How does Xavier boot the system from NVME SSD

I refer to the “NVIDIA Jetson Linux Developer Guide ”documentation, Flashing and Booting the Target Device- Flashing to a Flash Drive
I use a 250GB NVME SSD,parted 50GB for file system.
1、 SSD plugged into xavier
sudo fdisk -l ,I know that SSD is nvme0n1
2、Create a new GPT
sudo parted /dev/nvme0n1 mklabel gpt
3、Add the APP partition
sudo parted /dev/nvme0n1 mkpart kernel APP 0GB 50GB
get 50GB nvme0n1p1
4、sudo mkfs.ext4 /dev/nvme0n1p1
$ sudo mount /dev/nvme0n1 /mnt
5、 I already copied rootfs to SD on the host as follows
Put the Jetson device into recovery mode, then enter the following commands to generate the rootfs without flashing the device:

$ sudo BOOTDEV=nvme0n1p1 ./ --no-flash rtso-1001 nvme0n1p1 (Custom board)

$ sudo mkdir tmp_system

$ sudo mount bootloader/system.img.raw ./tmp_system

sudo cp -r ./tmp_system/* /SDcard/ 6、 Plug SDCARD into Xavier SDCARD all files copy to /mnt 7、When the copy is complete,check /mnt/boot/extlinux/extlinux.conf APPEND {cbootargs} root=/dev/nvme0n1p1 rw rootwait rootfstype=ext4
8、sudo umount /mnt
9、Check partition UUID
sudo blkid /dev/nvme0n1p1
9、host pc
Copy PARTUUID to bootloader/l4t-rootfs-uuid.txt
10、sudo ./flash rtso-1001 external ( Custom board)
11、can not start
Timed out waiting for devices dev-ttyGS0.device
DEPEND dependency failed for serial Getty on ttyGS0


How do you come up with these steps?

It appears that steps were extrapolated from
The complication here is that nvidia so far did not release any official documentation for booting from nvme; However there are workarounds e.g.

You can try these steps here.

Please note that this method is boot “rootfs” from nvme drive. The kernel is still on emmc.

thank you very much
I know what’s causing it,Copying the root file system requires the dd command

thank you very much
I referred to this document earlier,I know what’s causing it,Copying the root file system requires the dd command

Any plans to enable kernel too boot from NVME?