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Server: Don't disable Wayland; Use Display :1024
On modern Linux distributions, GDM runs Xwayland on Display :1024 if WaylandEnable=true (the default), and it runs Xorg on Display :0 if WaylandEnable=false. Referring to aa5ff87 and #94, in 2019 I observed that it was necessary on RHEL 8 and Fedora 27-28 to add/uncomment WaylandEnable=false in order for VirtualGL's greeter autostart script to work. However, that is apparently no longer necessary. In 2025, using Display :1024 seems to work fine on RHEL 7-10, Ubuntu 16-24, Fedora 40-42, and openSUSE 15. (In fact, it is necessary on RHEL 10, since GDM no longer allows Wayland to be disabled. That is what prompted this change.)
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‎ChangeLog.md‎

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@@ -12,6 +12,12 @@ in the VirtualGL User's Guide for more information.
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enabling quad-buffered stereo, even if the requirements for quad-buffered
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stereo had been met.
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3. On Wayland-enabled Linux systems running GDM, `vglserver_config` no longer
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disables the ability to log in locally with a Wayland session. Instead,
17+
`vglrun` automatically sets `VGL_DISPLAY` to `:1024` if `VGL_DISPLAY` is unset,
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X Display :1024 exists, and X Display :0 does not exist. This allows VirtualGL
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to use the GDM greeter's Xwayland instance as a 3D X server.
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3.1.3
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=====

‎doc/advancedconfig.txt‎

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@@ -119,21 +119,26 @@ previous method:
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| Summary | __''{d}''__ = the X display/screen or EGL device to use for 3D \
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rendering |
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| Image Transports | All |
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| Default Value | '':0'' |
122+
| Default Value | '':0'' or '':1024'' |
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#OPT: hiCol=first
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Description :: If the VirtualGL server has multiple GPUs, then you can use
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this option to specify which GPU should be used for 3D rendering. For
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instance, setting ''VGL_DISPLAY'' to (or invoking ''vglrun -d'' with)
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'':0.1'' would cause VirtualGL to use the GLX back end and redirect all of
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the OpenGL rendering from the 3D application to a GPU attached to Screen 1 on
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X display :0. Setting ''VGL_DISPLAY'' to (or invoking ''vglrun -d'' with)
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X Display :0. Setting ''VGL_DISPLAY'' to (or invoking ''vglrun -d'' with)
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a DRI device path (such as ''/dev/dri/card0'') or an EGL device ID (such as
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''egl0'') would cause VirtualGL to use the EGL back end and redirect all of
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the OpenGL rendering from the 3D application to the specified EGL device.
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''/opt/VirtualGL/bin/eglinfo -e'' lists all valid EGL device IDs and their
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associated DRI device paths.
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!!! ''vglrun'' automatically sets ''VGL_DISPLAY'' to '':1024'' if
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''VGL_DISPLAY'' is unset, X Display :1024 exists, and X Display :0 does not
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exist. This allows VirtualGL to use the GDM greeter's Xwayland instance as a
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3D X server.
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| Environment Variable | {pcode: VGL_EGLLIB = __{l}__ } |
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| Summary | __''{l}''__ = the location of an alternate EGL library |
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| Image Transports | All |

‎doc/index.html‎

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@@ -3,7 +3,7 @@
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<head>
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<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
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<meta name="language" content="en">
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<meta name="date" content="2025-07-01T12:15:57">
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<meta name="date" content="2025-10-07T13:56:21">
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<meta name="generator" content="deplate.rb 0.8.5">
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<title>User&rsquo;s Guide for VirtualGL 3.1.4</title>
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<link rel="start" href="index.html" title="Frontpage">
@@ -921,10 +921,6 @@ <h2 id="hd006001">6.1&nbsp;Initial System Configuration</h2>
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and 3D X server at boot time. This is the default with most modern
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Linux and Unix distributions.</p>
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<div class="important"><p class="important">
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On Wayland-enabled Linux machines running GDM, configuring the machine for use with the GLX back end will disable the ability to log in locally with a Wayland session. In general, logging in locally once the machine has been configured for use with the GLX back end is discouraged, as this could disrupt VirtualGL&rsquo;s connection to the 3D X server and thus cause OpenGL applications running with VirtualGL to abort or freeze.
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</p></div>
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<p>3. Accelerated OpenGL is working properly in the 3D X server.</p>
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<ul class="Itemize">
@@ -969,8 +965,10 @@ <h2 id="hd006002">6.2&nbsp;GLX Back End: Granting Access to the 3D X Server</h2>
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need to use the GLX back end. Unless you fully trust the users to whom
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you are granting this access, then you should avoid logging in locally
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to the 3D X server (particularly as root) unless absolutely necessary.
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(Logging in locally to the 3D X server is discouraged anyhow, for
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reasons explained in the previous section.)</p>
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(In general, logging in locally once the machine has been configured for
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use with the GLX back end is discouraged, as this could disrupt
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VirtualGL&rsquo;s connection to the 3D X server and thus cause OpenGL
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applications running with VirtualGL to abort or freeze.)</p>
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<p>This section will explain how to configure a VirtualGL server such that
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selected users can use the GLX back end, even if the server is sitting
@@ -1166,27 +1164,26 @@ <h3 id="hd006002001">6.2.1&nbsp;Sanity Check</h3>
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<dl class="Description">
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<dt class="Description-1 Description">If you restricted 3D X server access to <code>vglusers</code></dt>
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<dd class="Description-1 Description">
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<pre class="verbatim">
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xauth&nbsp;merge&nbsp;/etc/opt/VirtualGL/vgl_xauth_key
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xdpyinfo&nbsp;-display&nbsp;:0
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/opt/VirtualGL/bin/glxinfo&nbsp;-display&nbsp;:0&nbsp;-c
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</pre>
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</dd>
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</dl>
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<pre class="verbatim">xauth merge /etc/opt/VirtualGL/vgl_xauth_key
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xdpyinfo -display :<em>n</em>
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/opt/VirtualGL/bin/glxinfo -display :<em>n</em> -c</pre>
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<dl class="Description">
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<dt class="Description-1 Description">If you did not restrict 3D X server access</dt>
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<dd class="Description-1 Description">
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<pre class="verbatim">
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xdpyinfo&nbsp;-display&nbsp;:0
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/opt/VirtualGL/bin/glxinfo&nbsp;-display&nbsp;:0&nbsp;-c
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</pre>
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</dd>
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</dl>
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<p>Both commands should output a list of visuals and should complete with
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no errors. If you chose to disable the <code>XTEST</code> extension,
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then check the output of the <code>xdpyinfo</code> command to verify
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that <code>XTEST</code> does not show up in the list of extensions.</p>
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<pre class="verbatim">xdpyinfo -display :<em>n</em>
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/opt/VirtualGL/bin/glxinfo -display :<em>n</em> -c</pre>
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<p>(where <em><code>n</code></em> is the display number of the 3D X
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server.) Both commands should output a list of visuals and should
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complete with no errors. If you chose to disable the <code>XTEST</code>
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extension, then check the output of the <code>xdpyinfo</code> command to
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verify that <code>XTEST</code> does not show up in the list of
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extensions.</p>
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11911188
<p>You should also examine the output of the <code>glxinfo</code> command
11921189
to ensure that at least one of the visuals is 24-bit or 32-bit TrueColor
@@ -3103,7 +3100,7 @@ <h2 id="hd0018001">18.1&nbsp;Faker Settings</h2>
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</tr>
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<tr class="standard">
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<td class="high standard">Default Value</td>
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<td class="standard"><code>:0</code></td>
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<td class="standard"><code>:0</code> or <code>:1024</code></td>
31073104
</tr>
31083105
</table>
31093106
</div>
@@ -3118,13 +3115,16 @@ <h2 id="hd0018001">18.1&nbsp;Faker Settings</h2>
31183115
<code>vglrun&nbsp;-d</code> with) <code>:0.1</code> would cause
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VirtualGL to use the GLX back end and redirect all of the OpenGL
31203117
rendering from the 3D application to a GPU attached to Screen 1 on X
3121-
display :0. Setting <code>VGL_DISPLAY</code> to (or invoking
3118+
Display :0. Setting <code>VGL_DISPLAY</code> to (or invoking
31223119
<code>vglrun&nbsp;-d</code> with) a DRI device path (such as
31233120
<code>/dev/dri/card0</code>) or an EGL device ID (such as
31243121
<code>egl0</code>) would cause VirtualGL to use the EGL back end and
31253122
redirect all of the OpenGL rendering from the 3D application to the
31263123
specified EGL device. <code>/opt/VirtualGL/bin/eglinfo&nbsp;-e</code>
31273124
lists all valid EGL device IDs and their associated DRI device paths.
3125+
<div class="important"><p class="important">
3126+
<code>vglrun</code> automatically sets <code>VGL_DISPLAY</code> to <code>:1024</code> if <code>VGL_DISPLAY</code> is unset, X Display :1024 exists, and X Display :0 does not exist. This allows VirtualGL to use the GDM greeter&rsquo;s Xwayland instance as a 3D X server.
3127+
</p></div>
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</dd>
31293129
</dl>
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‎doc/unixconfig.txt‎

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@@ -21,13 +21,6 @@ LightDM) installed and has been configured to start the display manager and 3D
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X server at boot time. This is the default with most modern Linux and Unix
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distributions.
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24-
!!! On Wayland-enabled Linux machines running GDM, configuring the machine
25-
for use with the GLX back end will disable the ability to log in locally with
26-
a Wayland session. In general, logging in locally once the machine has been
27-
configured for use with the GLX back end is discouraged, as this could
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disrupt VirtualGL's connection to the 3D X server and thus cause OpenGL
29-
applications running with VirtualGL to abort or freeze.
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3. Accelerated OpenGL is working properly in the 3D X server.
3225
* If the 3D X server is not headless, then this can be verified by logging
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into the X server locally and running ''glxinfo''.
@@ -60,8 +53,10 @@ disallow access to the GPU. Thus, it is necessary to grant full, trusted
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access to the 3D X server for any users that will need to use the GLX back end.
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Unless you fully trust the users to whom you are granting this access, then
6255
you should avoid logging in locally to the 3D X server (particularly as root)
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unless absolutely necessary. (Logging in locally to the 3D X server is
64-
discouraged anyhow, for reasons explained in the previous section.)
56+
unless absolutely necessary. (In general, logging in locally once the machine
57+
has been configured for use with the GLX back end is discouraged, as this could
58+
disrupt VirtualGL's connection to the 3D X server and thus cause OpenGL
59+
applications running with VirtualGL to abort or freeze.)
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This section will explain how to configure a VirtualGL server such that
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selected users can use the GLX back end, even if the server is sitting at the
@@ -206,22 +201,23 @@ end, log out of the server, log back into the server using SSH, and execute the
206201
following commands in the SSH session:
207202

208203
If you restricted 3D X server access to ''vglusers'' :: {:}
209-
#Verb <<---
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xauth merge /etc/opt/VirtualGL/vgl_xauth_key
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xdpyinfo -display :0
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/opt/VirtualGL/bin/glxinfo -display :0 -c
213-
---
204+
#Pverb <<---
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xauth merge /etc/opt/VirtualGL/vgl_xauth_key
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xdpyinfo -display :__n__
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/opt/VirtualGL/bin/glxinfo -display :__n__ -c
208+
---
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215210
If you did not restrict 3D X server access :: {:}
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#Verb <<---
217-
xdpyinfo -display :0
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/opt/VirtualGL/bin/glxinfo -display :0 -c
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---
220-
221-
Both commands should output a list of visuals and should complete with no
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errors. If you chose to disable the ''XTEST'' extension, then check the output
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of the ''xdpyinfo'' command to verify that ''XTEST'' does not show up in the
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list of extensions.
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#Pverb <<---
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xdpyinfo -display :__n__
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/opt/VirtualGL/bin/glxinfo -display :__n__ -c
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---
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216+
(where __''n''__ is the display number of the 3D X server.) Both commands
217+
should output a list of visuals and should complete with no errors. If you
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chose to disable the ''XTEST'' extension, then check the output of the
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''xdpyinfo'' command to verify that ''XTEST'' does not show up in the list of
220+
extensions.
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226222
You should also examine the output of the ''glxinfo'' command to ensure that at
227223
least one of the visuals is 24-bit or 32-bit TrueColor and has Pbuffer support.

‎server/vglrun.in‎

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@@ -2,7 +2,7 @@
22

33
# Copyright (C)2004 Landmark Graphics Corporation
44
# Copyright (C)2005 Sun Microsystems, Inc.
5-
# Copyright (C)2009-2016, 2018-2019, 2021, 2024 D. R. Commander
5+
# Copyright (C)2009-2016, 2018-2019, 2021, 2024-2025 D. R. Commander
66
#
77
# This library is free software and may be redistributed and/or modified under
88
# the terms of the wxWindows Library License, Version 3.1 or (at your option)
@@ -41,7 +41,7 @@ usage()
4141
echo " library."
4242
echo
4343
echo "-d <d> : <d> = the X display/screen or EGL device to use for 3D rendering"
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echo " [default = :0]"
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echo " [default = :0 or :1024]"
4545
echo
4646
echo "-fps <f> : Limit image transport frame rate to <f> frames/sec"
4747
echo
@@ -193,12 +193,20 @@ else
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if [ ! -z "$SSH_IP" -a -z "$VGL_CLIENT" -a -z "$RRCLIENT" ]; then
194194
VGL_CLIENT=$SSH_IP
195195
export VGL_CLIENT
196-
echo "[VGL] NOTICE: Automatically setting VGL_CLIENT environment variable to"
196+
echo "[VGL] NOTICE: Automatically setting the VGL_CLIENT environment variable to"
197197
echo "[VGL] $SSH_IP, the IP address of your SSH client."
198198
fi
199199
fi
200200
fi
201201

202+
if [ -z "$VGL_DISPLAY" -a ! -e /tmp/.X11-unix/X0 -a \
203+
-e /tmp/.X11-unix/X1024 ]; then
204+
echo "[VGL] NOTICE: Automatically setting the VGL_DISPLAY environment variable to"
205+
echo "[VGL] :1024, the X display number of the GDM greeter's Xwayland instance."
206+
VGL_DISPLAY=:1024
207+
export VGL_DISPLAY
208+
fi
209+
202210
# This is so we can launch both 32-bit and 64-bit executables using the same
203211
# script.
204212
if [ -x "$MYPATH/.vglrun.vars64" ]; then

‎server/vglserver_config‎

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@@ -20,7 +20,6 @@ RMMODNEEDED=0
2020
NVIDIADRMNEEDED=0
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UNATTENDED=0
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SELINUX=0
23-
WAYLAND=0
2423
BACKEND=glx
2524

2625
GID=
@@ -281,22 +280,6 @@ disallowgdmtcp()
281280
commentline $1 "DisallowTCP.*=.*"
282281
}
283282

284-
disablewaylandgdm()
285-
{
286-
backup $1
287-
echo ... Disabling Wayland in $1 ...
288-
grep -q "WaylandEnable.*=.*false" $1 && (
289-
uncommentline $1 "WaylandEnable.*=.*false"
290-
) || (
291-
grep -q "WaylandEnable" $1 && (
292-
replaceline $1 WaylandEnable "WaylandEnable=false"
293-
) || (
294-
removeline $1 WaylandEnable
295-
addtoconf $1 "daemon" "daemon" WaylandEnable=false
296-
)
297-
)
298-
}
299-
300283
setdripermissions()
301284
{
302285
if [ -z "$1" ]; then
@@ -579,37 +562,6 @@ checkselinux()
579562
fi
580563
}
581564

582-
checkwayland()
583-
{
584-
which Xwayland >/dev/null 2>&1 || return 0
585-
if [ -f /etc/systemd/system/display-manager.service ]; then
586-
DM=`grep ExecStart=\/usr /etc/systemd/system/display-manager.service | sed 's/.*\///g'`
587-
if [ ! "$DM" = "gdm" -a ! "$DM" = "gdm3" ]; then
588-
return 0
589-
fi
590-
elif [ -f /etc/alternatives/default-displaymanager ]; then
591-
DM=`grep DISPLAYMANAGER=\/usr /etc/alternatives/default-displaymanager | sed 's/.*\///g'`
592-
if [ ! "$DM" = "gdm" ]; then
593-
return 0
594-
fi
595-
else
596-
return 0
597-
fi
598-
WAYLAND=1
599-
echo
600-
echo WARNING: Configuring this server for use with VirtualGL will disable the
601-
echo ability to log in locally with a Wayland session.
602-
if [ $UNATTENDED = 0 ]; then
603-
ynprompt "Continue?"
604-
if [ ! "$?" = "1" ]; then
605-
return 1
606-
fi
607-
else
608-
echo
609-
fi
610-
return 0
611-
}
612-
613565
unconfigglx()
614566
{
615567
if [ -d /etc/opt/VirtualGL ]; then
@@ -793,8 +745,6 @@ configegl()
793745

794746
configglx()
795747
{
796-
checkwayland || return
797-
798748
if [ $UNATTENDED = 0 ]; then
799749
ynprompt "Restrict 3D X server access to vglusers group (recommended)?"
800750
if [ $? = 1 ]; then VGLUSERSONLY=1; else VGLUSERSONLY=0; fi
@@ -916,8 +866,8 @@ EOF
916866
/etc/X11/gdm/custom.conf \
917867
/etc/gdm3/custom.conf \
918868
/etc/gdm3/daemon.conf; do
919-
if [ -f $file -a ! -h $file -a $WAYLAND = 1 ]; then
920-
disablewaylandgdm $file
869+
if [ -f $file -a ! -h $file ]; then
870+
commentline $file "WaylandEnable.*=.*false"
921871
fi
922872
done
923873

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