Jetson Nano notes

Kia ora koutou,
Here is some more information I learned about getting NetBSD to run on
the Jetson Nano. Better late than never I guess.

While I was out for a walk the other day I remembered seeing something
about Tegra 210s and PCI buses in a U-Boot script when fiddling with a
Raspberry Pi. Sure enough, when I run "pci enum" in U-Boot it seems to
prevent the NetBSD panic when attaching the PCIe bus.

I found that not was my DTB file not being loaded, but neither was the
one that is already on the NetBSD image. I have seen some other boards
run somewhat board independent U-Boot scripts stored in their default
environment to set $fdtfile based on the vendor, board and soc names.
The Jetson Nano does not have this. What it does have is a script that
passes in U-Boot's own devicetree to the O/S being booted if $fdtfile
isn't set.

The NetBSD devicetree has one wrong SDHCI controller enabled causing
the kernel to hang. 

The NetBSD kernel doesn't detect the µSD card which does make mounting
root impossible. I tried using a USB drive and that was worse with U-
Boot having significant difficulty accessing the USB bus. I haven't
tried netboot the Jetson Nano yet.

At some point I'll create low priority PRs for the problems I think
that NetBSD needs to fix.

Ngā mihi,
Lloyd