DXVK-NVAPI

Alternative NVAPI implementation on top of DXVK

This repository provides an alternative implementation of NVIDIA's NVAPI/NVOFAPI library for usage with DXVK and VKD3D-Proton. Its way of working is similar to DXVK-AGS, but adjusted and enhanced for NVAPI.

This implementation currently offers entry points for supporting the following features in applications:

• NVIDIA DLSS for Vulkan, by supporting the relevant adapter information by querying from Vulkan.
• NVIDIA DLSS for D3D11 and D3D12, by querying from Vulkan and forwarding the relevant calls into DXVK / VKD3D-Proton.
• NVIDIA Reflex, by forwarding the relevant calls into either DXVK / VKD3D-Proton, its custom Vulkan layer or LatencyFleX.
• Several NVAPI D3D11 extensions, among others SetDepthBoundsTest and UAVOverlap, by forwarding the relevant calls into DXVK.
• NVIDIA PhysX, by supporting entry points for querying PhysX capabilities.
• Several GPU topology related methods for adapter and display information, by querying from DXVK and Vulkan.

Note that DXVK-NVAPI does not implement DLSS, Reflex or PhysX. It mostly forwards the relevant calls.

While originally being developed for usage with Unreal Engine 4, most notably for Assetto Corsa Competizione, more entry points have been added over time for enabling other NVIDIA related technologies. DXVK-NVAPI does not and will never cover the complete surface of NVIDIA's NVAPI. It is not meant as a full replacement, but rather as an addition to DXVK and VKD3D-Proton to enable several GPU features.

Requirements

This implementation is supposed to be used on Linux using Wine or derivatives like Proton. Usage on Windows is discouraged. Please do not replace nvapi.dll/nvapi64.dll/nvofapi64.dll on Windows from NVIDIA's driver package with this version. DXVK-NVAPI uses several DXVK and VKD3D-Proton extension points, thus using DXVK (D3D11 and DXGI) is a requirement. Using Wine's D3D11 or DXGI implementation will fail. Usage of DXVK-NVAPI is not restricted to NVIDIA GPUs, though the default behavior is to skip GPUs not running the NVIDIA proprietary driver or Mesa NVK. Some entry points offer no functionality or make no sense when a different GPU vendor is detected. DLSS requires an NVIDIA GPU, Turing or newer, running the proprietary driver.

In order to support Vulkan flavor of NVIDIA Reflex, an additional Vulkan layer is required which intercepts (technically invalid) Vulkan calls made by DXVK-NVAPI, enriches them with extra data, and forwards to a Vulkan driver that supports VK_NV_low_latency2 device extension.

When available, DXVK-NVAPI uses NVIDIA's NVML management library to query temperature, utilization and others for NVIDIA GPUs. See wine-nvml how to add NVML support to Wine/Proton.

How to build

Like DXVK, this library is being built as a Windows DLL using MinGW. DXVK-NVAPI requires MinGW-w64 compiler and headers version 9 or newer, the Meson build system at least version 0.58 and Python 3 (needed for a prebuild validation script). This project uses git submodules. Ensure to fetch the submodules while or after cloning the repository, e.g. with git clone --recurse-submodules git@github.com:jp7677/dxvk-nvapi.git.

The Vulkan Reflex layer has higher requirements: Meson 1.0 and a C++ compiler that supports C++20 standard. It is recommended (and assumed) that the layer is built as Linux-side library, and as such this compiler should target Linux and not be a cross-compiler like MinGW.

Run:

./package-release.sh master /your/path [--disable-layer] [--enable-tests]

Alternatively DXVK-Docker provides a way for a build setup using docker/podman. Prebuilt binaries of release versions are available at https://github.com/jp7677/dxvk-nvapi/releases. GitHub Actions is set up for building development snapshots.

How to use

Support for DXVK-NVAPI has been added to popular game launchers. See their respective documentation for usage and updates of DXVK-NVAPI.

Steam Play / Proton

Proton 9.0 includes DXVK-NVAPI and enables it by default for all titles with a few exceptions. Proton 9.0 can force-enable DXVK-NVAPI for titles that have DXVK-NVAPI disabled by default and also for non-NVIDIA GPUs when setting PROTON_FORCE_NVAPI=1. Contrary, PROTON_DISABLE_NVAPI disables DXVK-NVAPI.

• Copy and replace nvapi.dll/nvapi64.dll/nvofapi64.dll into the dist/lib/wine/nvapi/dist/lib64/wine/nvapi folder of your Proton installation, e.g. in ~/.steam/steam/steamapps/common/Proton 9.0/ for manually updating the included version.

Proton Experimental Bleeding Edge additionally always contains the latest DXVK-NVAPI development (master) version.

Proton 8.0 includes DXVK-NVAPI and enables it by default for a lot of titles. Use PROTON_ENABLE_NVAPI=1 for that version as game launch argument in Steam to enable DXVK-NVAPI for other titles.

Wine / Wine-Staging

Wine does not includes DXVK-NVAPI.

• Copy nvapi.dll/nvapi64.dll/nvofapi64.dll into the syswow64/system32 folder of your x86/x64 Wine prefix.
• Ensure that Wine uses the native version of nvapi/nvapi64, e.g. with WINEDLLOVERRIDES=nvapi,nvapi64=n. This applies only to Wine versions that ship their own NVAPI implementation, e.g. Wine-Staging older than 7.22. Generally this is no longer needed nowadays.
• Ensure that DXVK is installed in your x86/x64 Wine prefix.
• Ensure that Wine uses DXVK's dxgi.dll, e.g. with WINEDLLOVERRIDES=dxgi=n.
• Set DXVK_ENABLE_NVAPI=1 to disable DXVK's nvapiHack in DXVK.

DXVK 1.10 and older does not support DXVK_ENABLE_NVAPI. Disable the nvapiHack in DXVK 1.10 and older with dxgi.nvapiHack = False set in a DXVK configuration file, see dxvk.conf.

Non-NVIDIA GPU

Using DXVK-NVAPI with other GPU vendors / drivers has very limited use. Outside of testing, only Reflex (LatencyFlex) or HDR entry points provide benefits. This requires DXVK to see the GPU as an NVIDIA GPU. Use DXVK_CONFIG="dxgi.hideAmdGpu = True" to spoof an AMD GPU as NVIDIA GPU. Use DXVK_CONFIG="dxgi.customVendorId = 10de" for generally spoofing an NVIDIA GPU.

Setting DXVK_NVAPI_ALLOW_OTHER_DRIVERS=1 is needed for successful DXVK-NVAPI initialization when using a driver other than the NVIDIA proprietary driver or Mesa NVK. The reported driver version on drivers other than the NVIDIA proprietary driver will be 999.99. Overriding the reported driver version is still recommended. The reported GPU arrchitecture for other vendors is always Pascal to prevent attempts to initialize DLSS. This behavior cannot be changed without modifying the source code.

Vulkan Reflex layer

The Vulkan Reflex layer, when built as a Linux-side layer, is not installed into a Wine prefix. Instead it's installed like any other Vulkan implicit layer. It is distributed as a pair of files:

• VkLayer_DXVK_NVAPI_reflex.json (the layer manifest)
• libdxvk_nvapi_vkreflex_layer.so (the layer library)

To make it discoverable by your Vulkan loader:

1. Do one of the following:
   • Export full path to the directory containing the layer manifest in VK_ADD_IMPLICIT_LAYER_PATH environment variable (e.g. VK_ADD_IMPLICIT_LAYER_PATH="${HOME}/dxvk-nvapi/layer")
     • Note that VK_ADD_IMPLICIT_LAYER_PATH works only with Vulkan loader v1.3.296 or newer
     • If you already have VK_ADD_IMPLICIT_LAYER_PATH set and pointing to a directory with some other implicit layer manifest, it is possible to pass multiple paths by separating them with :
   • Install the layer manifest into one of default implicit layer search paths (e.g. ${XDG_DATA_HOME}/vulkan/implicit_layer.d where Steam usually installs its layers)
2. If needed, edit the layer manifest to ensure that its library_path points to the layer library
   • For example, if the layer library is in the same directory as the layer manifest, the path should be ./libdxvk_nvapi_vkreflex_layer.so
     • Note that the distributed layer manifest by default assumes this scenario; therefore there is no need to edit the manifest if the layer library is kept in the same directory as the manifest file
   • For other scenarios where the layer library is nearby, relative paths work as well (e.g. ../../../lib/libdxvk_nvapi_vkreflex_layer.so)
   • It's also possible to provide full path to the layer library (e.g. /home/user/dxvk-nvapi/layer/libdxvk_nvapi_vkreflex_layer.so)
   • Finally, if the layer library is in one of the paths searched by dynamic linker (like /usr/lib, this depends on the distro), it's possible to set the library path to just the name of the layer library: "library_path": "libdxvk_nvapi_vkreflex_layer.so"

Because the layer could interfere with other Vulkan applications that don't use Reflex, it is currently disabled by default even when installed. To enable it, export DXVK_NVAPI_VKREFLEX=1 as environment variable. When an application attempts to use Vulkan Reflex and the layer isn't installed and enabled, the following message should be logged at info log level: info:nvapi64:<-NvAPI_Vulkan_InitLowLatencyDevice: Not supported, with an explanation directing the user to verify the layer's setup.

Running env DXVK_NVAPI_VKREFLEX=1 vulkaninfo can serve as a quick setup check to verify that both files are in correct locations. If the layer manifest was found, there will be an entry like VK_LAYER_DXVK_NVAPI_reflex (DXVK-NVAPI Vulkan Reflex compatibility layer) on the list of discovered Vulkan layers. Additionally, if the layer manifest was found but the layer library couldn't be loaded (perhaps due to incorrect library_path in the manifest), an error similar to ERROR: [Loader Message] Code 0 : /home/user/.local/share/vulkan/implicit_layer.d/./libdxvk_nvapi_vkreflex_layer.so: cannot open shared object file: No such file or directory will be logged on stderr before any standard output.

Like any other (glibc-based) Linux shared library, layer compiled on a system with newer version of glibc will not run on systems with older version of glibc. If you are running a distro with older glibc than the ones prebuilt binaries are distributed for, it is likely that building your own library from source will be required.

Tweaks, debugging and troubleshooting

See the DXVK-NVAPI Wiki for common issues and workarounds.

The following environment variables tweak DXVK-NVAPI's runtime behavior:

• DXVK_NVAPI_DRIVER_VERSION lets you override the reported driver version. Valid values are numbers between 100 and 99999. Use e.g. DXVK_NVAPI_DRIVER_VERSION=47141 to report driver version 471.41.
• DXVK_NVAPI_ALLOW_OTHER_DRIVERS, when set to 1, allows DXVK-NVAPI to initialize for a non-NVIDIA GPU.
• DXVK_NVAPI_DISABLE_ENTRYPOINTS, when set to a comma-separated list of NVAPI entrypoint names, will hide their implementation from the application. For example, DXVK_NVAPI_DISABLE_ENTRYPOINTS=NvAPI_D3D11_BeginUAVOverlap,NvAPI_D3D11_EndUAVOverlap will report D3D11 barrier control extensions as not available.
• DXVK_NVAPI_GPU_ARCH, when set to one of supported NVIDIA GPU architecture IDs will override reported GPU architecture. Currently supported values are:
  • GK100 (Kepler)
  • GM000 (Maxwell Gen1)
  • GM200 (Maxwell Gen2)
  • GP100 (Pascal)
  • GV100 (Volta)
  • TU100 (Turing)
  • GA100 (Ampere)
  • AD100 (Ada)
  • GB200 (Blackwell)
• DXVK_NVAPI_LOG_LEVEL set to info prints log statements. The default behavior omits any logging. Please fill an issue if using log servery info creates log spam. Setting severity to trace logs all entry points enter and exits, this has a severe effect on performance. All other log levels will be interpreted as none.
• DXVK_NVAPI_LOG_PATH enables file logging additionally to console output and sets the path where the log file nvapi.log/nvapi64.log/nvofapi64.log should be written to. Log statements are appended to an existing file. Please remove this file once in a while to prevent excessive grow. This requires DXVK_NVAPI_LOG_LEVEL set to info or trace.

The following environment variables tweak DXVK-NVAPI's Vulkan Reflex layer's runtime behavior:

• DXVK_NVAPI_VKREFLEX=1 enables the layer; the layer is disabled by default when this isn't set
• DISABLE_DXVK_NVAPI_VKREFLEX disables the layer (overriding DXVK_NVAPI_VKREFLEX=1) when set to any nonempty value
• DXVK_NVAPI_VKREFLEX_LAYER_LOG_LEVEL configures logging verbosity, supported values are none (default), error, warn, info, trace, debug and integer values from 0 to 5 inclusive that correspond to named log levels
• DXVK_NVAPI_VKREFLEX_EXPOSE_EXTENSION=1 causes the layer to report support for VK_NV_low_latency device extension, this is usually unnecessary as modern NVIDIA drivers already claim support for it and exposing it from the layer can cause issues in some games (notably Indiana Jones and the Great Circle)
• DXVK_NVAPI_VKREFLEX_INJECT_SUBMIT_FRAME_IDS=1 and DXVK_NVAPI_VKREFLEX_INJECT_PRESENT_FRAME_IDS=1 cause the layer to inject frame IDs into vkQueueSubmit* and vkQueuePresentKHR Vulkan commands respectively based on the latency markers set by the application with NvAPI_Vulkan_SetLatencyMarker, possibly helping the driver correlate the calls but could interfere with application's own present IDs; enabling either enables VK_KHR_present_id device extension and related presentID feature
  • DXVK_NVAPI_VKREFLEX_ALLOW_FALLBACK_TO_OOB_FRAME_ID=0 disables fallback to out-of-band frame IDs in submit and present calls
  • DXVK_NVAPI_VKREFLEX_ALLOW_FALLBACK_TO_PRESENT_FRAME_ID=0 disables fallback to present frame IDs in submit calls
  • DXVK_NVAPI_VKREFLEX_ALLOW_FALLBACK_TO_SIMULATION_FRAME_ID=0 disables fallback to simulation frame IDs in submit calls

Additionally, GitHub Actions provide build artifacts from different toolchains. In very rare situations a non-gcc build might provide better results.

Using those tweaks is exclusively meant for troubleshooting. Regular usage is discouraged and may result in unwanted side effects. Please open an issue if using one of the tweaks is mandatory for a specific title/scenario.

This project provides a test suite. Run the package script with --enable-tests (see above) to build nvapi64-tests.exe. Running the tests executable without arguments queries the local system and provides system information about visible GPUs:

DXVK_LOG_LEVEL=none WINEDEBUG=-all WINEDLLOVERRIDES=dxgi,nvapi64=n wine nvapi64-tests.exe

The test executable also runs on Windows against NVIDIA's nvapi64.dll. Ensure that DXVK-NVAPI's nvapi64.dllis not present in the current PATH for this scenario.

The actual unit tests can be run with nvapi64-tests.exe [@unit-tests] to validate DXVK-NVAPI's internal implementation.

Producing a debug build and starting a debugging session with the test suite can be achieved with the following snippet:

meson setup --reconfigure --cross-file "./build-win64.txt" --buildtype "debugoptimized" -Denable_tests=True build
meson compile -C build

DXVK_LOG_LEVEL=none DXVK_NVAPI_LOG_LEVEL=none WINEDEBUG=-all WINEDLLOVERRIDES=nvapi64=n WINEPATH=build/src winedbg --gdb build/tests/nvapi64-tests.exe [@all]

Once the debug session has started, use c to start/continue execution and a.o. bt to show a proper stacktrace after a segmentation fault. Ensure to have no other native nvapi64.dll in the Wine prefix, otherwise this one gets precedence over the one found in WINEPATH.

References and inspirations

• DXVK
• DXVK-AGS
• VKD3D-Proton
• NVAPI
• NVAPI Open Source SDK
• NVAPI GitHub Project
• NVAPI (wine-staging) standalone

Many thanks to the corresponding authors!