X server: Log to the journal instead of /var/log/X.0.log

This ensures that "journalctl -u display-manager" does what you would
expect in 2016. However, the main reason is to ensure that our VM
tests show the output of the X server.

A slight problem is that with KDE user switching, messages from the
various X servers end up in the same place. However, that's an
improvement over the previous situation, where the second X server
would overwrite the /var/log/X.0.log of the first. (This was caused by
the fact that we were passing a hard-coded value for -logfile.)

1 files changed, 3 insertions, 1 deletions

diff --git a/nixos/modules/services/x11/xserver.nix b/nixos/modules/services/x11/xserver.nix
index 4f65ed72d36e..82d3e31e2a01 100644
--- a/nixos/modules/services/x11/xserver.nix
+++ b/nixos/modules/services/x11/xserver.nix
@@ -520,6 +520,7 @@ in
         serviceConfig = {
           Restart = "always";
           RestartSec = "200ms";
+          SyslogIdentifier = "display-manager";
         };
       };
 
@@ -527,10 +528,11 @@ in
       [ "-terminate"
         "-config ${configFile}"
         "-xkbdir" "${cfg.xkbDir}"
+        # Log at the default verbosity level to stderr rather than /var/log/X.*.log.
+        "-verbose" "3" "-logfile" "/dev/null"
       ] ++ optional (cfg.display != null) ":${toString cfg.display}"
         ++ optional (cfg.tty     != null) "vt${toString cfg.tty}"
         ++ optional (cfg.dpi     != null) "-dpi ${toString cfg.dpi}"
-        ++ optionals (cfg.display != null) [ "-logfile" "/var/log/X.${toString cfg.display}.log" ]
         ++ optional (!cfg.enableTCP) "-nolisten tcp";
 
     services.xserver.modules =