Disable Display Output

Disable Graphical Desktop

In server, NAS, soft router, or embedded scenarios, a graphical desktop (GUI) is usually not required. Disabling the GUI can significantly reduce resource usage, improve system stability, and remove unnecessary background services.

When This Is Recommended

• Radxa SBC is used as a server, NAS, or soft router
• You only manage the system via SSH
• You want to reduce memory and CPU usage and speed up boot
• You do not need local HDMI display or desktop environment

Important Notes Before You Start

Before disabling the graphical desktop, it is strongly recommended to prepare and verify serial console access first, so that even if network or SSH fails, you can still log in through the serial port.

Platform Limitations

On the following SoC platforms:

• Allwinner A733
• CIX P1

Currently, character console output via TTY / Framebuffer is not supported. After disabling the GUI:

• HDMI will not show a text login prompt
• You cannot log in or operate the system via a local display
• The system can only be managed via SSH or serial console

Risk Warning

If any of the following issues occur after disabling the GUI:

• SSH service is not started or misconfigured
• Network configuration is wrong and the board cannot obtain an IP address
• systemd default target is misconfigured
• Critical system services are accidentally disabled

Then you will not get any visible output on HDMI.

In these cases, a serial debug cable is the only way to recover the system locally.

Recommended Procedure

1. Prepare and connect a USB-to-TTL serial cable (3.3 V level)
2. Confirm:
   • Boot logs are printed to the serial port
   • You can log in to the system via serial console
3. In the current network environment, confirm that SSH connection is stable and available
4. Only then proceed to disable the GUI

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Check Current System Boot Mode

Check the current default systemd target:

systemctl get-default

Common values:

• graphical.target: graphical desktop mode (default)
• multi-user.target: command-line mode

Temporarily Disable GUI (Without Changing Default)

Disable GUI only for the current boot session:

sudo systemctl isolate multi-user.target

Notes:

• The graphical desktop will exit immediately
• After reboot, the system will still enter graphical mode
• Suitable for testing
• Make sure you have disabled automatic sleep / suspend before running this command

Permanently Disable GUI (Recommended)

Set the default target to command-line mode:

sudo systemctl set-default multi-user.target

This makes the system boot directly into CLI mode every time, without starting the desktop environment.

Reboot and verify:

sudo reboot

After boot, you should see the following behavior:

• HDMI does not show desktop or text console
• The system is running normally
• You can log in via SSH or serial console

To restore graphical boot mode:

sudo systemctl set-default graphical.target

Disable Display Manager (Optional)

To further reduce background services, you can disable the display manager.

Common display managers include:

• lightdm
• gdm3
• sddm

Check the currently enabled display manager:

systemctl list-units --type=service | grep -E "lightdm|gdm|sddm"

Disable gdm as an example:

sudo systemctl disable gdm.service
sudo systemctl stop gdm.service

Restore the display manager:

sudo apt reinstall gdm3

Other display managers can be disabled in a similar way (restore by reinstalling or using systemctl enable + systemctl start).

Uninstall Desktop Environment (Optional)

If you are sure you do not need the GUI in the long term, you can uninstall desktop-related components to free up storage space.

warning

Note: This operation is irreversible. Only do this when you clearly understand the requirements and already have reliable SSH or serial login access.

sudo apt purge task-desktop lightdm gdm3 sddm
sudo apt autoremove

How to Restore the GUI

If you only changed the systemd default target:

sudo systemctl set-default graphical.target
sudo reboot

If the desktop environment has been removed, you need to reinstall the corresponding desktop packages first, and then switch back to graphical.target.