Like many people I’m excited by all of the possibilities opened up with WebAssembly/WASM. Most recently I’ve been keeping an eye on Wasmer and similar projects that enable WASM outside of the browser.
So when I saw that you can now run it on a Raspberry Pi, I had to give it a try. But it’s not quite as straightforward as the article suggests and this is what I had to do to get it working.
I did all of these steps on a 4GB Pi 4 running the latest version of Raspbian Buster.
- First, you have to switch to a 64-bit kernel to get started. That’s pretty easy. Edit /boot/config.txt and add the line
arm_64bit=1. Then reboot - I’m not sure if it’s needed but I did a full
sudo rpi-configtoo to update. And rebooted again. - But this isn’t enough because the Pi still uses a 32-bit userland. Even if you successfully run the Wasmer installer, the wasmer binary won’t run. I read lots of threads with lots of complicated setups involving Docker and other distros etc but it turns out that the solution is just chroot. And luckily someone else figured out those details.
- So you just need to do the following:
sudo apt install -y debootstrap schroot
cat << EOF | sudo tee /etc/schroot/chroot.d/pi64
[pi64]
description=V3D arm64 testing
type=directory
directory=/srv/chroot/pi64
users=pi
root-groups=root
profile=desktop
personality=linux
preserve-environment=true
EOF
sudo debootstrap --arch=arm64 buster /srv/chroot/pi64
sudo schroot -c pi64 -- apt install -y curl sudo
schroot -c pi64
- You are now running in a 64-bit shell so you can now install Wasmer with
curl https://get.wasmer.io -sSfL | sh
- and then install and run rustpython
$ source /home/pi/.wasmer/wasmer.sh
$ wapm install rustpython
$ wapm run rustpython
>>>>> 2+2
4
That’s incredibly cool. A Rust version of Python running via WebAssembly on a <$70 computer.
Note tho that this mixed 64-bit and 32-bit setup is still experimental and I’ve seen some glitches like the Raspbian file manager crashing at launch.