I have a Raspbian OS microSD card that I use with the Raspberry Pi 8GB model
I upgraded the firmware to the June-15 stable version of the firmware so that I could boot from the SSD. That worked fine.
The SSD is a Kingston A400 SATA III SSD (120GB) and is attached via a USB 3.0 to SATA connector. I basically followed the procedure from the YouTube: Explaining Computers: Raspberry Pi 4 8GB and USB Boot using the same hardware.
However, today I tried booting from a microSD card with the SSD attached.
It did not boot. The solid red light appeared but the flashing green light did not. When removing the microSD card and booting, the same behavior was observed. Only when I detached the SSD, did the flashing green light display. I was able to boot from microSD when the SSD was not attached.
My understanding is that the boot order is "microSD card" first and then any attached USB devices. Is this correct? If so, it should have worked right?
I thought the problem might be the firmware, so I upgraded to the 31-JUL stable version of the firmware. With the bootable microSD card in place and the non-bootable SSD attached, I see a different behavior. I now get to screen which says the following.
You are in emergency mode. After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode. Cannot open access to console, the root account is locked. See sulogin(8) man page for more details. Press Enter to continue.
Am I correct in assuming this to be a firmware bug?