How to copy rootfs in that NX-emmc witch boot up form SDMMC3

[chenglong.jiang108]

hi，
We have some questions about the use of sdmmc3, hope you can provide some guidance.

Now, we have successfully enabled sdmmc3 in Jeston Xavier NX emmc. It can be I/O or used as rootfs.We used this approach in the forum.

How to Boot From SD Card? - #17 by carolyuu

@carolyuu

Hi hijikata_M,

I can boot up from SD card, list steps for you reference:

$ sudo mkfs.ext4 /dev/sd<port><device_number>   #Format your device with an Ext4 file system
$ cd Linux_for_Tegra/rootfs/
$ sudo cp -a * <mntpoint> && sync
$ Unmount the disk and connect it to the target Tegra device
$ sudo ./flash.sh jetson-xavier mmcblk1p1

Please check your sdcard format or try to format and copy again.
Thanks!

Although it is working now, we still have some questions about it：

1. Can we copy the content in the SDCARD that has been used to get a SDCARD with the same content? And bootup from this new SDCARD? .We have tried to copy a used rootfs to another card through the command “sudo cp -a * && sync”. Unfortunately this doesn’t work.
   We hope to make an image file containing some software, and it can be copied to more SDCARDs to boot NX.Can you give some suggestions?

2. You seem to mention in the forum that external storage cannot be upgraded via OTA

Boot from external drive

@WayneWWW

6. Official OTA upgrade does not support boot from external
Your “boot from external” setting would be gone after you try the apt upgrade. Because our OTA debian package by default only supports the boot from default path (emmc/sd).

Can this problem be avoided ?

[WayneWWW]

1. Please refer to

How to create a distributable image of a SD card for Jetson Nano

2. Actually, this question is a little lacking of thinking. “Official” OTA upgrade does not know your board design. Using it to upgrade the system will break your system. For example, your sdmmc3 will be gone. No need to think about mounting from it, since it does not exist.
   Official OTA upgrade is just a template. The correct way is you should study some knowledge of debian package and create your own debian package, put it on your OTA server and use it to update the system instead of using the official one.