I'm booting my Raspberry Pi 4 from a USB SSD

September 2020 Update: USB boot is out of beta! Check out this video for simplified instructions. All you need to do now is run sudo apt-get dist-upgrade -y, then reboot, then your firmware should be up to date. Now, flash any USB drive with the latest Raspberry Pi OS, plug it into your Pi (unplugging any microSD card), and you're off to the races!

Recently, the Raspberry Pi Foundation announced a USB boot beta for the Raspberry Pi 4. For a very long time, the top complaint I've had with the Raspberry Pi is limited I/O speed (especially for the main boot volume). And on older Pis, with the maximum external disk speed limited especially by the USB 2.0 bus—which was shared with the network adapter, limiting its bandwidth further—even USB booting didn't make things amazing.

Upgrade the Raspberry Pi 4's firmware / bootloader for better thermals

In October, the Raspberry Pi Foundation released an updated bootloader/firmware for the Raspberry Pi 4 which dramatically reduces power consumption and overall temperatures on the Pi 4 by setting the USB controller and CPU into a more power-friendly mode.

I wanted to post here the instructions for checking the current version, and upgrading, because I have a large number of Pis to upgrade over time, and I needed a quick reference. For more details, check out the Raspberry Pi Documentation page Raspberry Pi 4 boot EEPROM.

Checking if the current bootloader is up to date

Upgrade system packages and install the rpi-eeprom utility:

$ sudo apt update
$ sudo apt -y full-upgrade
$ sudo apt install -y rpi-eeprom

Check if an update is required:

$ sudo rpi-eeprom-update

If you see a difference in the output, you can restart to update to the newer version. If everything's the same, you're already on the latest version.