Desktop Environment and Display

Debian GNOME/KDE/Xfce desktop is lagging/slow

A lagging desktop environment can be caused by various factors, most commonly related to graphics drivers, system resource usage, and desktop effects.

Troubleshooting and Optimization Methods:

1. Install the correct graphics drivers:

   • This is the most important step. Whether you have an NVIDIA or AMD graphics card, installing the official or proprietary drivers usually brings a significant performance boost, especially for 3D acceleration and video playback.
   • Please refer to the How to install NVIDIA drivers on Debian tutorial further down this page. For AMD graphics cards, installing the firmware-amd-graphics package is usually sufficient.

     sudo apt install firmware-amd-graphics

2. Disable or reduce desktop effects:

   • GNOME: Animations in GNOME can be turned off using the gnome-tweaks tool.

     sudo apt install gnome-tweaks

     Open "Tweaks" -> "Appearance" or "General", find and turn off the "Animations" option.
   • KDE Plasma: Go to "System Settings" -> "Workspace Behavior" -> "Desktop Effects". You can disable resource-intensive effects like "Blur", "Background Contrast", and "Wobbly Windows". You can also temporarily disable all desktop effects with the Alt+Shift+F12 shortcut.
   • Xfce: Go to "Settings" -> "Window Manager Tweaks" -> "Compositor". You can disable effects like window shadows and fades.

3. Check system resource usage:

   • Use the top or htop (requires sudo apt install htop) command to see which process is consuming a lot of CPU or memory.
   • Sometimes, a specific browser tab, an unoptimized application, or tracker (GNOME's file indexing service) can cause lag.

4. Choose a more lightweight desktop environment:

   • If your hardware is indeed quite old and GNOME/KDE is still lagging after optimization, consider switching to a lighter desktop environment like Xfce or LXQt.

     # Install Xfce
     sudo apt install task-xfce-desktop
     # Install LXQt
     sudo apt install task-lxqt-desktop

     After installation, you can choose which desktop environment to log into from the login screen.

Debian taskbar/panel has disappeared

This is usually caused by the panel process crashing or a configuration error.

Solutions:

• GNOME:

  • GNOME's top bar and Dash (favorites bar) are managed by the core gnome-shell process. If they disappear, it usually means the entire shell has crashed.
  • Press Alt+F2, type r in the run dialog, and press Enter. This command restarts gnome-shell and usually restores the interface.
  • If that doesn't work, an incompatible GNOME extension might be causing the crash. Try disabling all third-party extensions through gnome-tweaks or the extensions website, then re-enable them one by one to find the culprit.

• KDE Plasma:

  • Plasma's panel is managed by the plasmashell process.
  • You can try restarting it. Press Alt+Space or Alt+F2 to bring up KRunner, then type:

    killall plasmashell && kstart5 plasmashell

    Or more simply:

    plasmashell --replace &

  • If the panel configuration is messed up, you can try resetting it to the default. This will clear all your customizations to panels and widgets, so proceed with caution.

    rm ~/.config/plasma-org.kde.plasma.desktop-appletsrc
    # Then restart plasmashell

• Xfce:

  • Xfce's panel is xfce4-panel.
  • Try running xfce4-panel in a terminal to see if it starts.
  • If the panel configuration is corrupted, you can reset it:

    xfce4-panel --quit
    rm -rf ~/.config/xfce4/panel
    xfce4-panel

    This will restore the default Xfce panel layout.

How to change desktop wallpaper/theme in Debian

• Wallpaper:

  • General: Right-click on an empty area of the desktop, and you will usually find options like "Change Desktop Background", "Configure Desktop and Wallpaper", or similar.
  • GNOME: Right-click desktop -> "Change Background".
  • KDE Plasma: Right-click desktop -> "Configure Desktop and Wallpaper".
  • Xfce: Right-click desktop -> "Desktop Settings".

• Theme:

  • Themes usually consist of several parts: application style (GTK theme), icon theme, cursor theme, and Shell theme (specifically for GNOME's top bar, etc.).
  • Installing themes:
    • Many themes can be installed via apt, such as arc-theme, materia-gtk-theme, papirus-icon-theme.
    • You can also download theme packages from websites like Gnome-Look.org and extract them to specific folders in your home directory:
      • GTK/Shell themes: ~/.themes
      • Icon themes: ~/.icons (If these folders don't exist, create them yourself.)
  • Applying themes:
    • GNOME: Requires the gnome-tweaks tool. In the "Appearance" section of Tweaks, you can set the cursor, icon, and "Legacy Applications" (GTK) themes. To change the Shell theme, you also need to install the User Themes GNOME extension.
    • KDE Plasma: Go to "System Settings" -> "Appearance". KDE provides very comprehensive theme management, allowing you to switch global themes with one click, or set application style, Plasma style, colors, icons, cursors, etc., individually.
    • Xfce: Go to "Settings" -> "Appearance" to set the style and icons. Go to "Settings" -> "Window Manager" to set the window borders.

Installing and switching dual graphics (NVIDIA/AMD) drivers in Debian

For laptops with both Intel/AMD integrated graphics and an NVIDIA dedicated GPU (Optimus technology), correctly configuring drivers and switching methods is crucial.

Solution:

1. Install the proprietary NVIDIA driver:

   • First, you must follow the tutorial below to Install NVIDIA drivers. The nvidia-driver package in Debian has built-in support for Prime technology.

2. Switching graphics modes:

   • After installing the driver, you will have a tool called prime-select.
   • Check the currently active GPU:

     sudo prime-select query

   • Switch to NVIDIA dedicated graphics mode (higher performance, more power consumption):

     sudo prime-select nvidia

   • Switch to Intel/AMD integrated graphics mode (more power-efficient):

     sudo prime-select intel
     # or sudo prime-select amd

   • You need to log out or reboot for the change to take effect.

3. On-Demand Rendering:

   • This is the most recommended mode currently. The system uses the integrated GPU by default to render the desktop, saving power. When you need to run a high-performance application (like a game or 3D modeling software), you can specify it to run on the NVIDIA dedicated GPU.
   • Switch to on-demand mode:

     sudo prime-select on-demand

     You also need to log out or reboot.
   • How to use: In on-demand mode, to run a program with the dedicated GPU, simply prefix the command with specific environment variables:

     # Example: run glxgears test program with NVIDIA dGPU
     __NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia glxgears

     For convenience, you can create desktop shortcuts or set an alias for frequently used programs. Many gaming platforms like Steam or Lutris handle this automatically.

How to install NVIDIA drivers on Debian

Installing the proprietary NVIDIA drivers on Debian is key to getting the best graphics performance. Do not download the .run file from the NVIDIA website to install, as this will conflict with the system's package manager and cause the driver to fail after a kernel update. Always use the nvidia-driver package from the Debian repositories.

Installation Steps:

1. Enable contrib and non-free repositories:

   • The NVIDIA driver is in the non-free repository. Edit /etc/apt/sources.list and ensure your source lines include contrib and non-free at the end (since Debian 12, the driver is in non-free-firmware and non-free, and some dependencies are in contrib).

     deb http://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware

2. Update and install essential tools:

   sudo apt update
   sudo apt install linux-headers-$(uname -r) build-essential

   linux-headers are required to build the kernel module. $(uname -r) automatically gets the version of the kernel you are currently running.

3. Install the driver:

   • Debian provides the nvidia-detect tool to help you identify your graphics card model and the recommended driver package.

     sudo apt install nvidia-detect
     nvidia-detect

     It will output a message like It is recommended to install the ... nvidia-driver package.
   • Based on the recommendation from nvidia-detect, install the corresponding driver package. For recent graphics cards, this is usually nvidia-driver.

     sudo apt install nvidia-driver firmware-misc-nonfree

     firmware-misc-nonfree contains some firmware required by NVIDIA cards.

4. Create an Xorg configuration file (optional but recommended):

   • Create a simple Xorg configuration file to ensure the NVIDIA driver is loaded.
   • Run sudo nano /etc/X11/xorg.conf.d/20-nvidia.conf and add the following content:

     Section "Device"
         Identifier "NVIDIA Card"
         Driver "nvidia"
         VendorName "NVIDIA Corporation"
     EndSection

5. Reboot:

   • You must reboot the computer for the new kernel module and driver to take effect.
   • After rebooting, you can run the nvidia-smi command. If it successfully outputs your graphics card information and driver version, congratulations, the driver is installed correctly!

What is the difference between Wayland and X11? How should I choose?

X11 (X Window System) and Wayland are the two main display server protocols on Linux. They are the underlying foundation of the graphical interface, responsible for managing windows, handling input, and rendering the screen.

• X11 (or X.Org Server)

  • History: Very old, created in 1984. It has been the de facto standard for graphical interfaces on Linux and Unix-like systems for decades.
  • Architecture: Uses a client-server model. The X Server is the core, responsible for interacting with hardware; various applications act as clients connecting to the server. This design was advanced for its time and supported network transparency (i.e., running a program on computer A and displaying it on computer B), but it also led to a complex and redundant architecture.
  • Pros:
    • Excellent compatibility: Almost all graphical applications support X11.
    • Mature features: Supports a wide range of tools for screen recording, screenshots, remote desktops, etc.
    • Full support for NVIDIA drivers.
  • Cons:
    • Outdated architecture: To implement modern desktop effects (like window animations), a separate compositor needs to run on top of the X Server, leading to a longer rendering path and lower efficiency.
    • Poor security: X11's design allows any client application to listen to keyboard input and window content of all other applications, posing a security risk.
    • Poor support for modern hardware like HiDPI displays and touchscreens, with complex configuration.

• Wayland

  • History: A more modern replacement, designed to fundamentally simplify the graphics stack.
  • Architecture: Wayland itself is just a protocol. The functions of a display server, compositor, and window manager are integrated into a single process called a "Wayland Compositor" (e.g., GNOME's Mutter, KDE's KWin). Applications communicate directly with the compositor.
  • Pros:
    • Simple and efficient architecture: Shorter rendering path, better performance and responsiveness, and reduced screen tearing.
    • Good security: Applications are isolated from each other, so one application cannot easily spy on the content or input of another.
    • Native support for modern features: Better support for HiDPI (different scaling factors for different monitors), touchscreens, gestures, etc.
  • Cons:
    • Compatibility is still catching up: Although major applications and toolkits (GTK, Qt) now support Wayland natively, some older applications or specific tools (like certain screen recording or remote desktop software) may need to run through a compatibility layer called XWayland, which can sometimes cause issues.
    • NVIDIA driver support used to be a pain point: NVIDIA has greatly improved its driver support for Wayland in recent years, but it may still not be as stable as X11 in some cases.

How should I choose?

• Using Wayland is recommended by default: Especially if you use the GNOME or KDE desktop environment and do not have a very old NVIDIA graphics card. The GNOME session in Debian 12 already defaults to Wayland. It provides a smoother, more secure, and more modern desktop experience.
• Switch back to X11 in the following cases:
  • You are experiencing unresolvable bugs with the proprietary NVIDIA driver under Wayland (e.g., flickering, performance issues).
  • You rely on a specific application that only works correctly under X11 (e.g., certain professional screen sharing or accessibility tools).
  • You are using a desktop environment that does not support Wayland (such as some versions of Cinnamon).

How to switch: On the login screen (GDM, LightDM, etc.), after entering your username, there is usually a gear icon or a dropdown menu next to the password field. Click it to choose between "GNOME" (which defaults to Wayland) and "GNOME on X.org".

Touchpad/touchscreen not working after Debian installation

These types of problems are usually caused by missing drivers or kernel modules.

Troubleshooting steps:

1. Install the xinput tool:

   sudo apt install xinput

   Run the xinput list command. If your touchpad or touchscreen device appears in the list (even if it's not working), it means the system has at least recognized the hardware. If it's not in the list at all, the problem is likely at a lower driver level.

2. Check kernel drivers:

   • Touchpad: Touchpads on modern laptops are usually handled by the libinput library. Make sure xserver-xorg-input-libinput is installed.

     sudo apt install xserver-xorg-input-libinput

   • Kernel log: Use the dmesg command to view kernel boot messages and grep to filter for keywords related to touchpads/touchscreens.

     dmesg | grep -i touch
     dmesg | grep -i synaptics
     dmesg | grep -i elan

     Check for any error messages or firmware loading failures.

3. Install firmware:

   • Like many other hardware devices, some touchpads/touchscreens also require non-free firmware to work. Trying to install general firmware packages might help.

   sudo apt install firmware-linux-nonfree

   This package contains a wide range of firmware files and might resolve the issue.

4. Synaptics Driver (for older laptops):

   • If you have an older laptop and libinput is not working well, you can try the older synaptics driver.

   sudo apt install xserver-xorg-input-synaptics

   You may need to configure X11 to prefer the synaptics driver over libinput.

How to configure HiDPI scaling on Debian

HiDPI (High Dots Per Inch) displays, often found on modern laptops and 4K/5K monitors, require scaling to make text and UI elements readable.

Configuration Methods by Desktop Environment:

• GNOME (Wayland recommended):

  • GNOME has excellent HiDPI support, especially on Wayland.
  • Go to "Settings" -> "Displays".
  • You can set a global "Scale" factor, which is usually an integer like 200%.
  • GNOME on Wayland also supports Fractional Scaling. You can enable it via a toggle switch, which will give you more granular scaling options like 125%, 150%, 175%.
  • For multi-monitor setups, Wayland allows you to set a different scaling factor for each display, which is a major advantage over X11.

• KDE Plasma (Wayland or X11):

  • KDE also has robust HiDPI support.
  • Go to "System Settings" -> "Display and Monitor" -> "Display Configuration".
  • You can set a global "Scale" factor. KDE supports both integer and fractional scaling on both X11 and Wayland.
  • Additionally, you can go to "Appearance" -> "Fonts" and force the font DPI, which can help in some applications.

• Xfce (more manual):

  • Xfce's HiDPI support is less integrated. You often need to configure several places.
  1. Window Scaling: Go to "Settings" -> "Appearance" -> "Settings" tab, set "Window Scaling" to 2x.
  2. Font DPI: On the same tab, under "Fonts", set a custom DPI, e.g., 192 (for 200% scaling).
  3. Window Manager: Go to "Settings" -> "Window Manager", select a theme that has a xhdpi or hdpi variant (e.g., Default-hdpi).
  4. Cursor Size: In ~/.Xresources, add the line Xcursor.size: 48 and run xrdb -merge ~/.Xresources.

How does the graphical login screen (Display Manager) work?

The graphical login screen is handled by a program called a Display Manager (DM). Its main jobs are:

1. Start the display server (X server or Wayland compositor).
2. Provide a graphical user interface for users to enter their username and password.
3. Authenticate the user.
4. Start the user's chosen desktop environment session (e.g., GNOME, KDE).

Debian allows you to have multiple desktop environments installed, and the DM is what lets you choose which one to start.

Common Display Managers on Debian:

• GDM (GNOME Display Manager): The default for the task-gnome-desktop. It's tightly integrated with GNOME.
• LightDM: A lightweight, fast, and highly themable display manager. It's the default for Xfce and MATE in Debian. It often uses a "greeter" theme like slick-greeter or gtk-greeter.
• SDDM (Simple Desktop Display Manager): The default for the task-kde-desktop. It's based on QML and is highly integrated with Plasma.

Changing the default Display Manager: If you have more than one DM installed, you can switch the default one by running:

sudo dpkg-reconfigure gdm3
# Or sddm, lightdm

A text-based dialog will appear, allowing you to choose which DM should be active.