Building Swift on ARM

A few, very simple, bash scripts to clone, configure and build Swift on ARM devices.

Derived from package-swift by @iachievedit, some patches from swift-arm by @hpux735.

Currently this project builds Swift 3.1.1 on Ubuntu Mate 16.04.x (get it here), Raspbian/Stretch (get it here for ARMv7 or here for ARMv6) and usually on other Debian-based distributions as well. SPM compiles correctly for both but the REPL is, as usual, not available.

Compiling 3.1.1 on Raspbian Stretch requires an additional libdispatch patch available under swift-corelibs-libdispatch.diff/raspbian/, apply it with patch -p1 < ../swift-corelibs-libdispatch.diffs/raspbian/c01599944879e58556a6e34585ac6539f5e83000_no_membarrier.diff from the libdispatch directory.

For the latest updates on Swift on ARM, check out my blog here.

Check out Helge Heß's project dockSwiftOnARM to build Swift in a Docker container or to build a cross-compiling toolchain that will allow you to build arm binaries directly from your Mac using a precompiled swiftc for ARM.

The scripts:

• clone.sh - Install dependencies and clones the main Swift repository and all the related projects

• checkoutRelease.sh - Resets all repos, updates them, checks out a specific tag (3.1.1 at the moment) and apply the patches

• build.sh - Build

• clean.sh - Clean all build artifacts

Building instructions

First of all, use a suitably sized sd-card, at least 16Gb in size.

Configure a swap file of at least 2Gb, on Ubuntu:

sudo fallocate -l 2G swapfile
sudo chmod 600 swapfile
sudo mkswap swapfile
sudo swapon swapfile

You'll need to manually enable the swap file with swapon each time you reboot the RaspberryPi (or the system will just run without swap).

On Raspbian, open /etc/dphys-swapfile and edit:

CONF_SWAPSIZE=2048

Save the file and:

sudo /etc/init.d/dphys-swapfile stop
sudo /etc/init.d/dphys-swapfile start

Now, call the included scripts as follows:

1. Launch clone.sh that will install the required dependencies (git cmake ninja-build clang-3.8 python uuid-dev libicu-dev icu-devtools libbsd-dev libedit-dev libxml2-dev libsqlite3-dev swig libpython-dev libncurses5-dev pkg-config libblocksruntime-dev libcurl4-openssl-dev autoconf libtool systemtap-sdt-dev), fix clang links and clone apple/swift with all its dependecies.

2. Run checkoutRelease.sh that will select the current release (3.1.1) and apply the needed patches. These patches cover the basic Raspi2/3 with Xenial case, but I've had many reports of successful build on different setups, but beware, additional patches could be needed on different boards/OSs. I recommend to just try and if you get an error, verify if one of the additional patches (not normally applied by checkoutRelease.sh) in the subdirectories of the <failing_component>.diffs can solve your issue. To apply it manually going in the <failing_component> directory and run patch -p1 < ../<failing_component>.diffs/otherdebians/fix.diff.

3. Once done, start the build with build.sh.

4. Once the build completes a few hours later, you'll have a swift-3.1.1.tgz archive containing the whole Swift compiler distribution. Once decompressed you'll find the Swift binaries under usr/bin.

I recommend to perform all these operations in a permanent background tmux or screen session (CTRL+B d to detach from the session and tmux a to reattach to it when you ssh again into the RaspberryPi).

Additional steps could be required in some cases (on a RaspberryPi 1 or for Raspbian) check the latest ARM posts on my blog for additional info.

If you plan to build 4.0+ and if your cmake is older than 3.6.x (Ubuntu Mate ships with 3.5.2), you'll also need to download and compile from sources a newer release of cmake, I recommend 3.7.2.

To build a different release than the one currently configured in the script, open checkoutRelease.sh and build.sh and modify the variables on top, with the branch name for the release and the release name for the tgz respectively.