Logitech MX Master 4 on Fedora Linux – My Final Solaar Configuration

The MX Master 4 is a fantastic productivity mouse, but its advanced features (custom buttons, horizontal scroll with the thumb wheel, SmartShift, Action Ring, etc.) are not fully supported out of the box on Fedora with Wayland.

Solaar is the best open-source tool for configuring Logitech devices on Linux. It allows us to customize buttons, create rules, and unlock most of the mouse’s potential.

After many hours of testing and tweaking, here is my stable daily configuration.

1. Installing Solaar

sudo dnf install solaar

2. udev Rule (Recommended)

This rule improves stability and permissions for custom rules on Wayland:

sudo tee /etc/udev/rules.d/44-logitech-unify-permissions.rules << 'EOF'
# Solaar - Logitech MX Master 4
KERNEL=="uinput", SUBSYSTEM=="misc", TAG+="uaccess", OPTIONS+="static_node=uinput"

ACTION=="remove", GOTO="solaar_end"
SUBSYSTEM!="hidraw", GOTO="solaar_end"

# USB-connected Logitech receivers
ATTRS{idVendor}=="046d", GOTO="solaar_apply"

# Bluetooth-connected Logitech devices (MX Master 4)
KERNELS=="0005:046D:*", GOTO="solaar_apply"

GOTO="solaar_end"

LABEL="solaar_apply"
TAG+="uaccess"

LABEL="solaar_end"
EOF

Apply the rules:

sudo udevadm control --reload-rules && sudo udevadm trigger

Recommendation: Reboot your system after creating this file.

3. Solaar GUI Settings

Open Solaar, select your MX Master 4 on the left side, and configure the following:

4. Final Button Configuration

Tip: Leave the small button behind the scroll wheel as SmartShift (toggles Ratcheted / Free Spin).

The Thumb Wheel (horizontal scroll) is configured via a custom rule in the rules.yaml file.

5. Custom Rules (rules.yaml)

The custom rules are stored in:

~/.config/solaar/rules.yaml

First, make a backup of the current file (if it exists).

cp ~/.config/solaar/rules.yaml ~/.config/solaar/rules.yaml.backup 2>/dev/null || true

Create the new rules file

cat > ~/.config/solaar/rules.yaml << 'EOF'
%YAML 1.3
---
- Key: [Haptic, pressed]
  KeyPress:
    - [Control_L, c]
    - click
...
---
- Key: [Mouse Gesture Button, pressed]
  KeyPress:
    - [Control_L, v]
    - click
...
---
- Rule:
    - Test: thumb_wheel_up
    - MouseScroll: [2, 0]
- Rule:
    - Test: thumb_wheel_down
    - MouseScroll: [-2, 0]
...
EOF

After creating the file, restart Solaar or log out and back in.

Note: You can adjust scroll speed by changing the values 2 and -2. Only integers are accepted (e.g. [3, 0] and [-3, 0] for faster scrolling).

Tip: Always keep a backup of your rules.yaml before doing a clean Fedora upgrade.