6.3 KiB
KDE Plasma Installation and Revert Guide for reTerminal DM4
Device Information
- Model: Raspberry Pi Compute Module 4 (CM4)
- CPU: Cortex-A72 (4 cores)
- RAM: 8GB
- Current Desktop: LXDE with Openbox
- Display: 10-inch, 1280x800
Pre-Installation State
Current Desktop Packages
- libobrender32v5
- libobt2v5:arm64
- lxsession
- lxsession-data
- lxsession-logout
- openbox
- pcmanfm
Current Session Manager
- Default:
/usr/bin/startx-rpd(priority 90) - Available:
/usr/bin/lxsession(priority 49) - Available:
/usr/bin/openbox-session(priority 40) - Current mode: auto (points to startx-rpd)
Available Desktop Sessions
- lightdm-xsession.desktop
- openbox.desktop
- rpd-x.desktop
Installation Date
- Date: 2026-01-09
Installation Steps
Step 1: Update System
sudo apt-get update
sudo apt-get upgrade -y
Step 2: Install KDE Plasma
# Install KDE Plasma desktop (lightweight version)
sudo apt-get install -y kde-plasma-desktop
# Install on-screen keyboard for touchscreen
sudo apt-get install -y maliit-keyboard
# Install additional KDE utilities
sudo apt-get install -y kde-standard
Step 3: Configure Default Desktop
Option A: Switch at Login (Recommended - Safest)
- Log out of current session
- At login screen, click on the session/desktop selector (usually in top-right corner)
- Select "Plasma (X11)" or "plasmax11"
- Log in
Option B: Set as Default
# Set KDE as default desktop session
sudo update-alternatives --config x-session-manager
# Select: /usr/bin/startplasma-x11 (priority 40)
Note: KDE Plasma X11 session is available at /usr/share/xsessions/plasmax11.desktop
Step 4: Configure Touchscreen Settings
After logging into KDE:
-
Enable On-Screen Keyboard:
- System Settings > Input Devices > Virtual Keyboard
- Enable "Show on-screen keyboard when needed"
-
Adjust Touch Settings:
- System Settings > Input Devices > Touchpad/Touchscreen
- Adjust touch sensitivity
- Enable tap-to-click
-
UI Scaling for Touch:
- System Settings > Display and Monitor
- Set scale to 125% or 150% for better touch targets
-
Disable Heavy Effects (for better performance):
- System Settings > Workspace Behavior > Desktop Effects
- Disable resource-intensive effects
- Keep basic animations enabled
Step 5: Reboot
sudo reboot
Post-Installation Verification
After reboot, verify KDE is working:
echo $XDG_CURRENT_DESKTOP
# Should show: KDE or plasma
ps aux | grep -i plasma
# Should show KDE processes running
Cloud-Init (Automated Install)
For EMMC provisioning you can install KDE, set it as the default session, and enable touch options automatically using cloud-init. Use the example that includes KDE and touch:
- File:
emmc-provisioning/cloud-init/user-data-kiosk-username-ssh.example
It installs kde-plasma-desktop, maliit-keyboard, and xinput-calibrator; sets LightDM default session to Plasma (X11); writes KDE config for touch-friendly scaling and touch-point feedback; and autostarts the on-screen keyboard. Chromium kiosk and SSH are configured in the same example. Replace the password hash and use it as your cloud-init user-data when building the image.
Reverting to LXDE
Method 1: Switch at Login Screen (Easiest)
- Log out of current session
- At the login screen, click on the session/desktop selector (usually top-right)
- Select "Openbox" or "RPD-X" session
- Log in
Method 1b: Use Revert Script
A revert script is provided: revert-to-lxde.sh
# Copy script to device and run
./revert-to-lxde.sh
Method 2: Change Default Session
# Set LXDE as default
sudo update-alternatives --config x-session-manager
# Select LXDE option (usually /usr/bin/startlxde or similar)
Method 3: Remove KDE (Complete Revert)
If you want to completely remove KDE:
# Remove KDE packages
sudo apt-get remove --purge kde-plasma-desktop kde-standard
sudo apt-get autoremove -y
sudo apt-get autoclean
# Restore LXDE as default
sudo update-alternatives --config x-session-manager
# Select LXDE
# Reboot
sudo reboot
Method 4: Reinstall LXDE (if removed)
If LXDE was accidentally removed:
sudo apt-get update
sudo apt-get install --reinstall lxde
sudo update-alternatives --config x-session-manager
Troubleshooting
KDE Won't Start
# Check if KDE is installed
dpkg -l | grep kde-plasma
# Check available sessions
ls /usr/share/xsessions/
# Try starting KDE manually
startplasma-wayland
# or
startplasma-x11
Performance Issues
- Disable desktop effects in System Settings
- Reduce animation duration
- Use X11 instead of Wayland (if Wayland is causing issues)
Touchscreen Not Working
# Check touchscreen device
xinput list
# Calibrate touchscreen
sudo apt-get install xinput-calibrator
xinput_calibrator
Chromium Autostart Issues
Your existing Chromium autostart configuration should work with KDE. If it doesn't, check:
cat ~/.config/autostart/chromium-kiosk.desktop
Performance Notes
- Expected RAM Usage: 400-800MB for KDE Plasma
- Expected CPU Usage: Low to moderate (Cortex-A72 handles it well)
- Boot Time: Slightly longer than LXDE (~10-15 seconds more)
Files Modified/Created
/usr/share/xsessions/- Desktop session files~/.config/plasma-org.kde.plasma.desktop-appletsrc- KDE panel configuration~/.config/kwinrc- Window manager settings~/.config/plasmarc- Plasma settings
Backup Before Installation
To create a backup of current desktop settings:
# Backup current desktop configuration
mkdir -p ~/desktop-backup
cp -r ~/.config/lx* ~/desktop-backup/ 2>/dev/null
cp -r ~/.config/openbox ~/desktop-backup/ 2>/dev/null
Rollback Checklist
If you need to revert:
- Switch session at login screen (easiest)
- Change default session via update-alternatives
- Remove KDE packages if needed
- Verify LXDE is working
- Check Chromium autostart still works
- Verify touchscreen calibration
Support
If you encounter issues:
- Check system logs:
journalctl -xe - Check X/Wayland logs:
~/.xsession-errors - Verify packages:
dpkg -l | grep kde - Check available sessions:
ls /usr/share/xsessions/