Cross-compiling Chrome/win

As many Chromium developers are on Linux/Mac, cross-compiling Chromium for Windows targets facilitates development for Windows targets on non-Windows machines.

It‘s possible to build most parts of the codebase on a Linux or Mac host while targeting Windows. It’s also possible to run the locally-built binaries on swarming. This document describes how to set that up, and current restrictions.


What does not work:

  • js2gtest tests are omitted from the build (bug)
  • on Mac hosts, 32-bit builds don't work (bug has more information, and this is unlikely to ever change)

All other targets build fine (including chrome, browser_tests, ...).

Uses of .asm files have been stubbed out. As a result, Crashpad cannot report crashes, and NaCl defaults to disabled and cannot be enabled in cross builds (.asm bug).

.gclient setup

  1. Tell gclient that you need Windows build dependencies by adding target_os = ['win'] to the end of your .gclient. (If you already have a target_os line in there, just add 'win' to the list.) e.g.

    solutions = [
    target_os = ['android', 'win']
  2. gclient sync, follow instructions on screen.

If you're at Google

gclient sync should automatically download the Windows SDK for you. If this fails with an error:

Please follow the instructions at

then you may need to re-authenticate via:

cd path/to/chrome/src
# Follow instructions, enter 0 as project id.
download_from_google_storage --config

gclient sync should now succeed. Skip ahead to the GN setup section.

If you're not at Google

After installing Microsoft's development tools, you can package your Windows SDK installation into a zip file by running the following on a Windows machine:

cd path/to/depot_tools/win_toolchain
python <vs version> -w <win version>

where <vs version> and <win version> correspond respectively to the versions of Visual Studio (e.g. 2019) and of the Windows SDK (e.g. 10.0.19041.0) installed on the Windows machine. Note that if you didn't install the ARM64 components of the SDK as noted in the link above, you should add --noarm to the parameter list.

These commands create a zip file named <hash value>.zip. Then, to use the generated file in a Linux or Mac host, the following environment variables need to be set:

export GYP_MSVS_HASH_<toolchain hash>=<hash value>

<base url> is the path of the directory containing the zip file (note that specifying scheme file:// is not required).

<toolchain hash> is hardcoded in src/build/ and can be found by setting DEPOT_TOOLS_WIN_TOOLCHAIN_BASE_URL and running gclient sync:

gclient sync
Running hooks:  17% (11/64) win_toolchain
________ running '/usr/bin/python src/build/ update --force' in <chromium dir>
Windows toolchain out of date or doesn't exist, updating (Pro)...
desired_hash: <toolchain hash>

GN setup


target_os = "win"

to your

If you're building on an arm host (e.g. a Mac with an Apple Silicon chip), you very likely also want to add

target_cpu = "x64"

lest you build an arm64 chrome/win binary.

Then just build, e.g.

ninja -C out/gnwin base_unittests.exe


This should be supported by the default (Goma RBE) backend.

Copying and running chrome

A convenient way to copy chrome over to a Windows box is to build the mini_installer target. Then, copy just mini_installer.exe over to the Windows box and run it to install the chrome you just built.

Note that the mini_installer doesn't include PDB files. PDB files are needed to correctly symbolize stack traces (or if you want to attach a debugger).

Running tests on swarming

You can run the Windows binaries you built on swarming, like so:

tools/ out/gnwin base_unittests -- [ --gtest_filter=... ]

See the contents of for how to do this manually.

The linux-win_cross-rel buildbot does 64-bit release cross builds, and also runs tests. You can look at it to get an idea of which tests pass in the cross build.