Flashing image to a particular device which is not on-board eMMC/SDcard/NFS device/USB drive

Hi, I have my designed carrier board and an Xavier NX module (board ID 3668 , version 200, sku 0001, revision H.0).
On my carrier board, we have a external eMMC which goes through SDMMC pins (229/227/219/221/223/225).
We plan to flash :
1. bootloader to on-board eMMC.
2. rootfs to external eMMC.
by using one command such as ‘./flash.sh my-board-def mmcblkXpX’.

My question is:

  1. How can I know if TBoot can recognize this external eMMC ? Any tool can I use ?
  2. Could you please tell what interface that on-board eMMC and on-board SD card use ?
    sdhci@340600000/sdhci@34400000/sdhci@34000 ?
    Which one is used for SDMMC pins (229/227/219/221/223/225) in MB1/TBoot?
    How can I enable SDMMC pins for earlier booting program such as MB1/TBoot/Cboot?

Or if there is any guide line , please help to provide it.

I need to clarify some points here.

  1. Currently. it is not possible to let flash.sh flash rootfs to any of external storage. A external storage means it is not a default boot device. Thus, except the default sdcard (nano/nx) and default emmc, other interfaces are all “external device”.

  2. /flash.sh my-board-def mmcblkXpX

This command does not flash anything to mmcblkXpX. It just tells the kernel that the rootfs is on the mmcblkXpX. And kernel will mount the rootfs from that place. The current method is to let you prepare the the rootfs from host.

  1. Thus, for your plan,
  1. bootloader to on-board eMMC. → It is possible because this is default setting.
  2. rootfs to external eMMC. → You can only boot into your internal emmc first, copy the rootfs to the external emmc and see if setting root=mmcblkXpX in kernel command line can work or not.
  1. For your question
  1. How can I know if TBoot can recognize this external eMMC ? Any tool can I use ?

Sorry, this is not supported.

  1. Could you please tell what interface that on-board eMMC and on-board SD card use ?
    sdhci@340600000/sdhci@34400000/sdhci@34000 ?

You can check the device tree and there is one that is enabled by default.

  1. Or if there is any guide line , please help to provide it.

All the document is on the download center. The design guide can tell you the answer.