Quote from: DouglasLourey on April 02, 2020, 18:15:29
There is a workaround to USB mass storage boot. It still requires a SD memory card, but the operating system is loaded from USB mass storage.
Assumption: Your Raspberry pi is up and running.
1. Copy the current root drive to an image file.
2. Create a ext4 partition on the USB drive
3. Copy the image file to the new ext4 partition
4. Resize the partition to size desired using GPARTED.
5. Edit fstab files to mount the new partition as / (There are two of them)
6. Edit /boot/cmdline.txt and change /dev/mmcblk0p2 to /dev/sda1
Line six is the trick to boot from USB mass storage.
These are my notes for my Banana Pi, so some details must be changed for the Raspberry Pi, but both boards are similar.
BerryBoot makes this even easier and doable in a GUI, plus you can do multiboot easily. Leepspvideo has a quick video on YouTube about it.
This site won't let me post links, but it's called "EASY SSD Install Raspberry Pi 4. BerryBoot 2.0 part 2"