# lightdm is probably not needed. The server can run the multi-user target without a GUI.
systemctl set-default multi-user.target

# We need both 32bit and 64bit virtualGL if the application is 32bit.
rpm -e VirtualGL --allmatches
yum -y install VirtualGL.x86_64  VirtualGL.i386

##
# install the nvidia driver from elrepo
# Remove ocl-id because it conflicts with the nvidia driver because of OpenCL
yum -y remove ocl-icd.x86_64

yum -y install yum-plugin-fastestmirror nvidia-detect
nvidia-detect | grep -qs kmod && yum -y install $(nvidia-detect)

# reboot for the nvidia drives to detect everything.
reboot

# Grab the bus ID for the nvidia card. this should similar to "PCI:1:0:0". lspci can provide the same info, but the format is slighly different. nvidia-xconfig shuold provide a format that is compatible with "Xorg -isolateDevice"
bus=$(nvidia-xconfig  --query-gpu-info|grep PCI|awk '{print $4}')

systemctl isolate multi-user.target

# Remove any previous config file runs
rm -f /root/xorg.conf.new  

# move any primar DISPLAY=":0 config out of the way
mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak

Xorg :1 -configure -isolateDevice $bus

# xorg written as /root/xorg.conf.new
# this seems to fail sometimes. Just use nvidia-xconfig and move /etc/X/xorg.conf to /etc/X/xorg.1.conf

# Run "Xorg :1 -config /root/xorg.conf.new" and check for errors. Ctrl-C to cancel
mv -f /root/xorg.conf.new /etc/X11/xorg.1.conf

# Add the magic nvidia bits to xorg.conf
nvidia-xconfig -a --allow-empty-initial-configuration --busid=$bus --use-display-device=none --virtual=1920x1200 -c /etc/X11/xorg.1.conf

#mv /etc/X11/xorg.conf /etc/X11/xorg.1.conf
### Set up a systemd service to manage Xorg Display :1

### begin headlessx.service ##### Just copy and paste into bash
cat > /etc/systemd/system/headlessx@.service <<EOF
[Unit]
Description=VirtualGL Headless X server on display %I
After=multi-user.target

[Service]
Type=simple
ExecStart=/bin/bash -c "Xorg :%i  -listen tcp -config /etc/X11/xorg.%i.conf"
Restart=on-failure

[Install]
WantedBy=multi-user.target
EOF
### end headlessx.service #####

systemctl daemon-reload
systemctl enable headlessx@1
systemctl restart headlessx@1


# configure virtualGL to restrict users to all all users (DANGER). disable XTEST
/opt/VirtualGL/bin/vglserver_config -config -s +f -t

# refresh X display permissions as changed by vglserver_config
systemctl isolate multi-user.target
systemctl stop headlessx@1
rmmod nvidia_drm nvidia_modeset nvidia
systemctl start headlessx@1

cat > /etc/profile.d/virtualgl.sh <<EOF
# Configure the default DISPLAY for VirtualGL vglrun
export VGL_DISPLAY=':1'
EOF

reboot

# check xorg log for errors:
# Ignore error (EE) Failed to load module "glxservernvidia" (module does not exist, 0)
grep EE /var/log/Xorg.1.log


######################### end instructions ##############################

##### additional troubleshooting steps/notes #####

######## example commands below for running VirtualGL as a normal user. This is intended for use with StarNet FastX.
VGL_DISPLAY=:1 vglrun -c proxy +v /opt/VirtualGL/bin/glxspheres64