efi-loader ignores dtb files?

[Manuel Stühn]

While trying to get FreeBSD 12.0 up and running on a NanoPI NEO2 
(aarch64 Allwinner H5) I'm stumbling over issues with 
loader/loader.conf.  FreeBSD starts fine, but it uses the 
devicetree-blob provided by uboot/EFI. I've tried to load the FreeBSD 
one by adding these lines to loader.conf:

sun50i-h5-nanopi-neo2.dtb_load="YES"
sun50i-h5-nanopi-neo2.dtb_type="dtb"

and put the dtb file into /boot/dtb/sun50i-h5-nanopi-neo2.dtb, but this 
did not work at all.  It got completely ignored by loader. The rest of 
the file was read and applied correctly (kernel-modules i'd added for 
testing purposes were loaded correctly).

I tried to load it by hand like this:

load -t dtb sun50i-h5-nanopi-neo2.dtb

which worked, the dtb file was loaded and used. After consulting 
loader.conf(5) i found this way to load modules:

dtbfile_load="YES"
dtbfile_type="dtb"
dtbfile_name="sun50i-h5-nanopi-neo2.dtb"

and this finally triggered loader(8) to actually load the dtb.  
Unfortunatley the problem occurred again when i tried to add overlays.  
Those are, again, not recognized at all:

/boot/loader.conf:
fdt_overlays="sun50i-nanopi-neo2-codec.dtbo,sun50i-nanopi-neo2-sid.dtbo,sun50i-nanopi-neo2-ths.dtbo"

Any ideas?

BTW, is there a way to keep the u-boot logs printed before the 
FreeBSD-boot-menu gets drawn? The console gets cleared and erases some 
(valuable?) information. I was always to slow to stop the boot right 
after the last line of u-boot and the first of EFI.

--
Manuel