Serial Configuration for firmware + UEFI debug info?

[ballanty]

I'm attempting a supported configuration: UEFI + FreeBSD. I'm starting with just a single boot (FAT32) partition with the release 0.3 version of UEFI and no other partitions on the SD card.

When I connect HDMI monitor and USB keyboard I can see the video cycle (backlight on/off but no actual output of any kind).

I've attached a usb serial adapter to GPIO 14/15 (I don't have the funny special RPI5 cable for the dedicated serial). I've modified config.txt to contain:
dtparam=uart0
dtparam=uart0_console
(based on instruction to get GPIO14/15 to be the console).
I've done this to see debug info and perhaps figure out what's going on but I get no serial output.

I've confirmed the serial cable operational by booting a Debian SD card in the same RPI5 (with the same config options).

Q1: What settings should be set in config.txt to get serial output from firmware/UEFI?

Q2: I've assumed that UEFI doesn't require a second partition with an OS on it to function properly. Is this true?

[bzfbd]

Hi, trying to attempt the same to get UEFI on serial via GPIO pins. Have you figured it out?