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
