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.
step:
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 ./flash.sh --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
exit
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

Hi,

How do you come up with these steps?

It appears that steps were extrapolated from https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/flashing.html
The complication here is that nvidia so far did not release any official documentation for booting from nvme; However there are workarounds e.g. https://www.jetsonhacks.com/2020/05/29/jetson-xavier-nx-run-from-ssd/

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?