Booting UEFI ZFS is broken on arm64

It appears that in the latest FreeBSD 12-CURRENT/arm64 snapshot,
booting UEFI GPT ZFS on my OverDrive 1000 is broken. It boots up to
this line:

Using DTB provided by EFI at 0x801fe00000.

Then all output stops. I'm in the process of building a custom install
ISO that has DEBUG turned on in the fdt code. I hope to report back
soon-ish, unless anyone else has any ideas as to what could be wrong.

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

GPG Key ID:          0x6A84658F52456EEE
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