From 413f779bc048b5daf3267ff86a6ff38712774148 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Tue, 2 Apr 2024 18:14:25 +0200
Subject: [PATCH 1/2] nixos/udev: don't create modprobe config if modprobe is
 disabled

---
 nixos/modules/services/hardware/udev.nix | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/nixos/modules/services/hardware/udev.nix b/nixos/modules/services/hardware/udev.nix
index 670b9087f110..e442f7c669dd 100644
--- a/nixos/modules/services/hardware/udev.nix
+++ b/nixos/modules/services/hardware/udev.nix
@@ -401,17 +401,19 @@ in
       }))
     ];
 
-    environment.etc =
-      {
-        "udev/rules.d".source = udevRulesFor {
-          name = "udev-rules";
-          udevPackages = cfg.packages;
-          systemd = config.systemd.package;
-          binPackages = cfg.packages;
-          inherit udevPath udev;
-        };
-        "udev/hwdb.bin".source = hwdbBin;
+    environment.etc = {
+      "udev/rules.d".source = udevRulesFor {
+        name = "udev-rules";
+        udevPackages = cfg.packages;
+        systemd = config.systemd.package;
+        binPackages = cfg.packages;
+        inherit udevPath udev;
       };
+      "udev/hwdb.bin".source = hwdbBin;
+    } // lib.optionalAttrs config.boot.modprobeConfig.enable {
+      # We don't place this into `extraModprobeConfig` so that stage-1 ramdisk doesn't bloat.
+      "modprobe.d/firmware.conf".text = "options firmware_class path=${config.hardware.firmware}/lib/firmware";
+    };
 
     system.requiredKernelConfig = with config.lib.kernelConfig; [
       (isEnabled "UNIX")
@@ -419,8 +421,6 @@ in
       (isYes "NET")
     ];
 
-    # We don't place this into `extraModprobeConfig` so that stage-1 ramdisk doesn't bloat.
-    environment.etc."modprobe.d/firmware.conf".text = "options firmware_class path=${config.hardware.firmware}/lib/firmware";
 
     system.activationScripts.udevd =
       ''

From 4677729c56baa64814a0e0cff4cf999cf543e343 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Tue, 2 Apr 2024 18:14:50 +0200
Subject: [PATCH 2/2] nixos/udev: only load firmware from udev when the nixos
 kernel is used

This is not the case for eg. NixOS in WSL
---
 nixos/modules/services/hardware/udev.nix | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/nixos/modules/services/hardware/udev.nix b/nixos/modules/services/hardware/udev.nix
index e442f7c669dd..913babd94782 100644
--- a/nixos/modules/services/hardware/udev.nix
+++ b/nixos/modules/services/hardware/udev.nix
@@ -421,19 +421,17 @@ in
       (isYes "NET")
     ];
 
+    system.activationScripts.udevd = lib.mkIf config.boot.kernel.enable ''
+      # The deprecated hotplug uevent helper is not used anymore
+      if [ -e /proc/sys/kernel/hotplug ]; then
+        echo "" > /proc/sys/kernel/hotplug
+      fi
 
-    system.activationScripts.udevd =
-      ''
-        # The deprecated hotplug uevent helper is not used anymore
-        if [ -e /proc/sys/kernel/hotplug ]; then
-          echo "" > /proc/sys/kernel/hotplug
-        fi
-
-        # Allow the kernel to find our firmware.
-        if [ -e /sys/module/firmware_class/parameters/path ]; then
-          echo -n "${config.hardware.firmware}/lib/firmware" > /sys/module/firmware_class/parameters/path
-        fi
-      '';
+      # Allow the kernel to find our firmware.
+      if [ -e /sys/module/firmware_class/parameters/path ]; then
+        echo -n "${config.hardware.firmware}/lib/firmware" > /sys/module/firmware_class/parameters/path
+      fi
+    '';
 
     systemd.services.systemd-udevd =
       { restartTriggers = cfg.packages;