backend paid by Google. Note that reclient for external contributors is a best-effort process. We do not guarantee when you will be invited. Reach out to reclient-users@chromium.org if you have any questions about reclient usage.

To get started, you need access to an REAPI-compatible backend. The following instructions assume that you received an invitation from Google to use Chromium's RBE service and were granted access to it. However, you are welcome to use any of the other compatible backends, in which case you will have to adapt the following instructions regarding the authentication method, instance name, etc. to work with your backend.

Chromium's build uses a client developed by Google called reclient to remotely execute build actions. If you would like to use reclient with RBE, you'll first need to:

Install the gcloud CLI. You can pick any installation method from that page that works best for you.
Run gcloud auth login --update-adc and login with your authorized account. Ignore the message about the --update-adc flag being deprecated.

Next, you'll have to specify your rbe_instance in your .gclient configuration to use the correct one for Chromium contributors:

*** note Warning: If you are a Google employee, do not follow the instructions below. See go/chrome-linux-build#setup-remote-execution instead.

solutions = [
  {
    ...,
    "custom_vars": {
      # This is the correct instance name for using Chromium's RBE service.
      # You can only use it if you were granted access to it. If you use your
      # own REAPI-compatible backend, you will need to change this accordingly
      # to its requirements.
      "rbe_instance": "projects/rbe-chromium-untrusted/instances/default_instance",
    },
  },
]

And run gclient sync. This will regenerate the config files in buildtools/reclient_cfgs to use the rbe_instance that you just added to your .gclient file.

Then, add the following GN args to your args.gn:

use_remoteexec = true
reclient_cfg_dir = "../../buildtools/reclient_cfgs/linux"

*** note If you are building an older version of Chrome with reclient you will need to use rbe_cfg_dir = "../../buildtools/reclient_cfgs_linux"

That's it. Remember to always use autoninja for building Chromium as described below, which handles the startup and shutdown of the reproxy daemon process that's required during the build, instead of directly invoking ninja.

Disable NaCl

By default, the build includes support for Native Client (NaCl), but most of the time you won't need it. You can set the GN argument enable_nacl=false and it won't be built.

Include fewer debug symbols

By default GN produces a build with all of the debug assertions enabled (is_debug=true) and including full debug info (symbol_level=2). Setting symbol_level=1 will produce enough information for stack traces, but not line-by-line debugging. Setting symbol_level=0 will include no debug symbols at all. Either will speed up the build compared to full symbols.

Disable debug symbols for Blink and v8

Due to its extensive use of templates, the Blink code produces about half of our debug symbols. If you don't ever need to debug Blink, you can set the GN arg blink_symbol_level=0. Similarly, if you don't need to debug v8 you can improve build speeds by setting the GN arg v8_symbol_level=0.

Use Icecc

Icecc is the distributed compiler with a central scheduler to share build load. Currently, many external contributors use it. e.g. Intel, Opera, Samsung (this is not useful if you're using Reclient).

In order to use icecc, set the following GN args:

use_debug_fission=false
is_clang=false

See these links for more on the bundled_binutils limitation, the debug fission limitation.

Using the system linker may also be necessary when using glibc 2.21 or newer. See related bug.

ccache

You can use ccache to speed up local builds (again, this is not useful if you're using Reclient).

Increase your ccache hit rate by setting CCACHE_BASEDIR to a parent directory that the working directories all have in common (e.g., /home/yourusername/development). Consider using CCACHE_SLOPPINESS=include_file_mtime (since if you are using multiple working directories, header times in svn sync'ed portions of your trees will be different - see the ccache troubleshooting section for additional information). If you use symbolic links from your home directory to get to the local physical disk directory where you keep those working development directories, consider putting

alias cd="cd -P"

in your .bashrc so that $PWD or cwd always refers to a physical, not logical directory (and make sure CCACHE_BASEDIR also refers to a physical parent).

If you tune ccache correctly, a second working directory that uses a branch tracking trunk and is up to date with trunk and was gclient sync'ed at about the same time should build chrome in about 1/3 the time, and the cache misses as reported by ccache -s should barely increase.

This is especially useful if you use git-worktree and keep multiple local working directories going at once.

Using tmpfs

You can use tmpfs for the build output to reduce the amount of disk writes required. I.e. mount tmpfs to the output directory where the build output goes:

As root:

mount -t tmpfs -o size=20G,nr_inodes=40k,mode=1777 tmpfs /path/to/out

*** note Caveat: You need to have enough RAM + swap to back the tmpfs. For a full debug build, you will need about 20 GB. Less for just building the chrome target or for a release build.

Quick and dirty benchmark numbers on a HP Z600 (Intel core i7, 16 cores hyperthreaded, 12 GB RAM)

With tmpfs:
- 12m:20s
Without tmpfs
- 15m:40s

Smaller builds

The Chrome binary contains embedded symbols by default. You can reduce its size by using the Linux strip command to remove this debug information. You can also reduce binary size and turn on all optimizations by enabling official build mode, with the GN arg is_official_build = true.

Build Chromium

Build Chromium (the "chrome" target) with Ninja using the command:

$ autoninja -C out/Default chrome

(autoninja is a wrapper that automatically provides optimal values for the arguments passed to ninja.)

You can get a list of all of the other build targets from GN by running gn ls out/Default from the command line. To compile one, pass the GN label to Ninja with no preceding "//" (so, for //chrome/test:unit_tests use autoninja -C out/Default chrome/test:unit_tests).

Compile a single file

Ninja supports a special syntax ^ to compile a single object file specyfing the source file. For example, autoninja -C out/Default ../../base/logging.cc^ compiles obj/base/base/logging.o.

In addition to foo.cc^, Siso also supports foo.h^ syntax to compile the corresponding foo.o if it exists.

Run Chromium

Once it is built, you can simply run the browser:

$ out/Default/chrome

If you're using a remote machine that supports Chrome Remote Desktop, you can add this to your .bashrc / .bash_profile.

if [[ -z "${DISPLAY}" ]]; then
  # In reality, Chrome Remote Desktop starts with 20 and increases until it
  # finds an available ID [1]. So this isn't guaranteed to always work, but
  # should work on the vast majoriy of cases.
  #
  # [1] https://source.chromium.org/chromium/chromium/src/+/main:remoting/host/linux/linux_me2me_host.py;l=112;drc=464a632e21bcec76c743930d4db8556613e21fd8
  export DISPLAY=:20
fi

This means if you launch Chrome from an SSH session, the UI output will be available in Chrome Remote Desktop.

Running test targets

Tests are split into multiple test targets based on their type and where they exist in the directory structure. To see what target a given unit test or browser test file corresponds to, the following command can be used:

$ gn refs out/Default --testonly=true --type=executable --all chrome/browser/ui/browser_list_unittest.cc
//chrome/test:unit_tests

In the example above, the target is unit_tests. The unit_tests binary can be built by running the following command:

$ autoninja -C out/Default unit_tests

You can run the tests by running the unit_tests binary. You can also limit which tests are run using the --gtest_filter arg, e.g.:

$ out/Default/unit_tests --gtest_filter="BrowserListUnitTest.*"

You can find out more about GoogleTest at its GitHub page.

Update your checkout

To update an existing checkout, you can run

$ git rebase-update
$ gclient sync

The first command updates the primary Chromium source repository and rebases any of your local branches on top of tip-of-tree (aka the Git branch origin/main). If you don't want to use this script, you can also just use git pull or other common Git commands to update the repo.

The second command syncs dependencies to the appropriate versions and re-runs hooks as needed.

Tips, tricks, and troubleshooting

Linker Crashes

If, during the final link stage:

LINK out/Debug/chrome

You get an error like:

collect2: ld terminated with signal 6 Aborted terminate called after throwing an instance of 'std::bad_alloc'
collect2: ld terminated with signal 11 [Segmentation fault], core dumped

or:

LLVM ERROR: out of memory

you are probably running out of memory when linking. You must use a 64-bit system to build. Try the following build settings (see GN build configuration for other settings):

Build in release mode (debugging symbols require more memory): is_debug = false
Turn off symbols: symbol_level = 0
Build in component mode (this is for development only, it will be slower and may have broken functionality): is_component_build = true
For official (ThinLTO) builds on Linux, increase the vm.max_map_count kernel parameter: increase the vm.max_map_count value from default (like 65530) to for example 262144. You can run the sudo sysctl -w vm.max_map_count=262144 command to set it in the current session from the shell, or add the vm.max_map_count=262144 to /etc/sysctl.conf to save it permanently.

Next Steps

If you want to contribute to the effort toward a Chromium-based browser for Linux, please check out the Linux Development page for more information.

Notes for other distros

Arch Linux

Instead of running install-build-deps.sh to install build dependencies, run:

$ sudo pacman -S --needed python perl gcc gcc-libs bison flex gperf pkgconfig \
nss alsa-lib glib2 gtk3 nspr freetype2 cairo dbus xorg-server-xvfb \
xorg-xdpyinfo

For the optional packages on Arch Linux:

php-cgi is provided with pacman
wdiff is not in the main repository but dwdiff is. You can get wdiff in AUR/yaourt

Crostini (Debian based)

First install the file and lsb-release commands for the script to run properly:

$ sudo apt-get install file lsb-release

Then invoke install-build-deps.sh with the --no-arm argument, because the ARM toolchain doesn't exist for this configuration:

$ sudo install-build-deps.sh --no-arm

Fedora

Instead of running build/install-build-deps.sh, run:

su -c 'yum install git python bzip2 tar pkgconfig atk-devel alsa-lib-devel \
bison binutils brlapi-devel bluez-libs-devel bzip2-devel cairo-devel \
cups-devel dbus-devel dbus-glib-devel expat-devel fontconfig-devel \
freetype-devel gcc-c++ glib2-devel glibc.i686 gperf glib2-devel \
gtk3-devel java-1.*.0-openjdk-devel libatomic libcap-devel libffi-devel \
libgcc.i686 libjpeg-devel libstdc++.i686 libX11-devel libXScrnSaver-devel \
libXtst-devel libxkbcommon-x11-devel ncurses-compat-libs nspr-devel nss-devel \
pam-devel pango-devel pciutils-devel pulseaudio-libs-devel zlib.i686 httpd \
mod_ssl php php-cli python-psutil wdiff xorg-x11-server-Xvfb'

The fonts needed by Blink's web tests can be obtained by following these instructions. For the optional packages:

php-cgi is provided by the php-cli package.
sun-java6-fonts is covered by the instructions linked above.

Gentoo

You can just run emerge www-client/chromium.

NixOS

To get a shell with the dev environment:

$ nix-shell tools/nix/shell.nix

To run a command in the dev environment:

$ NIX_SHELL_RUN='autoninja -C out/Default chrome' nix-shell tools/nix/shell.nix

To set up clangd with remote indexing support, run the command below, then copy the path into your editor config:

$ NIX_SHELL_RUN='readlink /usr/bin/clangd' nix-shell tools/nix/shell.nix

OpenSUSE

Use zypper command to install dependencies:

(openSUSE 11.1 and higher)

sudo zypper in subversion pkg-config python perl bison flex gperf \
     mozilla-nss-devel glib2-devel gtk-devel wdiff lighttpd gcc gcc-c++ \
     mozilla-nspr mozilla-nspr-devel php5-fastcgi alsa-devel libexpat-devel \
     libjpeg-devel libbz2-devel

For 11.0, use libnspr4-0d and libnspr4-dev instead of mozilla-nspr and mozilla-nspr-devel, and use php5-cgi instead of php5-fastcgi.

(openSUSE 11.0)

sudo zypper in subversion pkg-config python perl \
     bison flex gperf mozilla-nss-devel glib2-devel gtk-devel \
     libnspr4-0d libnspr4-dev wdiff lighttpd gcc gcc-c++ libexpat-devel \
     php5-cgi alsa-devel gtk3-devel jpeg-devel

The Ubuntu package sun-java6-fonts contains a subset of Java of the fonts used. Since this package requires Java as a prerequisite anyway, we can do the same thing by just installing the equivalent openSUSE Sun Java package:

sudo zypper in java-1_6_0-sun

WebKit is currently hard-linked to the Microsoft fonts. To install these using zypper

sudo zypper in fetchmsttfonts pullin-msttf-fonts

To make the fonts installed above work, as the paths are hardcoded for Ubuntu, create symlinks to the appropriate locations:

sudo mkdir -p /usr/share/fonts/truetype/msttcorefonts
sudo ln -s /usr/share/fonts/truetype/arial.ttf /usr/share/fonts/truetype/msttcorefonts/Arial.ttf
sudo ln -s /usr/share/fonts/truetype/arialbd.ttf /usr/share/fonts/truetype/msttcorefonts/Arial_Bold.ttf
sudo ln -s /usr/share/fonts/truetype/arialbi.ttf /usr/share/fonts/truetype/msttcorefonts/Arial_Bold_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/ariali.ttf /usr/share/fonts/truetype/msttcorefonts/Arial_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/comic.ttf /usr/share/fonts/truetype/msttcorefonts/Comic_Sans_MS.ttf
sudo ln -s /usr/share/fonts/truetype/comicbd.ttf /usr/share/fonts/truetype/msttcorefonts/Comic_Sans_MS_Bold.ttf
sudo ln -s /usr/share/fonts/truetype/cour.ttf /usr/share/fonts/truetype/msttcorefonts/Courier_New.ttf
sudo ln -s /usr/share/fonts/truetype/courbd.ttf /usr/share/fonts/truetype/msttcorefonts/Courier_New_Bold.ttf
sudo ln -s /usr/share/fonts/truetype/courbi.ttf /usr/share/fonts/truetype/msttcorefonts/Courier_New_Bold_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/couri.ttf /usr/share/fonts/truetype/msttcorefonts/Courier_New_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/impact.ttf /usr/share/fonts/truetype/msttcorefonts/Impact.ttf
sudo ln -s /usr/share/fonts/truetype/times.ttf /usr/share/fonts/truetype/msttcorefonts/Times_New_Roman.ttf
sudo ln -s /usr/share/fonts/truetype/timesbd.ttf /usr/share/fonts/truetype/msttcorefonts/Times_New_Roman_Bold.ttf
sudo ln -s /usr/share/fonts/truetype/timesbi.ttf /usr/share/fonts/truetype/msttcorefonts/Times_New_Roman_Bold_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/timesi.ttf /usr/share/fonts/truetype/msttcorefonts/Times_New_Roman_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/verdana.ttf /usr/share/fonts/truetype/msttcorefonts/Verdana.ttf
sudo ln -s /usr/share/fonts/truetype/verdanab.ttf /usr/share/fonts/truetype/msttcorefonts/Verdana_Bold.ttf
sudo ln -s /usr/share/fonts/truetype/verdanai.ttf /usr/share/fonts/truetype/msttcorefonts/Verdana_Italic.ttf
sudo ln -s /usr/share/fonts/truetype/verdanaz.ttf /usr/share/fonts/truetype/msttcorefonts/Verdana_Bold_Italic.ttf