Xavier NX booted from external nvme, how do I back up my custom rootfs?

[andorno]

https://docs.nvidia.com/jetson/archives/r35.3.1/DeveloperGuide/text/SD/FlashingSupport.html#cloning-rootfs-with-initrd
I backed up system.img.raw by following the instructions in the link above, but an error occurred when mounting the root file system, prompting can’t read superblock on /dev/loop25.

What is the reason for this?

[DaveYYY]

Hi,

why are you mounting it?
You just replace the system.img into the BSP folder, so the rootfs will be the same after re-flash.

Please don’t try something that is not in the document and ask us why it does not work.

[andorno]

The roofs had customized, I want to generate the OTA update payload package.

[DaveYYY]

Hi,

then it’s pointless to backup the entire rootfs, because it will be cleaned up during the process of OTA, and if you flash it back with the image you backup, the device will be downgraded to the original version.

I think you should just manually copy files you need to somewhere else, and copy them back after OTA is done. Or check this tool to automate the process:
https://docs.nvidia.com/jetson/archives/r35.3.1/DeveloperGuide/text/SD/SoftwarePackagesAndTheUpdateMechanism.html#back-up-and-restore-files-on-the-app-partition