How to check if the bootloader in SD card is deleted? How to put it back?


I am working on a project in a nano board. I forgot if this SD card still have the bootloader inside. How can I check it?
If there is no bootloader, then, if I clone this SD card, it cannot be used in another nano board…
Can I put back the bootloader?
Is there any Plan B if there is no bootloader and I cannot add it back?


You can only re-install another sdcard image.

I need to clone that SD card for 30 new Nvidia Nano boards…
I don’t have any new Nvidia Nano board, how can I verify if there is a bootloader inside the SD card?
Will Gpart work? Thx

The SD card model of Nano (and SD card model of NX) has QSPI memory on the module itself. Not all of the required boot content is on the SD card. In older releases more content was on the SD card, and less on QSPI, but in more recent releases most (all?) boot content is in QSPI and not on the SD card (aside from rootfs). There is no possibility of just an SD card working to determine boot. You have to use flash (with a matching release of software to work with the SD content) to put the required version of boot content on the module’s QSPI. It is questionable whether the content you are speaking of is even on the SD card.

The above is why a cloned SD card of one release will work with some Nanos which have required QSPI content, but not others which would need different SD card content. If the SD card you have is not working on a different Nano, then find the L4T version of the working unit (see “head -n 1 /etc/nv_tegra_release”), and flash the non-working unit with that release…then the SD card should work.

You can find the JetPack/SDKM releases and L4T releases (L4T is what JetPack/SDKM actually flashes) here:


I don’t mind to do more work as soon as it works.
Here is my plan.

  1. Keep using this SD card as the master for the clone
  2. If the clone SD card does not work on a new Nvidia board, I use an another new SD card with a fresh 4.6 image to boot the new nano module. (I assume the bootloader will be copied to the module)
  3. Then, the clone SD card should work afterward, right?

Do I need to keep burning new SD card with a fresh 4.6 or I can prevent the bootloader be deleted in the SD card?


A 4.6 SD card will only work on a unit which has QSPI memory for that release. If a unit does not work with 4.6 (because of QSPI release being wrong), then it won’t matter how many 4.6 release SD cards you use, it won’t work. You’d have to either (A) use an older release SD card matching the QSPI release, or else (B) flash the Nano itself so that QSPI works with the 4.6 SD card (then you won’t need another SD card).

Bootloaders are not copied when an SD card is copied.

Thx. All my SD card is using 4.6. So, I assume my method will work?

The method will work only if all of the Jetsons were flashed with 4.6 (or a recent release). Did you flash the failing Jetson? It is an SD card model, but you still need to flash the actual Jetson. If all Jetsons are flashed with that release, then the SD cards generated based on 4.6 should work on all of them.

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