UEFI boot hang - what to test next?

[Jaromír Doleček <jaromir.dolecek%gmail.com@localhost>]

Hi,

I have a test machine where I'm able to boot NetBSD in legacy mode
just fine, but the boot hangs when booted from an UEFI-enabled media
in UEFI mode.

I investigated with custom efiboot, it seems it hangs right after
efibootx64 executes the loaded kernel via startprog() in lib/exec.c.

Any ideas what I could do to debug this further?

Jaromir