# vulkan-wsi-layer **Repository Path**: mirrors_community_gitlab_freedesktop/vulkan-wsi-layer ## Basic Information - **Project Name**: vulkan-wsi-layer - **Description**: No description available - **Primary Language**: Unknown - **License**: MIT - **Default Branch**: main - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2022-03-16 - **Last Updated**: 2025-11-23 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README # Vulkan® Window System Integration Layer ## Introduction This project is a Vulkan® layer which implements some of the Vulkan® window system integration extensions such as `VK_KHR_swapchain`. The layer is designed to be GPU vendor agnostic when used as part of the Vulkan® ICD/loader architecture. Our vision for the project is to become the de facto implementation for Vulkan® window system integration extensions so that they need not be implemented in the ICD; instead, the implementation of these extensions are shared across vendors for mutual benefit. The project currently implements support for `VK_EXT_headless_surface` and its dependencies. Experimental support for `VK_KHR_wayland_surface` can be enabled via a build option [as explained below](#building-with-wayland-support). ### Implemented Vulkan® extensions The Vulkan® WSI Layer in addition to the window system integration extensions implements the following extensions: * Instance extensions * VK_KHR_get_surface_capabilities2 * VK_EXT_surface_maintenance1 * VK_KHR_surface_maintenance1 * Device extensions * VK_KHR_shared_presentable_image * VK_EXT_image_compression_control_swapchain * VK_KHR_present_id * VK_KHR_present_id2 * VK_KHR_present_wait * VK_KHR_present_wait2 * VK_EXT_swapchain_maintenance1 * VK_KHR_swapchain_maintenance1 * VK_EXT_present_mode_fifo_latest_ready (For Headless and Wayland only) * VK_KHR_present_mode_fifo_latest_ready (For Headless and Wayland only) * VK_KHR_swapchain_mutable_format (For Headless and Wayland only) ## Building ### Dependencies * [CMake](https://cmake.org) version 3.4.3 or above. * C++17 compiler. * Vulkan® loader and associated headers with support for the `VK_EXT_headless_surface` extension and for the Vulkan 1.1, or later API. The Vulkan WSI Layer uses Vulkan extensions to communicate with the Vulkan ICDs. The ICDs installed in the system are required to support the following extensions: * Instance extensions: * VK_KHR_get_physical_device_properties_2 * VK_KHR_external_fence_capabilities * VK_KHR_external_semaphore_capabilities * VK_KHR_external_memory_capabilities * Device extensions (only required when Wayland support is enabled): * VK_EXT_image_drm_format_modifier * VK_KHR_image_format_list * VK_EXT_external_memory_dma_buf * VK_KHR_external_memory_fd * VK_KHR_external_fence_fd * Any dependencies of the above extensions ### Vulkan Header Version The Vulkan WSI Layer has been validated against Vulkan header version 1.4.325. If you are using a Vulkan header version newer than this, a warning will appear during compilation. ### Building the Vulkan® loader This step is not necessary if your system already has a loader and associated headers with support for the `VK_EXT_headless_surface` extension. We include these instructions for completeness. ``` git clone https://github.com/KhronosGroup/Vulkan-Loader.git mkdir Vulkan-Loader/build cd Vulkan-Loader/build ../scripts/update_deps.py cmake -C helper.cmake .. make make install ``` ### Building with headless support The layer requires a version of the loader and headers that includes support for the `VK_EXT_headless_surface` extension. By default, the build system will use the system Vulkan® headers as reported by `pkg-config`. This may be overriden by specifying `VULKAN_CXX_INCLUDE` in the CMake configuration, for example: ``` cmake . -DVULKAN_CXX_INCLUDE="path/to/vulkan-headers" ``` If the loader and associated headers already meet the requirements of the layer then the build steps are straightforward: ``` cmake . -Bbuild make -C build ``` ### Building with Wayland support In order to build with Wayland support the `BUILD_WSI_WAYLAND` build option must be used, the `SELECT_EXTERNAL_ALLOCATOR` option has to be set to a graphics memory allocator (currently only dma_buf_heaps is supported) and the `KERNEL_HEADER_DIR` option must be defined as the directory that includes the kernel headers. source. ``` cmake . -DVULKAN_CXX_INCLUDE="path/to/vulkan-header" \ -DBUILD_WSI_HEADLESS=0 \ -DBUILD_WSI_WAYLAND=1 \ -DSELECT_EXTERNAL_ALLOCATOR=dma_buf_heaps \ -DKERNEL_HEADER_DIR="path/to/linux-kernel-headers" ``` In the command line above, `-DBUILD_WSI_HEADLESS=0` is used to disable support for `VK_EXT_headless_surface`, which is otherwise enabled by default. Note that a custom graphics memory allocator implementation can be provided using the `EXTERNAL_WSIALLOC_LIBRARY` option. For example, ``` cmake . -DVULKAN_CXX_INCLUDE="path/to/vulkan-header" \ -DBUILD_WSI_WAYLAND=1 \ -DEXTERNAL_WSIALLOC_LIBRARY="path/to/custom/libwsialloc" \ -DKERNEL_HEADER_DIR="path/to/linux-kernel-headers" ``` The `EXTERNAL_WSIALLOC_LIBRARY` option allows to specify the path to a library containing the implementation of the graphics memory allocator API, as described in [the wsialloc.h header file](util/wsialloc/wsialloc.h). The allocator is not only responsible for allocating graphics buffers, but is also responsible for selecting a suitable format that can be efficiently shared between the different devices in the system, e.g. GPU, display. It is therefore an important point of integration. It is expected that each system will need a tailored implementation, although the layer provides a generic dma_buf_heaps implementation that may work in systems that support linear formats. This is selected by the `-DSELECT_EXTERNAL_ALLOCATOR=dma_buf_heaps` option, as shown above. ### Wayland support with FIFO presentation mode The WSI Layer has 2 FIFO implementations for the Wayland backend. One that blocks in vkQueuePresent and one that uses a presentation thread. This is due to the fact that the FIFO implementation that utilises the presentation thread in the Wayland backend is not strictly conformant to the Vulkan specification, however it has a much better performance due to not needing to block in vkQueuePresent. By default, the WSI Layer uses the queue present blocking FIFO implementation when using Wayland swapchains. This can be switched to instead use the presentation thread implementation by including the build option `ENABLE_WAYLAND_FIFO_PRESENTATION_THREAD`, along with the other build options mentioned in "Building with Wayland support" section. ### Building with frame instrumentation support The layer can be built to pass frame boundary information down to other layers or ICD by making use of the [VK_EXT_frame_boundary extension](https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_frame_boundary.html). By enabling this feature, if application is not making use of the VK_EXT_frame_boundary extension, the layer will generate and pass down frame boundary events which enables the ability to instrument present submissions for applications that do not make use of this extension. In order to enable this feature `-DENABLE_INSTRUMENTATION=1` option can be passed at build time. ### Debug builds The layer can be built with different values of the CMAKE_BUILD_TYPE variable. When CMAKE_BUILD_TYPE is set to Debug, additional debugging functionality is enabled. For example, internal values stored inside the layer's different objects can be retrieved. These functions can be linked at runtime using dynamic loading mechanisms, such as dlsym(), with the provided layer shared library. The debug interface provides functions including: * vk_wsi_layer_debug_get_sc_image_drm_mod ## Installation Copy the shared library `libVkLayer_window_system_integration.so` and JSON configuration `VkLayer_window_system_integration.json` into a Vulkan® [implicit layer directory](https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderLayerInterface.md#linux-layer-discovery). ## Contributing We are open for contributions. * The software is provided under the MIT license. Contributions to this project are accepted under the same license. * Please also ensure that each commit in the series has at least one `Signed-off-by:` line, using your real name and email address. The names in the `Signed-off-by:` and `Author:` lines must match. If anyone else contributes to the commit, they must also add their own `Signed-off-by:` line. By adding this line the contributor certifies the contribution is made under the terms of the [Developer Certificate of Origin (DCO)](DCO.txt). * Questions, bug reports, et cetera are raised and discussed on the issues page. * Please make merge requests into the main branch. * Code should be formatted with clang-format using the project's .clang-format configuration. We use [pre-commit](https://pre-commit.com/) for local git hooks to help ensure code quality and standardization. To install the hooks run the following commands in the root of the repository: $ pip install pre-commit $ pre-commit install Contributors are expected to abide by the [freedesktop.org code of conduct](https://www.freedesktop.org/wiki/CodeOfConduct/). ### Implement a new WSI backend Instructions on how to implement a WSI backend can be found in the [README](wsi/README.md) in the wsi folder. ## Trace When using other layers to trace content with the WSI Layer, special attention should be paid to the order of the layers by the Vulkan® loader. The Vulkan WSI Layer should be placed after the trace layer as it implements entrypoints that may not be implemented by the ICD. One way to avoid these kinds of issues is by using an implicit [meta-layer](https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderLayerInterface.md#meta-layers) which will define the order of the layers and the WSI Layer should be placed at the bottom of the list. ## Khronos® Conformance This software is based on a published Khronos® Specification and is expected to pass the relevant parts of the Khronos® Conformance Testing Process when used as part of a conformant Vulkan® implementation.