.. _requirements:

Requirements and compatibility
##############################

.. _minimum:

Required
--------

Linux host
   A Linux system capable of running KVM/QEMU and building the Looking Glass
   Client. The client requires an EGL-capable graphics driver. X11 and Wayland
   are supported. For a responsive passthrough setup, at least six CPU cores
   with twelve hardware threads are required.

Windows guest
   A Windows 10 version 1903 or newer, or Windows 11, virtual machine. Looking
   Glass can create its own virtual monitor and does not require a physical
   monitor or dummy plug.

Shared memory
   An IVSHMEM device large enough for the maximum guest resolution and refresh
   rate. The KVMFR kernel module is recommended and is required for direct GPU
   imports.

Matching components
   The Looking Glass client, IDD, and OBS plugin (if used) must be of the same
   version. Legacy Host users must use the B7 stack described below.

The IDD can fall back to software processing if the Windows guest has no
suitable render GPU. This is useful for compatibility and basic applications,
such as word processing and spreadsheets, but hardware processing is strongly
recommended for lower latency and higher frame rates, especially games. Software
mode is SDR-only and does not provide the same performance as the GPU path.

.. seealso::

   :ref:`libvirt_determining_memory`

.. _recommended:

Recommended
-----------

For a responsive high-resolution setup, use:

* a host CPU with eight cores and sixteen threads or better, with full
  performance cores around 3 GHz or faster;
* the KVMFR kernel module rather than a plain shared-memory file;
* a host GPU and driver that support direct DMA imports; and
* a hardware render adapter in the Windows guest.

Reserve at least two physical CPU cores, or four threads, for Linux. Looking
Glass, QEMU, the Linux desktop and audio server all need host CPU time. High
refresh rates also raise shared-memory and GPU bandwidth requirements.

For a passed-through GPU, PCIe bandwidth can also limit performance. Use at
least eight PCIe 3.0 lanes or four PCIe 4.0 lanes where practical.

.. _connected_display:

Physical display and dummy plugs
--------------------------------

The IDD does not require a physical display or dummy plug: it creates a virtual
Windows monitor, including on systems without a passed-through display output.

A physical display, dummy plug or another virtual monitor is only required
when using the :doc:`Legacy Host Application </legacy_host>`, because that
application captures an existing Windows display.

.. _igpu_kvmfr_recommended:

Host GPU notes
--------------

AMD and Intel host GPUs commonly support the DMA-BUF path used by KVMFR. This
can reduce CPU work and avoid an extra system-memory copy. It is particularly
important for integrated GPUs, which already share memory bandwidth with the
CPU.

NVIDIA host GPUs require a driver configuration that supports DMA-BUF import.
If direct import is unavailable, the client falls back to a software copy.
Looking Glass still works, but uses more CPU and memory bandwidth.

Windows and HDR
---------------

Windows 10 (version 1903 or newer) remains supported. Current HDR and
wide-color-gamut display features depend on newer IddCx interfaces that the
driver checks at runtime, so they are normally available only on a compatible
Windows 11 installation. The IDD continues to use its SDR-compatible path when
those interfaces are unavailable.

Native HDR presentation on Linux requires the EGL renderer, Wayland
``color-management-v1`` support in the compositor, and an HDR-capable output.
When native HDR is unavailable, the client can map HDR content to SDR.