Triton: DirectX 11 driver for QEMU

DirectX 11 driver Triton has been developed by combining Neptune and the QEMU virtual machines. Neptune is a Direct3D protocol forwarding layer for VirtIO, which allows for serialization of Direct3D API calls across the hypervisor boundary. This has enabled running Wine games on a Linux guest with a Linux host faster than with DXVK. Triton, along with Neptune, brings full DirectX 11 support to QEMU virtual machines.

The Neptune Mesa drivers construct d3d11.dll and dxgi.dll, fully implementing the Direct3D API set. However, this approach has limitations, such as poor performance due to CPU blitting by the window compositor and the inability to replace system files without causing issues for games with anti-cheats. Therefore, implementing the DirectX DDIs (Device Driver Interface) is a more user-friendly solution.

To implement the DirectX DDIs, QEMU has to create the UMD (User-Mode Driver) and KMD (Kernel-Mode Driver) interface. The KMD communicates with the VirtIO device, which is implemented by the graphics vendor to drive the actual hardware. For Wine, Triton was implemented to intercept API calls. QEMU has used anonymix007's branch as the base for the KMD, as it has more features working on the KMD side compared to other open-source implementations.

Two open-source implementations have been used for references in creating Triton. Mesa offers a DirectX 10 UMD, which performs state tracking for OpenGL and emits Gallium API calls, and then converts them into native graphics driver APIs using the Gallium backend driver. VirtualBox has the only working open-source DirectX 11 UMD, which translates DDI calls into an intermediate bytecode and then interprets the bytecode into DirectX API calls. However, this driver is not easily adoptable for QEMU due to compatibility issues.