Pin 10 - UART RX signal being interpreted as keyboard input

[angaz]

I would like to make this issue as informational. I'm not sure where to put it.

When U-Boot (and systemd-boot) starts, you can interrupt the boot by pressing a key, and this functionality gets triggered by pin 10 (UART RX) being connected. This means that having pin 10 connected effectively stops the Pi from booting. Disconnecting this pin solved the stuck boot problem.

I'm not sure where would be the best place in the docs to put this information. Maybe as a footnote on the pinout wiring diagram? I just thought it would be useful for someone else running into the same issue.