NetBSD evbarm - Help with Raspberry Pi 4 installation and build

[Lee de Byl <lee%32kb.net@localhost>]

Hello everyone,

I am hoping I could get some kind assistance with understanding the installation and boot process for NetBSD on the Raspberry Pi 4. I have had success running NetBSD 9 on the Raspberry Pi 3B, but have come across some problems with the RPi 4 (4GB).

Forgive me if the answers to these questions are trivial, but I'm relatively new to both the RPi4 and NetBSD generally.

I have been following the documentation here: https://wiki.netbsd.org/ports/evbarm/raspberry_pi/ I've had success with Jun Ebihara's images on the RPi 4, but ideally I'd like to use one of the generic images, and boot directly from a USB SSD without the need for an SD card.

A few things aren't clear to me:

* What is the purpose of the UEFI firmware, and why is it required for the RPi 4 but not the RPi ?

* Are any of the stable released supported on the RPi 4 (the above page says "NetBSD 9: aarch64 support (RPI3, and should work on all supported systems with 64-bit CPUs)" - does the RPi4 have a supported CPU?

In terms of installing from a generic arm64.img, the page above states:

"The Raspberry Pi 4 requires the UEFI firmware. Write the UEFI firmware to the SD card, and then insert an USB drive with the standard NetBSD arm64.img written to it. The Pi will then boot from USB."

If I follow these instructions, the system boots, but halts early in the boot process with a "GIC Error". It appears to halt before any file systems are mounted. This is using a prebuilt arm64 NetBSD Current build. Is there something I've missed? 

Would appreciate any help and guidance on how to have the best experience with NetBSD on the RPi 4. ultimately I'm looking to use it as a simple headless server for http/gopher/dns.

Thanks in advance,
Lee