From Looking Glass
Revision as of 00:28, 10 October 2019 by Techfreak (talk | contribs) (Switching <code> blocks to <syntaxhighlight > block and embedded Windows Host Application Page)
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Looking Glass Client

This guide will step you through building the looking glass client on Debian based systems from source, before you attempt to do this you should have a basic understanding how to use the shell.

Building the Application

Installing Build Dependencies

  • binutils-dev
  • cmake
  • fonts-freefont-ttf
  • libsdl2-dev
  • libsdl2-ttf-dev
  • libspice-protocol-dev
  • libfontconfig1-dev
  • libx11-dev
  • nettle-dev
Debian (and maybe Ubuntu)
apt-get install binutils-dev cmake fonts-freefont-ttf libsdl2-dev libsdl2-ttf-dev libspice-protocol-dev libfontconfig1-dev libx11-dev nettle-dev
Fedora 29+
yum install make cmake binutils-devel SDL2-devel SDL2_ttf-devel nettle-devel spice-protocol fontconfig-devel libX11-devel egl-wayland-devel wayland-devel mesa-libGLU-devel mesa-libGLES-devel mesa-libGL-devel mesa-libEGL-devel
OpenSuSE Leap 15.0+
zypper install make cmake binutils-devel libSDL2-devel libSDL2_ttf-devel libnettle-devel nettle spice-protocol-devel fontconfig-devel libX11-devel libconfig-devel libwayland-egl-devel


Either visit the site at Looking Glass Download Page

Or pull the lastest using the git command.

git clone


If you downloaded the file via the web link then you should have a 'zip' file. Simply unzip and cd into the new directory. If you used 'git' then cd into the 'LookingGlass' directory.

mkdir build
cd build
cmake ../
The most common compile error is related to backtrace support this can be disabled by adding the following option to the cmake command. -DENABLE_BACKTRACE=0.

Should this all go well you should be left with the file looking-glass-client. Before you run the client you will first need to configure either Libvirt or Qemu (whichever you prefer) and then setup the Windows side service.

libvirt Configuration

This article assumes you already have a fully functional libvirt VM with PCI Passthrough working on a dedicated monitor. If you do not please ensure this is configured before you proceed.

If you are using QEMU directly, this does not apply to you.

Add the following to the libvirt machine configuration inside the 'devices' section by running "virsh edit VM" where VM is the name of your virtual machine.

<shmem name='looking-glass'>
  <model type='ivshmem-plain'/>
  <size unit='M'>32</size>

The memory size (show as 32 in the example above may need to be adjusted as per Determining Memory section.

Qemu Commands

Add the following to the commands to your QEMU command line, adjusting the bus to suit your particular configuration:

-device ivshmem-plain,memdev=ivshmem,bus=pcie.0 \
-object memory-backend-file,id=ivshmem,share=on,mem-path=/dev/shm/looking-glass,size=32M

The memory size (show as 32 in the example above may need to be adjusted as per Determining Memory section.

Determining Memory

You will need to adjust the memory size to a value that is suitable for your desired maximum resolution using the following formula:

width x height x 4 x 2 = total bytes
total bytes / 1024 / 1024 = total megabytes + 2

For example, for a resolution of 1920x1080 (1080p)

1920 x 1080 x 4 x 2 = 16,588,800 bytes
16,588,800 / 1024 / 1024 = 15.82 MB + 2 = 17.82

You must round this value up to the nearest power of two, which with the above example would be 32MB

It is suggested that you create the shared memory file before starting the VM with the appropriate permissions for your system, this only needs to be done once at boot time, for example (this is a sample script only, do not use this without altering it for your requirements):

touch /dev/shm/looking-glass && chown user:kvm /dev/shm/looking-glass && chmod 660 /dev/shm/looking-glass

Looking Glass Service (Windows)

Installing the IVSHMEM Driver

Windows will not prompt for a driver for the IVSHMEM device, instead it will use a default null (do nothing) driver for the device. To install the IVSHMEM driver you will need to go into device manager and update the driver for the device "PCI standard RAM Controller" under the "System Devices" node.

A signed Windows 10 driver can be obtained from Red Hat for this device from the below address:

Please note that you must obtain version 0.1.161 or later

Using the Windows Host Application

Windows Host Application

Running the Client

The client command is the binary file: looking-glass-client. This command should run after the Windows Host Application has started.

For an updated list of arguments visit:

Common options include '-s' for disabling spice, '-S' for disabling the screen saver, '-F' to automatically enter full screen and '-k' to disable the UPS/FPS rate.