Apple is planning on selling Macs with arm chips by the end of 2020. This document describes the state of native binaries for these Macs.
There's a bot that builds for arm. It cross-builds on an Intel machine.
There's also a tester bot that continuously runs tests. Most tests pass.
You can build Chrome for arm macs on an Intel Mac. To build for arm64, you have to do 2 things:
use the MacOSX11.0.sdk that comes with Xcode 12.2. If you‘re on Google’s corporate network, this SDK is part of the hermetic toolchain and will be used automatically. Otherwise, manually download and install this version of Xcode and, if necessary, make it the active Xcode with xcode-select.
Add target_cpu = "arm64" to your args.gn.
Then build normally.
To run a built Chromium, you need to copy it to your arm mac. If you don‘t do a component build (e.g. a regular is_debug=false build), you can just copy over Chromium.app from your build directory. If you copy it using macOS’s “Shared Folder” feature and Finder, Chromium.app should be directly runnable. If you zip, upload Chromium.app to some web service and download it on the DTK, browsers will set the com.apple.quarantine bit, which will cause Finder to say "Chromium" is damanged and can't be opened. You should move it to the Trash.". In Console.app, the kernel will log kernel: Security policy would not allow process: 2204, /Users/you/Downloads/Chromium.app/Contents/MacOS/Chromium and amfid will log amfid: /Users/you/Downloads/Chromium.app/Contents/MacOS/Chromium signature not valid: -67050. To fix this, open a terminal and run
% cd ~/Downloads && xattr -rc Chromium.app
After that, it should start fine.
As an alternative to building locally, changes can be submitted to the opt-in mac-arm64-rel trybot. A small number of swarming bots are also available for Googlers to run tests on.
You can follow the Mac-ARM64 label to get updates on progress.
A “universal” (or “fat”) .app can be created from distinct x86_64 and arm64 builds produced from the same source version. Chromium has a universalizer.py tool that can then be used to merge the two builds into a single universal .app.
% ninja -C out/release_x86_64 chrome
% ninja -C out/release_arm64 chrome
% mkdir out/release_universal
% chrome/installer/mac/universalizer.py \
out/release_x86_64/Chromium.app \
out/release_arm64/Chromium.app \
out/release_universal/Chromium.app
The universal build is produced in this way rather than having a single all-encompassing gn configuration because:
gclient, not gn. However, as of November 2020, Chromium builds for the two architectures converged and are expected to remain on the same version indefinitely, so this is now more of a historical artifact.It's possible to build on an arm Mac, without Rosetta. However, this configuration is not yet covered by bots, so it might be broken from time to time. If you run into issues, complain on https://crbug.com/1103236
Also, several of the hermetic binaries in depot_tools aren‘t available for arm yet. Most notably, vpython is not yet working (tracking bug). vpython is needed by git cl, so things like git cl upload don’t yet work on an arm Mac. The build will also use system python, python3, and git, instead of depot_tools's hermetic versions for now.
However, enough works to be able to check out and build (with goma too), with some setup.
opt in to arm64 binaries from cipd by running
echo arm64 > $(dirname $(which gclient))/.cipd_client_platform
(If you want to build tools/metrics:histograms_xml, you also need to echo arm64 > third_party/depot_tools/.cipd_client_platform in your chromium checkout. This isn't needed for building chromium or any test targets.)
opt out of vpython by running
export VPYTHON_BYPASS="manually managed python not supported by chrome operations"
With this, you should be able to run fetch chromium normally, and then build, using gn, ninja etc like normal.
gtest-based binaries should build, run, and mostly pass. Web tests probably don't work yet due to lack of an arm apache binary (tracking bug).