From 11f165a094d7d3a5e4cc0c39ff9e36ef1548edeb Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Wed, 25 Feb 2026 09:59:29 -0800
Subject: [PATCH 1/2] nixos/xserver: inform xserver about externally configured
 drivers

This commit adds a new (internal) option to let the xserver module know
about externally configured drivers (i.e., drivers that this module
should treat as "configured" but otherwise ignore). Without this, the
xserver module will think the driver hasn't been configured and throw an
error.

This commit also expands the documentation to explain when to choose
`drivers` versus `externallyConfiguredDrivers`.
---
 nixos/modules/services/x11/xserver.nix | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index fd52b0023d94..b33e6f4ddda1 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -497,7 +497,25 @@ in
         internal = true;
         description = ''
           A list of attribute sets specifying drivers to be loaded by
-          the X11 server.
+          the X11 server. This module will create a Device section in
+          the Xorg config for every driver listed here, along with a
+          Screen section if the driver's {option}`display` attribute is
+          `true`. If such configuration sections should not be created,
+          use {options}`services.xserver.externallyConfiguredDrivers`
+          instead.
+
+          Users should not add drivers to this option but should instead
+          add drivers to {option}`services.xserver.videoDrivers`.
+        '';
+      };
+
+      externallyConfiguredDrivers = mkOption {
+        type = types.listOf types.str;
+        internal = true;
+        description = ''
+          A list of externally configured drivers (by name). Modules that
+          manually configure their drivers should add said drivers to this
+          list to let this module know that the driver has been configured.
         '';
       };
 
@@ -865,7 +883,9 @@ in
       }
     ]
     ++ map (driver: {
-      assertion = builtins.elem driver (builtins.catAttrs "name" cfg.drivers);
+      assertion = builtins.elem driver (
+        (builtins.catAttrs "name" cfg.drivers) ++ cfg.externallyConfiguredDrivers
+      );
       message = "Unknown X11 driver ‘${driver}’ specified in `services.xserver.videoDrivers`.";
     }) cfg.videoDrivers;
 

From 71f94c224a0f1bf22121b75fe95087174fbc4e28 Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Wed, 25 Feb 2026 10:03:05 -0800
Subject: [PATCH 2/2] nixos/hardware.displaylink: add displaylink to
 xserver.externallyConfiguredDrivers

Add "displaylink" to `services.xserver.externallyConfiguredDrivers`  to
let the xserver module know that said driver has already been configured
out-of-band.

Fixes #491861
---
 nixos/modules/hardware/video/displaylink.nix | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/nixos/modules/hardware/video/displaylink.nix b/nixos/modules/hardware/video/displaylink.nix
index d8284e85ae45..bee931da1806 100644
--- a/nixos/modules/hardware/video/displaylink.nix
+++ b/nixos/modules/hardware/video/displaylink.nix
@@ -23,6 +23,8 @@ in
     boot.extraModulePackages = [ evdi ];
     boot.kernelModules = [ "evdi" ];
 
+    services.xserver.externallyConfiguredDrivers = [ "displaylink" ];
+
     environment.etc."X11/xorg.conf.d/40-displaylink.conf".text = ''
       Section "OutputClass"
         Identifier  "DisplayLink"