Earlier this week, the Raspberry Pi Foundation announced the beta release of a new firmware update featuring a bootloader with USB boot support on the Raspberry Pi 4. This new update should make the USB boot process much easier to set up on the latest Raspberry Pi.
Update (5/23): We now have a dedicated tutorial on how to boot Raspberry Pi 4 From USB that has detailed instructions for doing this.
While we've run the Raspberry Pi off an SSD before, the Raspberry Pi 4 has lacked USB boot functionality since launch. This new update will allow complete USB boot support, eliminating the need for a microSD card entirely. With the beta firmware, Pi 4 owners can boot operating systems using USB 3.0. You can see full details about how bootloader configurations on the Raspberry Pi website.
How to Boot Raspberry Pi Off USB
If you want to be able to boot your Raspberry Pi off USB, take note of the below.
Since this is a beta, early adopters have to manually update the bootloader. The process is easy enough, though. You'll need to load the latest edition of the Raspbian operating system onto a microSD card and run the firmware update from a terminal. After rebooting, the new beta bootloader will go into effect.
If you'd like to get in on the beta, follow the detailed steps in our tutorial. You will need a microSD card to enable the new USB functions, but after that, the microSD card is totally optional.