From 693a31ab7b53de423d4ed87f35a6a43604d02039 Mon Sep 17 00:00:00 2001
From: Atemu <atemu.main@gmail.com>
Date: Sat, 15 Feb 2020 22:53:56 +0100
Subject: [PATCH] nixos/xserver: make logFile configurable

It makes sense for it to be /dev/null for all the displayManagers but startx,
it needs a different logFile configuration.
---
 nixos/modules/services/x11/xserver.nix | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index 9e971671c47..eb8c4c17e98 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -518,6 +518,19 @@ in
         '';
       };
 
+      logFile = mkOption {
+        type = types.nullOr types.str;
+        default = "/dev/null";
+        example = "/var/log/Xorg.0.log";
+        description = ''
+          Controls the file Xorg logs to.
+
+          The default of <literal>/dev/null</literal> is set so that systemd services (like <literal>displayManagers</literal>) only log to the journal and don't create their own log files.
+
+          Setting this to <literal>null</literal> will not pass the <literal>-logfile</literal> argument to Xorg which allows it to log to its default logfile locations instead (see <literal>man Xorg</literal>). You probably only want this behaviour when running Xorg manually (e.g. via <literal>startx</literal>).
+        '';
+      };
+
       verbose = mkOption {
         type = types.nullOr types.int;
         default = 3;
@@ -692,11 +705,10 @@ in
     services.xserver.displayManager.xserverArgs =
       [ "-config ${configFile}"
         "-xkbdir" "${cfg.xkbDir}"
-        # Log at the default verbosity level to stderr rather than /var/log/X.*.log.
-         "-logfile" "/dev/null"
       ] ++ optional (cfg.display != null) ":${toString cfg.display}"
         ++ optional (cfg.tty     != null) "vt${toString cfg.tty}"
         ++ optional (cfg.dpi     != null) "-dpi ${toString cfg.dpi}"
+        ++ optional (cfg.logFile != null) "-logfile ${toString cfg.logFile}"
         ++ optional (cfg.verbose != null) "-verbose ${toString cfg.verbose}"
         ++ optional (!cfg.enableTCP) "-nolisten tcp"
         ++ optional (cfg.autoRepeatDelay != null) "-ardelay ${toString cfg.autoRepeatDelay}"