Steps to Urbit on Raspberry Pi
You need a Raspberry Pi capable of running in AArch64 (aka 64-bit) mode, which means a RPi 3 or 4 (maybe a later model RPi 2 with the upgraded BCM2837 chip). The CPUs of earlier models will struggle with providing a smooth interactive experience, and the RPi3 and RPi2 are probably better suited to moon tasks that don’t need much responsiveness.
Be aware that running Urbit on a microSD card may contribute to a slower Urbit experience, depending on the speed of your card and the speed of the reader in your Raspberry Pi, and if you’re running anything else on the device that will compete with Urbit for disk access. On models earlier than the Raspberry Pi 4 there may be benefit to overclocking the reader interface to increase the speed the microSD card can be written to.
It’s better to avoid the microSD card and just run your Pi from a USB3 attached SSD (get an adapter that supports UASP).
It’s best to avoid buying a Raspberry Pi entirely, and to instead purchase an alternative single-board computer with sane storage options built into the board.
OS Version
This guide assumes you’re running the latest (Buster) 32-bit (armv7l) version of the default Raspberry Pi distro “Raspberry Pi OS” (previously called Raspbian) and that you’ve run sudo apt update and sudo apt full-upgrade recently.
Step One: Kernel
You need to add arm_64bit=1 to /boot/config.txt.
You can do this by running echo 'arm_64bit=1' | sudo tee -a /boot/config.txt
Make sure to not leave out the -a after tee or your /boot/config.txt file will consist of nothing but arm_64bit=1
Now reboot and your Pi will be running a 64-bit kernel.
Step Two: Import repository signing key
curl https://s3.us-east-2.amazonaws.com/urbit-on-arm/urbit-on-arm_public.gpg | sudo apt-key add -
Step Three: Apt sources
Add my Urbit on ARM repository to your apt sources:
echo 'deb [ arch=arm64 ] http://urbit-on-arm.s3-website.us-east-2.amazonaws.com buster custom' | sudo tee /etc/apt/sources.list.d/urbit-on-arm.list
Also modify your existing sources.list so it doesn’t cause apt to produce errors as it goes looking for an architecture that doesn’t exist in the Raspberry Pi OS repository:
sudo sed -zi 's/deb/deb [ arch=armhf ]/' /etc/apt/sources.list
Step Four: Enable multiarch for arm64
sudo dpkg --add-architecture arm64
Step Five: Update the package list
sudo apt update
Step Six: Actually install Urbit
sudo apt install urbit
Step Seven: Boot Your Planet
Run urbit with urbit some-planet (note there’s no ./ in front of the urbit command like when you use the usual binaries from linux64.tgz).
So booting a comet would be urbit -c mycomet and running that comet would be urbit mycomet, and booting a planet would be urbit -w sampel-palnet -k ./my-planet.key.
So you can follow the install guide from urbit.org but don’t put what it tells you to in front of the urbit part of the command.
There’s also no need to run sudo setcap 'cap_net_bind_service=+ep' to allow urbit to bind to port 80, it’s already been done for you as part of the package install process.
If your Pi doesn’t have enough ram to run urbit, create a swap file.
Step Eight: Configure TRIM timer
Raspberry Pi OS doesn’t set fstrim to run automatically, which can be a problem when combined with the way Urbit creates checkpoints; we need to discard the unused blocks from deleted checkpoint patches.
First, test if your storage device supports running fstrim.
run sudo fstrim -v / and it should produce results similar to:
/: 13.1 GiB (14027571200 bytes) trimmed
If it instead says:
/: the discard operation is not supported
then you may have an SD card that doesn’t accept TRIM commands or issues with your USB SSD adapter, which is a whole complicated thing beyond the scope of this guide (and why I recommend avoiding the Raspberry Pi and buying a device with sane storage options built into the board.)
If sudo fstrim -v / produced successful results then install a modified fstrim service package, which will attempt to TRIM all mounted filesystems daily:
sudo apt install fstrim-urbit
The Group
Join the group ~dasfeb/smol-computers if you have questions or issues.