From 0fce0749b5463497f7d8c42fa4d889d4c6cff3e2 Mon Sep 17 00:00:00 2001
From: Bruce Toll <4109762+tollb@users.noreply.github.com>
Date: Fri, 21 Apr 2023 07:56:00 -0400
Subject: [PATCH] nixos/udev: Fix hwdb conflict handling; build with
 systemdb-hwdb

Switch to systemdb-hwdb to build the udev hwdb.bin, as "udevadm hwdb" is
deprecated. This fixes an issue where the order of conflicting keys is
not respected.  The systemd-hwdb command creates a newer format (v3) of
hwdb.bin that respects the ordering of duplicate keys, with later
values replacing earlier occurrences.

A release note is included, as some mappings may be affected.
---
 nixos/doc/manual/release-notes/rl-2305.section.md | 2 ++
 nixos/modules/services/hardware/udev.nix          | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/nixos/doc/manual/release-notes/rl-2305.section.md b/nixos/doc/manual/release-notes/rl-2305.section.md
index 601109ccee5..0e8c8dd9b80 100644
--- a/nixos/doc/manual/release-notes/rl-2305.section.md
+++ b/nixos/doc/manual/release-notes/rl-2305.section.md
@@ -166,6 +166,8 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - The option `i18n.inputMethod.fcitx5.enableRimeData` has been removed. Default RIME data is now included in `fcitx5-rime` by default, and can be customized using `fcitx5-rime.override { rimeDataPkgs = [ pkgs.rime-data, package2, ... ]; }`
 
+- The udev hwdb.bin file is now built with systemd-hwdb rather than the [deprecated "udevadm hwdb"](https://github.com/systemd/systemd/pull/25714). This may impact mappings where the same key is defined in multiple matching entries. The updated behavior will select the latest definition in case of conflict. In general, this should be a positive change, as the hwdb source files are designed with this ordering in mind. As an example, the mapping of the HP Dev One keyboard scan code for "mute mic" is corrected by this update. This change may impact users who have worked-around previously incorrect mappings.
+
 - Kime has been updated from 2.5.6 to 3.0.2 and the `i18n.inputMethod.kime.config` option has been removed. Users should use `daemonModules`, `iconColor`, and `extraConfig` options under `i18n.inputMethod.kime` instead.
 
 - `tut` has been updated from 1.0.34 to 2.0.0, and now uses the TOML format for the configuration file instead of INI. Additional information can be found [here](https://github.com/RasmusLindroth/tut/releases/tag/2.0.0).
diff --git a/nixos/modules/services/hardware/udev.nix b/nixos/modules/services/hardware/udev.nix
index 95c2a4fc5c3..94406b60b29 100644
--- a/nixos/modules/services/hardware/udev.nix
+++ b/nixos/modules/services/hardware/udev.nix
@@ -160,7 +160,7 @@ let
 
       echo "Generating hwdb database..."
       # hwdb --update doesn't return error code even on errors!
-      res="$(${pkgs.buildPackages.udev}/bin/udevadm hwdb --update --root=$(pwd) 2>&1)"
+      res="$(${pkgs.buildPackages.systemd}/bin/systemd-hwdb --root=$(pwd) update 2>&1)"
       echo "$res"
       [ -z "$(echo "$res" | egrep '^Error')" ]
       mv etc/udev/hwdb.bin $out