啓用Ubuntu的間接渲染Indirect Render(Test on Ubuntu 18.04)

安全起見，正式發佈的Ubuntu Desktop OS默認關閉了GLX的Indirect Render。修改以下幾項配置，可以啓用Indirect Render。
1. /usr/share/gdm/gdm.schemas

    <schema>
      <key>security/DisallowTCP</key>
      <signature>b</signature>
      <default>false</default>
    </schema>

2. /etc/X11/xinit/xserverrc

#!/bin/sh

#exec /usr/bin/X -nolisten tcp +iglx "$@"
exec /usr/bin/X -listen tcp +iglx "$@"

3. /etc/X11/xorg.conf

Section "ServerFlags"
    Option "AllowIndirectGLX" "on"
    Option "IndirectGLX" "on"
EndSection

4. /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf

[Seat:*]
# Dump core
xserver-command=X -core +iglx

驗證方法：glxinfo -i
確認direct rendering: No

$ glxinfo -i
name of display: :0
display: :0  screen: 0
direct rendering: No (-i specified)
server glx vendor string: NVIDIA Corporation
server glx version string: 1.4