James Chambers announces the latest version of Raspberry Pi OS (formerly Raspbian) allows the Raspberry Pi 4 to boot from an offboard disk is available.
The new Raspberry Pi 4 bootloader has finally come out of beta and made its way into the official latest Raspbian! This has been long awaited since when the Raspberry Pi 4 was released it had no native support for booting from USB / Network but it was promised right from the start it would get it through a later update.
The magic requires a firmware update. Then an edit to the rpi-eeprom-config file to specify how you’re looking to boot.
Finally, only certain USB adapters are known to work (as there are many different chipsets, only supporting the most common ones is to be expected).