[doc] add requirements page

doc/index.rst

@@ -10,6 +10,7 @@ systems for legacy programs that require high-performance graphics.
 .. toctree::
    :maxdepth: 2
 
+   requirements
    usage
    install
    build

doc/requirements.rst

@@ -0,0 +1,82 @@
+.. _requrements:
+
+Requirements
+############
+
+.. _minimum_:
+
+Minimum
+-------
+
+The most basic requirement to make use of Looking Glass is to have a system
+with two GPUs, the following configurations are valid:
+
+* Two descrete GPUs (dGPU)
+* A descrete GPU and an integrated (iGPU) such as is common in laptops.
+* A descrete GPU or iGPU and a virtual GPU (vGPU) as supported by some
+  hardware.
+
+.. note::
+  Please be aware that iGPU users may be limited in the resolution and refresh
+  rate possible with Looking Glass due to the memory bandwidth limitations
+  imposed due to the iGPU sharing system RAM for GPU usage.
+
+Looking Glass aims to achieve the lowest possible latency and as such it
+is important that you do not overload your system. The minimum recommended CPU
+to obtain a decent expereience with Looking Glass is 6 cores or more, with
+Hyper-threading (>= 12 threads).
+
+PCIe bandwidth can also be a limiting factor, as such both GPUs should have a
+minimum of 8 lanes (x8) at PCIe3 speeds, or 4 lanes (x4) at PCIe4 speeds.
+
+The GPU used for the guest virtual machine must have either a physical monitor
+attached to it, or a cheap dummy plug. The guest operating system (most notibly
+Windows) will disable the GPU output if there is nothing attached to it and
+Looking Glass will not be able to function. If you are using a vGPU the virtual
+device should already have a virtual monitor attached to it negating this
+requirement.
+
+.. _recommended_:
+
+Recommended
+-----------
+
+At this time the recommended configuration is as follows:
+
+* CPU 8 cores (16 threads) or better @ 3.0GHz or faster (full cores, not
+  efficiency cores).
+
+* Two descrete GPUs consisting of:
+
+  * AMD or Intel brand GPU for the client application (usually your host system).
+  * NVIDIA brand GPU for the guest system (virtual machine).
+
+The reason for these reccomendations are as follows:
+
+AMD or Intel for the client
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+AMD and Intel both support the `DMABUF` feature which enables offloading memory
+transfers to the GPU hardware. Please note that making use of this feature
+requires :doc:`loading the KVMFR kernel module <module>`.
+
+Additionally AMD GPUs suffer stabillity issues when operating as a passthrough
+device and as such we do not recommend their usage for such purposes. Models of
+note that have issues include but are not limited to the entire Polaris, Vega,
+Navi and BigNavi GPU series. Vega and Navi are notibly the worst and should be
+avoided for virtualization usage.
+
+NVIDIA for the guest
+^^^^^^^^^^^^^^^^^^^^
+
+NVIDIA unlike AMD do not seem to suffer from the same stabillity issues as AMD
+GPUs when operating as a passthrough GPU, however due to the closed source
+nature of their drivers NVIDIA can not make use of the DMABUF feature in the
+Linux kernel and as such it is not recommended for use as the host GPU.
+
+`It has been said <https://github.com/NVIDIA/open-gpu-kernel-modules/discussions/243#discussioncomment-3283415>`_
+that the open-source NVIDIA drivers as of release 525 will enable this support
+and we have made changes to `an experiemental branch <https://github.com/gnif/LookingGlass/tree/dmabuf-test>`_
+to support this, however until NVIDIA release this version and we can test these
+changes against the driver, support will not be included in the release builds
+of Looking Glass.