Installation

Client

The Looking Glass Client receives frames from the Host to display on your screen. It also handles input, and can optionally share the system clipboard with your guest OS through Spice.

First you must build the client from source code, see Building.

libvirt Configuration

This article assumes you already have a fully functional libvirt domain with PCI passthrough working on a dedicated monitor.

If you use virt-manager, this guide also applies to you, since virt-manager uses libvirt as its back-end.

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

Add the following to your 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>
</shmem>

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

Spice Server

If you would like to use Spice to give you keyboard and mouse input along with clipboard sync support, make sure you have a <graphics type='spice'> device, then:

• Find your <video> device, and set <model type='none'/>

  • If you can’t find it, make sure you have a <graphics> device, save and edit again

  • On older libvirt versions, just disable the device in Windows Device Manager

• Remove the <input type='tablet'/> device, if you have one

• Create an <input type='mouse'/> device, if you don’t already have one

• Create an <input type='keyboard' bus='virtio'/> device to improve keyboard usage

  • This requires the vioinput driver from virtio-win to be installed in the guest

If you want clipboard synchronization please see Clipboard Synchronization

AppArmor

For libvirt versions before 5.10.0, if you are using AppArmor, you need to add permissions for QEMU to access the shared memory file. This can be done by adding the following to /etc/apparmor.d/local/abstractions/libvirt-qemu:

/dev/shm/looking-glass rw,

then, restart AppArmor.

sudo systemctl restart apparmor

Memballoon

The VirtIO memballoon device enables the host to dynamically reclaim memory from your VM by growing the balloon inside the guest, reserving reclaimed memory. Libvirt adds this device to guests by default.

However, this device causes major performance issues with VFIO passthrough setups, and should be disabled.

Find the <memballoon> tag and set its type to none:

<memballoon model="none"/>

QEMU Commands

If you are using libvirt/virt-manager, then this does not apply to you.

Add the following to the commands to your QEMU command line, adjusting the bus parameter 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 (shown as 32M 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 be suitable for your desired maximum resolution, with the following formula:

width x height x 4 x 2 = total bytes

total bytes / 1024 / 1024 = total megabytes + 10

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 + 10 = 25.82 MB

You must round this value up to the nearest power of two, which for the provided example is 32MB.

Shared Memory File Permissions

The shared memory file used by IVSHMEM is found in /dev/shm/looking-glass. By default, it is owned by QEMU, and does not give read/write permissions to your user, which are required for Looking Glass to run properly.

You can use systemd-tmpfiles to create the file before running your VM, granting the necessary permissions which allow Looking Glass to use the file properly.

Create a new file /etc/tmpfiles.d/10-looking-glass.conf, and populate it with the following:

#Type Path               Mode UID  GID Age Argument

f /dev/shm/looking-glass 0660 user kvm -

Change UID to the user name you will run Looking Glass with, usually your own.

Clipboard Synchronization

Looking Glass can synchronize the clipboard between the host and guest using the SPICE guest agent.

1. Install the SPICE guest tools from https://www.spice-space.org/download.html#windows-binaries.

2. Configure your VM to enable the SPICE guest agent:

• QEMU

-device virtio-serial-pci \
-chardev spicevmc,id=vdagent,name=vdagent \
-device virtserialport,chardev=vdagent,name=com.redhat.spice.0

• libvirt

<channel type="spicevmc">
  <target type="virtio" name="com.redhat.spice.0"/>
  <address type="virtio-serial" controller="0" bus="0" port="1"/>
</channel>
<!-- No need to add a VirtIO Serial device, it will be added automatically -->

Usage

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

You may run the client directly from the build directory. Alternatively, to install the client for all users, you can run

make install

To install for the local user only, run

cmake -DCMAKE_INSTALL_PREFIX=~/.local .. && make install

Default Key Bindings

By default, Looking Glass uses the Scroll Lock key as the escape key for commands, as well as the input capture mode toggle; this can be changed using the -m switch if you desire a different key. Below are a list of current key bindings:

Command	Description
ScrLk	Toggle capture mode
ScrLk + Q	Quit
ScrLk + R	Rotate the output clockwise by 90° increments
ScrLk + T	Show frame timing information
ScrLk + I	Spice keyboard & mouse enable toggle
ScrLk + O	Toggle overlay
ScrLk + D	FPS display toggle
ScrLk + F	Full screen toggle
ScrLk + V	Video stream toggle
ScrLk + N	Toggle night vision mode
ScrLk + F1	Send Ctrl + Alt + F1 to the guest
ScrLk + F2	Send Ctrl + Alt + F2 to the guest
ScrLk + F3	Send Ctrl + Alt + F3 to the guest
ScrLk + F4	Send Ctrl + Alt + F4 to the guest
ScrLk + F5	Send Ctrl + Alt + F5 to the guest
ScrLk + F6	Send Ctrl + Alt + F6 to the guest
ScrLk + F7	Send Ctrl + Alt + F7 to the guest
ScrLk + F8	Send Ctrl + Alt + F8 to the guest
ScrLk + F9	Send Ctrl + Alt + F9 to the guest
ScrLk + F10	Send Ctrl + Alt + F10 to the guest
ScrLk + F11	Send Ctrl + Alt + F11 to the guest
ScrLk + F12	Send Ctrl + Alt + F12 to the guest
ScrLk + Insert	Increase mouse sensitivity in capture mode
ScrLk + Del	Decrease mouse sensitivity in capture mode
ScrLk + LWin	Send LWin to the guest
ScrLk + RWin	Send RWin to the guest

You can also find this list at any time by holding down Scroll Lock.

Command Line Options

A full list of command line options is available with the --help or -h options.

Example: looking-glass-client --help

Common options include -s for disabling spice, -S for disabling the screen saver, and -F to automatically enter full screen.

Options may be provided with a short form, if available, or long form. Boolean options may be specified without a parameter to toggle their state.

Examples:

• looking-glass-client -F (short)

• looking-glass-client win:fullScreen (long)

• looking-glass-client -f /dev/shm/my-lg-shmem (short with parameter)

• looking-glass-client app:shmFile=/dev/shm/my-lg-shmem (long with parameter)

Configuration Files

By default, Looking Glass will load config files from the following locations:

• /etc/looking-glass-client.ini

• ~/.looking-glass-client.ini

• $XDG_CONFIG_HOME/looking-glass/client.ini (usually ~/.config/looking-glass/client.ini)

All config files are loaded in order. Duplicate entries override earlier ones. This means you can set a system-wide configuration in /etc/looking-glass-client.ini, and override specific options for just your user in ~/.looking-glass-client.ini, which is overlayed on top of the system-wide configuration.

When first launched, the Looking-Glass client will create the folder $XDG_CONFIG_HOME/looking-glass/ if it does not yet exist.

The format of config files is the commonly known INI format, for example:

[win]
fullScreen=yes

[egl]
nvGain=1

Command line arguments will override any options loaded from config files.

Overlay Mode

The Overlay Mode lets you configure various runtime options for Looking Glass. These include:

• EGL filters

• Performance metrics options

• Debug frame damage display

(see Configuration Widget)

You can also reposition and resize enabled widgets, like the FPS/UPS Display, and Performance Metrics.

Enter and exit Overlay Mode with ScrLk + O. ESC can also be used to exit. (see Default Key Bindings)

Modifications done to widgets in Overlay Mode are stored in $XDG_CONFIG_HOME/looking-glass/imgui.ini. Please do not manually edit this file while Looking Glass is running, as your changes may be discarded.

Configuration Widget

The Configuration Widget is accessible through the Overlay Mode. The widget has multiple tabs that allow setting a variety of modes and parameters for Looking Glass at runtime.

Settings tab

• Performance Metrics: A toggle for the Performance Metrics Widget. Multiple graphs are available, and they will stack vertically.

• EGL: Modify EGL features, such as the algorithm used for scaling, and night vision mode.

Changes in the Settings tab are not persistent, and will change back to their default values when the client is restarted.

EGL Filters tab

The EGL Filters tab contains options for toggling, configuring, and ordering post-processing filters. Each filter can be expanded to open its settings. Filters can also be re-ordered by dragging them up or down. Filters are applied from top to bottom, keep this in mind when ordering them, e.g applying CAS before FSR might have different results than the reverse. Users are encouraged to experiment with the order and parameters to achieve optimal results. The currently available filters include:

• Downscaler: Filter for downscaling the host resolution. Can be used to undo poor upscaling on the VM to better utilize AMD FSR (see below). The filter has a pixel-size setting that is used to set the effective downscaling ratio, and a configurable interpolation algorithm.

• AMD FidelityFX Super Resolution (FSR): Spatial upscaling filter that works on low resolution frames from the guest VM and intelligently upscales to a higher resolution. The filter sharpness is tunable, and displays the equivalent AMD quality mode based on the resolution difference.

• AMD FidelityFX Contrast Adaptive Sharpening (CAS): Filter that increases visual quality by applying a sharpening algorithm to the video. CAS can sometimes restore detail lost in a typical upscaling application. Has adjustable sharpness setting.

The filter settings and order can be saved to presets so that it can be restored at a later time. As filter settings are usually application specific, multiple presets can be defined for each case scenario. To save a preset, click on “Save preset as…” and enter a preset name. Presets are loaded by selecting them in the “Preset name” pull down. Presets are persistent and are stored on disk at $XDG_CONFIG_HOME/looking-glass/presets.

Warning

Please refrain from modifying any files under the presets folder. Those files are meant to be modified only by the Looking-Glass client.

Note

Although presets are persistent, the client will not remember which preset was used last session, so a preset needs to be recalled once the client starts.

Full Command Line Options

The following is a complete list of options accepted by this application

Long	Short	Value	Description
app:configFile	-C	NULL	A file to read additional configuration from
app:renderer	-g	auto	Specify the renderer to use
app:license	-l	no	Show the license for this application and then terminate
app:cursorPollInterval		1000	How often to check for a cursor update in microseconds
app:framePollInterval		1000	How often to check for a frame update in microseconds
app:allowDMA		yes	Allow direct DMA transfers if supported (see README.md in the module dir)
app:shmFile	-f	/dev/shm/looking-glass	The path to the shared memory file, or the name of the kvmfr device to use, e.g. kvmfr0

Long	Short	Value	Description
win:title		Looking Glass (client)	The window title
win:position		center	Initial window position at startup
win:size		1024x768	Initial window size at startup
win:autoResize	-a	no	Auto resize the window to the guest
win:allowResize	-n	yes	Allow the window to be manually resized
win:keepAspect	-r	yes	Maintain the correct aspect ratio
win:forceAspect		yes	Force the window to maintain the aspect ratio
win:dontUpscale		no	Never try to upscale the window
win:shrinkOnUpscale		no	Limit the window dimensions when dontUpscale is enabled
win:borderless	-d	no	Borderless mode
win:fullScreen	-F	no	Launch in fullscreen borderless mode
win:maximize	-T	no	Launch window maximized
win:minimizeOnFocusLoss		no	Minimize window on focus loss
win:fpsMin	-K	-1	Frame rate minimum (0 = disable - not recommended, -1 = auto detect)
win:ignoreQuit	-Q	no	Ignore requests to quit (i.e. Alt+F4)
win:noScreensaver	-S	no	Prevent the screensaver from starting
win:autoScreensaver		no	Prevent the screensaver from starting when guest requests it
win:alerts	-q	yes	Show on screen alert messages
win:quickSplash		no	Skip fading out the splash screen when a connection is established
win:rotate		0	Rotate the displayed image (0, 90, 180, 270)
win:uiFont		DejaVu Sans Mono	The font to use when rendering on-screen UI
win:uiSize		14	The font size to use when rendering on-screen UI
win:jitRender		no	Enable just-in-time rendering
win:showFPS	-k	no	Enable the FPS & UPS display

Long	Short	Value	Description
input:grabKeyboard	-G	yes	Grab the keyboard in capture mode
input:grabKeyboardOnFocus		no	Grab the keyboard when focused
input:releaseKeysOnFocusLoss		yes	On focus loss, send key up events to guest for all held keys
input:escapeKey	-m	70 = KEY_SCROLLLOCK	Specify the escape key, see <linux/input-event-codes.h> for valid values
input:ignoreWindowsKeys		no	Do not pass events for the windows keys to the guest
input:hideCursor	-M	yes	Hide the local mouse cursor
input:mouseSens		0	Initial mouse sensitivity when in capture mode (-9 to 9)
input:mouseSmoothing		yes	Apply simple mouse smoothing when rawMouse is not in use (helps reduce aliasing)
input:rawMouse		no	Use RAW mouse input when in capture mode (good for gaming)
input:mouseRedraw		yes	Mouse movements trigger redraws (ignores FPS minimum)
input:autoCapture		no	Try to keep the mouse captured when needed
input:captureOnly		no	Only enable input via SPICE if in capture mode
input:helpMenuDelay		200	Show help menu after holding down the escape key for this many milliseconds

Long	Short	Value	Description
spice:enable	-s	yes	Enable the built in SPICE client for input and/or clipboard support
spice:host	-c	127.0.0.1	The SPICE server host or UNIX socket
spice:port	-p	5900	The SPICE server port (0 = unix socket)
spice:input		yes	Use SPICE to send keyboard and mouse input events to the guest
spice:clipboard		yes	Use SPICE to synchronize the clipboard contents with the guest
spice:clipboardToVM		yes	Allow the clipboard to be synchronized TO the VM
spice:clipboardToLocal		yes	Allow the clipboard to be synchronized FROM the VM
spice:scaleCursor	-j	yes	Scale cursor input position to screen size when up/down scaled
spice:captureOnStart		no	Capture mouse and keyboard on start
spice:alwaysShowCursor		no	Always show host cursor
spice:showCursorDot		yes	Use a “dot” cursor when the window does not have focus

Long	Short	Value	Description
egl:vsync		no	Enable vsync
egl:doubleBuffer		no	Enable double buffering
egl:multisample		yes	Enable Multisampling
egl:nvGainMax		1	The maximum night vision gain
egl:nvGain		0	The initial night vision gain at startup
egl:cbMode		0	Color Blind Mode (0 = Off, 1 = Protanope, 2 = Deuteranope, 3 = Tritanope)
egl:scale		0	Set the scale algorithm (0 = auto, 1 = nearest, 2 = linear)
egl:debug		no	Enable debug output
egl:noBufferAge		no	Disable partial rendering based on buffer age
egl:noSwapDamage		no	Disable swapping with damage

Long	Short	Value	Description
opengl:mipmap		yes	Enable mipmapping
opengl:vsync		no	Enable vsync
opengl:preventBuffer		yes	Prevent the driver from buffering frames
opengl:amdPinnedMem		yes	Use GL_AMD_pinned_memory if it is available

Long	Short	Value	Description
wayland:warpSupport		yes	Enable cursor warping
wayland:fractionScale		yes	Enable fractional scale

Host

The Looking Glass Host captures frames from the guest OS using a capture API, and sends them to the Client—be it on the host OS (hypervisor) or another Virtual Machine—through a low-latency transfer protocol over shared memory.

You can get the host program in two ways:

• Download a pre-built binary from https://looking-glass.io/downloads (recommended)

• Download the source code as described in Building, then build the host.

Windows

To begin, you must first run the Windows VM with the changes noted above in either the libvirt Configuration or QEMU Commands sections.

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 the 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:

https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/upstream-virtio/

Please note that you must obtain version 0.1.161 or later.

If you encounter warnings or errors about driver signatures, ensure secure boot is turned off in the bios/UEFI settings of your virtual machine.

Installing the Looking Glass Service

After installing your IVSHMEM driver, we can now install the Looking Glass Host onto our Windows Virtual Machine.

1. First, run looking-glass-host-setup.exe as an administrator (Why?)

2. You will be greeted by an intro screen. Press Next to continue.

3. You are presented with the GPLv2 license. Please read and agree to the license by pressing Agree.

4. You can change the install path if you wish, otherwise press Next to continue.

5. You may enable or disable options on this screen to configure the installation. The default values are recommended for most users. Press Install to begin installation.

6. After a few moments, installation will complete, and you will have a running instance of Looking Glass. If you experience failures, you can see them in the install log appearing in the middle of the window.

7. Press Close to exit the installer.

Command line users can run looking-glass-host-setup.exe /S to execute a silent install with default options selected. Further configuration from the command line can be done with flags. You can list all available flags by running looking-glass-host-setup.exe /?.