Update RTL8125 driver to 9.018.00

systems/x86_64-linux/drivebystation-nix/configuration.nix

@@ -12,12 +12,10 @@
   imports = [
     ./tigervnc.nix
     ./hardware/hardware-configuration.nix
+    ./hardware/realtek-r8125.nix
   ];
 
 
-  # Use the default kernel maintained by the stable nixpkgs release.
-  boot.kernelPackages = pkgs.linuxPackages;
-
   # Bootloader.
   # boot.loader.systemd-boot.enable = true; # managed by lanzaboote
   boot.loader.efi.canTouchEfiVariables = true;

systems/x86_64-linux/drivebystation-nix/hardware/realtek-r8125.nix

@@ -0,0 +1,22 @@
+{ pkgs, ... }:
+
+{
+  # Keep the vendor driver tied to this host's selected kernel, including its
+  # build dependencies and module installation path supplied by nixpkgs.
+  boot.kernelPackages = pkgs.linuxPackages.extend (_final: prev: {
+    r8125 = prev.r8125.overrideAttrs {
+      version = "9.018.00";
+      # The mirror's top-level wrapper overrides BASEDIR with /lib/modules.
+      # Build in src directly so nixpkgs' kernel path reaches kbuild.
+      buildFlags = [ "-C" "src" "modules" ];
+      # Realtek's release mirrored by the DKMS maintainer. Pin the source rather
+      # than running the vendor installer or following a mutable branch.
+      src = pkgs.fetchFromGitHub {
+        owner = "awesometic";
+        repo = "realtek-r8125-dkms";
+        rev = "9a152bf920334aead090d2fb4d91f67a84923123"; # 9.018.00-1
+        hash = "sha256-yeQsyraNrms1Txm7ZAKeiPfF0tfN6WSHUo5DnvfFosw=";
+      };
+    };
+  });
+}