KVM Switch: Mac ↔ Nobara

Hardware

Monitor: Dell U3821DW (USB-C to Mac, HDMI 2 to Nobara)
Keyboard: Logitech MX Keys S
Mouse: Logitech MX Master 4
Bolt #1: Connected to Nobara (Channel 2)
Bolt #2: Connected to Mac via monitor USB hub (Channel 3)

Switching Behavior

Direction	Monitor	Peripherals
Nobara → Mac	Auto (DDC)	Auto (HID++)
Mac → Nobara	Auto (DDC)	Manual Easy-Switch

Channel Setup

Channel	Connection	Computer
2	Bolt #1	Nobara
3	Bolt #2	Mac

Nobara Setup

1. Install dependencies

sudo dnf install ddcutil
sudo usermod -aG i2c $USER
# Reboot required for i2c group

2. Install hidapitester

mkdir -p ~/bin
curl -sL https://github.com/todbot/hidapitester/releases/latest/download/hidapitester-linux-amd64.zip -o /tmp/hidapitester.zip
unzip -o /tmp/hidapitester.zip -d ~/bin/
chmod +x ~/bin/hidapitester

3. Udev rule for Bolt

echo 'SUBSYSTEM=="usb", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="c548", MODE="0666"' | sudo tee /etc/udev/rules.d/99-logitech-bolt.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

4. Copy script

mkdir -p ~/scripts
cp to_mac.sh ~/scripts/
chmod +x ~/scripts/to_mac.sh

5. Keyboard shortcut (Ctrl+Shift+Up)

Settings → Keyboard → Custom Shortcuts:

Name: KVM to Mac
Command: /home/USER/scripts/to_mac.sh
Shortcut: Ctrl+Shift+Up

Mac Setup

1. Install m1ddc

brew install m1ddc

2. Copy script

mkdir -p ~/scripts
cp to_nobara.sh ~/scripts/
chmod +x ~/scripts/to_nobara.sh

3. Usage

~/scripts/to_nobara.sh
# Then press Easy-Switch on keyboard/mouse to Channel 2

DDC Input Codes (Dell U3821DW)

Input	Code
HDMI 2	18
USB-C	27