# Checking out and building Chromium on Linux There are instructions for other platforms linked from the [get the code](../get_the_code.md) page. ## Instructions for Google Employees Are you a Google employee? See [go/building-chrome](https://goto.google.com/building-chrome) instead. [TOC] ## System requirements * A 64-bit Intel machine with at least 8GB of RAM. More than 16GB is highly recommended. * At least 100GB of free disk space. * You must have Git and Python v3.6+ installed already (and `python3` must point to a Python v3.6+ binary). Most development is done on Ubuntu (currently 18.04, Bionic Beaver). There are some instructions for other distros below, but they are mostly unsupported. ## Install `depot_tools` Clone the `depot_tools` repository: ```shell $ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git ``` Add `depot_tools` to the end 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`: ```shell $ export PATH="$PATH:/path/to/depot_tools" ``` When cloning `depot_tools` to your home directory **do not** use `~` on PATH, otherwise `gclient runhooks` will fail to run. Rather, you should use either `$HOME` or the absolute path: ```shell $ export PATH="$PATH:${HOME}/depot_tools" ``` ## 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): ```shell $ mkdir ~/chromium && cd ~/chromium ``` Run the `fetch` tool from depot_tools to check out the code and its dependencies. ```shell $ fetch --nohooks chromium ``` 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: ```shell $ 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) ```shell $ ./build/install-build-deps.sh ``` You may need to adjust the build dependencies for other distros. There are some [notes](#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: ```shell $ gclient runhooks ``` *Optional*: You can also [install API keys](https://www.chromium.org/developers/how-tos/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](https://ninja-build.org) as its main build tool along with a tool called [GN](https://gn.googlesource.com/gn/+/main/docs/quick_start.md) to generate `.ninja` files. You can create any number of *build directories* with different configurations. To create a build directory, run: ```shell $ 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](https://www.chromium.org/developers/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](https://gn.googlesource.com/gn/+/main/docs/quick_start.md). ### 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 Goma Google developed the distributed compiler called [Goma](https://chromium.googlesource.com/infra/goma/client). If you would like to use `Goma` provisioned by Google, please follow [Goma for Chromium contributors](https://chromium.googlesource.com/infra/goma/client/+/HEAD/doc/early-access-guide.md). If you are a Google employee, see [go/building-chrome](https://goto.google.com/building-chrome) instead. #### Disable NaCl By default, the build includes support for [Native Client (NaCl)](https://developer.chrome.com/native-client), 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](https://github.com/icecc/icecream) 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 Goma). 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](https://github.com/icecc/icecream/commit/b2ce5b9cc4bd1900f55c3684214e409fa81e7a92), the [debug fission limitation](http://gcc.gnu.org/wiki/DebugFission). Using the system linker may also be necessary when using glibc 2.21 or newer. See [related bug](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=808181). #### ccache You can use [ccache](https://ccache.dev) to speed up local builds (again, this is not useful if you're using Goma). 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](https://ccache.dev/manual/latest.html#_troubleshooting) 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](http://git-scm.com/docs/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 by disabling debug mode, disabling dchecks, and turning on all optimizations by enabling official build mode, with these GN args: ``` is_debug = false dcheck_always_on = false is_official_build = true ``` ## Build Chromium Build Chromium (the "chrome" target) with Ninja using the command: ```shell $ 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`). ## Run Chromium Once it is built, you can simply run the browser: ```shell $ out/Default/chrome ``` ## Running test targets First build the unit_tests binary by running the command: ```shell $ 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.: ```shell $ out/Default/unit_tests --gtest_filter="PushClientTest.*" ``` You can find out more about GoogleTest at its [GitHub page](https://github.com/google/googletest). ## Update your checkout To update an existing checkout, you can run ```shell $ 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 ``` 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](https://www.chromium.org/developers/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` ### More links * Information about [building with Clang](../clang.md). * You may want to [use a chroot](using_a_chroot.md) to isolate yourself from versioning or packaging conflicts. * Cross-compiling for ARM? See [LinuxChromiumArm](chromium_arm.md). * Want to use Eclipse as your IDE? See [LinuxEclipseDev](eclipse_dev.md). * Want to use your built version as your default browser? See [LinuxDevBuildAsDefaultBrowser](dev_build_as_default_browser.md). ## Next Steps If you want to contribute to the effort toward a Chromium-based browser for Linux, please check out the [Linux Development page](development.md) for more information. ## Notes for other distros ### Arch Linux Instead of running `install-build-deps.sh` to install build dependencies, run: ```shell $ sudo pacman -S --needed python perl gcc gcc-libs bison flex gperf pkgconfig \ nss alsa-lib glib2 gtk3 nspr freetype2 cairo dbus libgnome-keyring \ 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: ```shell $ 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: ```shell $ sudo install-build-deps.sh --no-arm ``` ### Fedora Instead of running `build/install-build-deps.sh`, run: ```shell 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 libgnome-keyring-devel 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](https://gist.github.com/pwnall/32a3b11c2b10f6ae5c6a6de66c1e12ae). 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`. ### OpenSUSE Use `zypper` command to install dependencies: (openSUSE 11.1 and higher) ```shell 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) ```shell 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: ```shell sudo zypper in java-1_6_0-sun ``` WebKit is currently hard-linked to the Microsoft fonts. To install these using `zypper` ```shell 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: ```shell 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 ``` 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: ```shell sudo zypper in java-1_6_0-sun ``` WebKit is currently hard-linked to the Microsoft fonts. To install these using `zypper` ```shell 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: ```shell 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 ``` And then for the Java fonts: ```shell sudo mkdir -p /usr/share/fonts/truetype/ttf-lucida sudo find /usr/lib*/jvm/java-1.6.*-sun-*/jre/lib -iname '*.ttf' -print \ -exec ln -s {} /usr/share/fonts/truetype/ttf-lucida \; ```