Add NixOS dual-configuration setup (dev and gaming profiles)

Co-authored-by: ragusa-it <196988693+ragusa-it@users.noreply.github.com>

README.md

@@ -1 +1,207 @@
-# nixos
+# NixOS Dual-Configuration Setup
+
+A NixOS system with **two fully isolated configurations**:
+
+1. **Dev** - Latest stable kernel, web development tooling (Docker, Node.js, direnv)
+2. **Gaming** - Zen kernel, Steam, Lutris, performance tools
+
+Both share a common base: MangoWC (Wayland compositor) + Noctalia Shell, AMD RDNA 4 GPU support, and a shared `/home` directory with mutable dotfiles.
+
+## Target Hardware
+
+| Component | Model | Notes |
+|-----------|-------|-------|
+| CPU | AMD Ryzen 7 5700G | Zen 3, iGPU available |
+| GPU | AMD RX 9060 XT | RDNA 4, requires Kernel 6.14+, Mesa 25.0+ |
+| Motherboard | MSI B550 Tomahawk | Excellent IOMMU groups |
+
+## Directory Structure
+
+```
+nixos-config/
+├── flake.nix                           # Main flake definition
+├── flake.lock                          # Auto-generated after first build
+├── hosts/
+│   └── <hostname>/
+│       └── hardware-configuration.nix  # Copy from /etc/nixos/
+└── modules/
+    ├── common.nix                      # Shared configuration
+    ├── dev.nix                         # Development profile
+    └── gaming.nix                      # Gaming profile
+```
+
+## Prerequisites
+
+1. NixOS installed (minimal install is fine)
+2. Flakes enabled in existing config or via: `nix-shell -p nixFlakes`
+3. Know your hostname, username, timezone, and locale
+
+## Quick Setup
+
+### 1. Clone and Prepare
+
+```bash
+# Clone this repo to your config directory
+git clone <this-repo> ~/nixos-config
+cd ~/nixos-config
+
+# Replace the placeholder hardware-configuration.nix with your actual one
+cp /etc/nixos/hardware-configuration.nix hosts/<hostname>/
+```
+
+### 2. Replace Placeholders
+
+Edit the following files and replace these placeholders:
+
+| Placeholder | Example Value | Files |
+|-------------|---------------|-------|
+| `<hostname>` | `desktop` | `flake.nix`, `modules/common.nix` |
+| `<username>` | `john` | `modules/common.nix`, `modules/dev.nix`, `modules/gaming.nix` |
+| `<timezone>` | `America/New_York` | `modules/common.nix` |
+| `<locale>` | `en_US.UTF-8` | `modules/common.nix` |
+
+Also rename `hosts/hostname/` to match your actual hostname.
+
+### 3. Stage Files in Git
+
+```bash
+cd ~/nixos-config
+git add .
+```
+
+### 4. Verify Flake
+
+```bash
+nix flake check
+nix flake show
+```
+
+### 5. Build and Switch
+
+```bash
+# Build and switch to dev config as main system profile
+sudo nixos-rebuild switch --flake .#dev
+
+# Build gaming config as separate boot profile
+sudo nixos-rebuild boot --profile-name gaming --flake .#gaming
+```
+
+### 6. Reboot and Verify
+
+Boot menu should show:
+- `NixOS (dev)` - Default boot
+- `NixOS (gaming, zen)` - Gaming profile
+
+## Updating
+
+**IMPORTANT:** Always update both profiles together to avoid kernel/Mesa version drift:
+
+```bash
+cd ~/nixos-config
+git add .
+sudo nixos-rebuild switch --flake .#dev
+sudo nixos-rebuild boot --profile-name gaming --flake .#gaming
+```
+
+To update flake inputs:
+
+```bash
+nix flake update
+git add flake.lock
+sudo nixos-rebuild switch --flake .#dev
+sudo nixos-rebuild boot --profile-name gaming --flake .#gaming
+```
+
+## Configuration Summary
+
+| Config | Kernel | Key Features |
+|--------|--------|--------------|
+| `dev` | Latest | Docker, Node.js, direnv, dev CLI tools |
+| `gaming` | Zen | Steam, Lutris, MangoHUD, Gamemode, CoreCtrl |
+| **Shared** | - | MangoWC, Noctalia, AMD GPU, PipeWire, Firefox |
+
+## Post-Installation
+
+### Change Password
+
+```bash
+passwd
+```
+
+### Setup MangoWC
+
+```bash
+mkdir -p ~/.config/mango
+cp /etc/mango/config.conf ~/.config/mango/config.conf
+
+# Create autostart script
+cat > ~/.config/mango/autostart.sh << 'EOF'
+#!/bin/bash
+qs -c noctalia-shell &
+EOF
+chmod +x ~/.config/mango/autostart.sh
+```
+
+Add to `~/.config/mango/config.conf`:
+```
+exec-once="~/.config/mango/autostart.sh"
+```
+
+### Auto-start MangoWC from TTY
+
+Add to `~/.bash_profile` or `~/.zprofile`:
+```bash
+if [[ -z $WAYLAND_DISPLAY ]] && [[ $(tty) == /dev/tty1 ]]; then
+    exec mango
+fi
+```
+
+## GPU Verification
+
+```bash
+# Verify firmware loaded
+dmesg | grep -i "amdgpu" | grep -i "firmware"
+
+# Check GPU detected
+lspci | grep VGA
+
+# Verify Vulkan
+vulkaninfo | head -30
+
+# Check ray tracing support
+vulkaninfo | grep VK_KHR_ray_tracing_pipeline
+
+# Verify OpenCL
+clinfo | head -20
+```
+
+## Troubleshooting
+
+### Flake can't find files
+```bash
+git add .  # Flakes require files to be tracked by git
+```
+
+### MangoWC doesn't start
+```bash
+systemctl status seatd
+groups  # Ensure user is in 'seat' group
+```
+
+### RDNA 4 black screen
+```bash
+dmesg | grep -i "amdgpu" | grep -i "firmware"
+uname -r  # Should be 6.14+
+```
+
+### Steam doesn't launch
+Ensure `hardware.graphics.enable32Bit = true;` in common.nix.
+
+### Games won't launch
+```bash
+cat /proc/sys/vm/max_map_count  # Should be 2147483642 on gaming profile
+```
+
+## License
+
+MIT