From 8d24105642111f441fc8e08edeb1a06ac559762d Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Wed, 10 Jan 2018 00:11:25 -0500
Subject: [PATCH] Document the GDK_VULKAN env var

This was not documented at all yet.
---
 docs/reference/gtk/running.sgml | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/docs/reference/gtk/running.sgml b/docs/reference/gtk/running.sgml
index 3d042a01a1..b717d717c2 100644
--- a/docs/reference/gtk/running.sgml
+++ b/docs/reference/gtk/running.sgml
@@ -459,6 +459,28 @@ nevertheless.
   </para>
 </formalpara>
 
+<formalpara>
+  <title><envar>GDK_VULKAN</envar></title>
+
+  <para>
+    This variable can be set to a list of options that influence various aspects
+    of the Vulkan support in GTK+.
+  <variablelist>
+    <varlistentry>
+      <term>disable</term>
+      <listitem><para>Disable Vulkan support</para></listitem>
+    </varlistentry>
+    <varlistentry>
+      <term>validate </term>
+      <listitem><para>Enable the Vulkan validation layer</para></listitem>
+    </varlistentry>
+  </variablelist>
+  The special value <literal>all</literal> can be used to turn on all
+  options. The special value <literal>help</literal> can be used
+  to obtain a list of all supported options.
+  </para>
+</formalpara>
+
 <formalpara>
   <title><envar>GTK_CSD</envar></title>
 
-- 
2.30.2