Version tracking of tegra124-jetson-tk1.dtb?

[John Klos <john%ziaspace.com@localhost>]

Hi, all,

I recently updated two of my Jetson TK1 systems to NetBSD 8.0 from 8.0 
BETA. One was from late last year, and the other from late 2016 / early 
2017.

The late last year update showed a new error:

xhci0: couldn't load firmware from 'nvidia/tegra124/xusb.bin': 2

But since I'm not using USB, I didn't concern myself with that just yet.

The one from 2016 / early 2017 didn't show that error, but it locked up 
hard after a short amount of time (about 15 minutes). Attempts to get in 
to the debugger by sending a break on the serial console gave just a 
single line:

Stopped in pid 0.33 (system) at netbsd:cpu_Debugger+0x4:

but there was absolutely no response after that. The system had to be 
power cycled.

On a hunch, I had the power cycled, then I quickly replaced 
tegra124-jetson-tk1.dtb with a newer one before the system crashed. Now, 
the system doesn't crash.

While timestamps on MS-DOS FAT filesystems don't tell much, they do at 
least tell when the file was placed, so I know that the working 
tegra124-jetson-tk1.dtb from the newer machine is no newer than 
9-December-2017 (68422 bytes). The old one was no newer than 
27-September-2016.

First: does the out of date dtb sound like a reasonable explanation for 
lockups? If so, do we know why the debugger wouldn't work via serial?

Second: Is there a chance that the ethernet not attaching once every three 
or four boots is related to the age of the dtb? Should I update to the 
latest dtb from NetBSD 8.0?

Third: Is there a way to get a version from a tegra124-jetson-tk1.dtb 
file? The file command gives:

/boot/tegra124-jetson-tk1.dtb: Device Tree Blob version 17, size=68422, 
boot CPU=0, string block size=3294, DT structure block size=64048

Fourth: From where do we get xusb.bin? Is that path relative to 
/libdata/firmware/? I've never seen that before?

Thanks,
John