Relating BR_CID on host to value readable on the Jetson

[h123]

Hi,

Is it possible to relate the BR_CID value that can be seen on the host when flashing the Jetson in recovery mode, to a value that can be read by a script that is running on the jetson itself afterwards? I have looked at the sysfs files exposed by the tegra-fuse kernel module, but I don’t see a directly link between that and the BR_CID. It would be very helpful for us to automate our mass flashing and system bring up.

Another unrelated question which might also solve our problem, is it possible to dump the EEPROM contents of the module by using the tools in the mass flashing archive? In that way we could also use the identifier of the module or it’s mac address.

Thanks!

[WayneWWW]

Hi,

May I ask what is your exact request? Do you want to dump the BR_CID value during flash and dump each eeprom content during massflash?

For single device case, you can use command,

$ sudo ./tegrarcm_v2 --uid

It returns a 128-bit ECID. BR_CID is the lower 100 bits.

[h123]

Hi WayneWWW,

Is it possible to get this same ID (or part of it, as long as it is unique) in a script running on the Jetson? By reading for example some sysfs files, or running some nvidia tool?

I was looking at the ID that can be read with:

cat /sys/module/tegra_fuse/parameters/tegra_chip_uid

But I don’t see a relation with the BR_CID.

[WayneWWW]

What is your usecase for searching it in kernel?

[h123]

It would make configuration after flashing easier. The Jetson could then fetch its configuration directly from one of our internal databases without having to communicate with the host. (Any unique ID would work for this like MAC address, Jetson SoM ID, but for those I haven’t found an easy way to read them on the flashing host when the jetson is in recovery mode using tools from the massflash archive).

The approach would be more or less. 1) Connect unit to flashing host. 2) Scan barcode on unit. 3) Store a link between barcode and BR_CID. 4) Flash Jetson. 5) When Jetson boots it can retrieve the barcode of the unit it is installed in together with all required metadata based on this BR_CID.

[Bibek]

@WayneWWW

BR_CID

you can read from cat /proc/device-tree/chosen/ecid

[h123]

Thanks a lot! I read that file and can confirm that it contains part of the BR_CID.