Weston GUI display when using NFS rootfs

[#1]

Default system can’t start Weston GUI in monitor after booting with NFS, so I find a solution to fix that issue.
1.Error messages
imx8mpevk login: [31.274389] systemd[1]:weston@root.service: Main process exited, code=exited, status=1/FAILURE
[ 31.274928] systemd[1]: weston@root.service: Failed with result 'exit-code'.
[04:52:59.571] logind: not running in a systemd session
[04:52:59.571] logind: cannot setup systemd-logind helper (-61), using legacy fallback
2.Steps
Step 1:Add output in the /etc/xdg/weston/Weston.ini
[output]
name=HDMI-A-1
mode=1920x1080@60
Step 2:ls /sys/class/drm
There will be some device nodes like card0,card1-HDMI-A-1. card1-HDMI-A-1 is we need.
Step 3:Change drm_device in /etc/xdg/weston/Weston.ini
drm-device=card1
Step 4:Set envs
export WESTON_DRM_PRIMARY=HDMI-A-1
export WESTON_DRM_MIRROR=1
export WESTON_DRM_KEEP_RATIO=1
export WESTON_DRM_PREFER_EXTERNAL=1
export WESTON_DRM_PREFER_EXTERNAL_DUAL=1
Step 5:Start Weston
weston --tty=7 -B=drm-backend.so --idle-time=0&