4eef5628c8
The custom envvar directive is strange. It overloads the global namespace, where there's already a well-known envvar directive, but the envvar role won't resolve to envvars defined using the custom directive. It's not really critical to declare the type and default value here, and many descriptions already include this. Let's just use the plain one, and let the description take care of the details where needed. Reviewed-by: Yonggang Luo <luoyonggang@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19593>
300 lines
7.4 KiB
ReStructuredText
300 lines
7.4 KiB
ReStructuredText
Zink
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====
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Overview
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--------
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The Zink driver is a Gallium driver that emits Vulkan API calls instead
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of targeting a specific GPU architecture. This can be used to get full
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desktop OpenGL support on devices that only support Vulkan.
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Features
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--------
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The feature-level of Zink depends on two things; what's implemented in Zink,
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as well as the capabilities of the Vulkan driver.
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The feature-levels implemented by Zink are exposed by `Vulkan Profiles
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<https://dev.vulkan.org/tools#vulkan-profiles>`__ in the
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:file:`VP_ZINK_requirements.json` profiles file.
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Used with the `Vulkan Profiles tools <https://github.com/KhronosGroup/Vulkan-Profiles>`__,
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we can compare the ZINK profiles with Vulkan devices profiles generated with
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`Vulkaninfo <https://vulkan.lunarg.com/doc/view/latest/windows/vulkaninfo.html>`__
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or `downloaded from GPUinfo.org`_
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to establish the feature-levels supported by these drivers.
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OpenGL 2.1
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^^^^^^^^^^
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OpenGL 2.1 is the minimum version Zink can support, and will always be
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exposed, given Vulkan support. There's a few features that are required
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for correct behavior, but not all of these are validated; instead you'll
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see rendering-issues and likely validation error, or even crashes.
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Here's a list of those requirements:
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* Vulkan 1.0
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* ``VkPhysicalDeviceFeatures``:
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* ``logicOp``
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* ``fillModeNonSolid``
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* ``alphaToOne``
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* ``shaderClipDistance``
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* Device extensions:
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* :ext:`VK_KHR_maintenance1`
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* :ext:`VK_KHR_create_renderpass2`
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* :ext:`VK_KHR_imageless_framebuffer`
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* :ext:`VK_KHR_timeline_semaphore`
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* :ext:`VK_EXT_custom_border_color` with ``customBorderColorWithoutFormat``
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* :ext:`VK_EXT_provoking_vertex`
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* :ext:`VK_EXT_line_rasterization`, with the following ``VkPhysicalDeviceLineRasterizationFeaturesEXT``:
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* ``rectangularLines``
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* ``bresenhamLines``
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* ``smoothLines``
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* ``stippledRectangularLines``
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* ``stippledBresenhamLines``
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* ``stippledSmoothLines``
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* :ext:`VK_KHR_swapchain_mutable_format`
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* :ext:`VK_EXT_border_color_swizzle`
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* :ext:`VK_KHR_descriptor_update_template`
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In addition to this, :ext:`VK_KHR_external_memory` is required to support the
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DRI code-path.
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We also require either the :ext:`VK_EXT_scalar_block_layout` extension or
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Vulkan 1.2, with the ``scalarBlockLayout`` feature.
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OpenGL 3.0
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^^^^^^^^^^
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For OpenGL 3.0 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``independentBlend``
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* Device extensions:
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* :ext:`VK_EXT_transform_feedback`
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* :ext:`VK_EXT_conditional_rendering`
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OpenGL 3.1
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^^^^^^^^^^
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For OpenGL 3.1 support, the following additional ``VkPhysicalDeviceLimits``
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are required:
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* ``maxPerStageDescriptorSamplers`` ≥ 16
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OpenGL 3.2
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^^^^^^^^^^
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For OpenGL 3.2 support, the following additional requirements must be
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supported, although some of these might not actually get verified:
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* ``VkPhysicalDeviceFeatures``:
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* ``depthClamp``
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* ``geometryShader``
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* ``shaderTessellationAndGeometryPointSize``
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* Device extensions:
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* :ext:`VK_EXT_depth_clip_enable`
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OpenGL 3.3
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^^^^^^^^^^
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For OpenGL 3.3 support, the following additional requirements must be
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supported, although some of these might not actually get verified:
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* ``VkPhysicalDeviceFeatures``:
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* ``occlusionQueryPrecise``
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* Device extensions:
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* :ext:`VK_EXT_vertex_attribute_divisor`
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OpenGL 4.0
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^^^^^^^^^^
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For OpenGL 4.0 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``sampleRateShading``
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* ``tessellationShader``
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* ``imageCubeArray``
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* Device extensions:
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* :ext:`VK_KHR_maintenance2`
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* Formats requiring ``VK_FORMAT_FEATURE_UNIFORM_TEXEL_BUFFER_BIT``:
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* ``VK_FORMAT_R32G32B32_SFLOAT``
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* ``VK_FORMAT_R32G32B32_SINT``
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* ``VK_FORMAT_R32G32B32_UINT``
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OpenGL 4.1
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^^^^^^^^^^
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For OpenGL 4.1 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``multiViewport``
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* ``VkPhysicalDeviceLimits``
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* ``maxImageDimension2D`` ≥ 16384
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* ``maxViewports`` ≥ 16
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OpenGL 4.2
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^^^^^^^^^^
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For OpenGL 4.2 support, the following additional requirements must be
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supported:
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* Device extensions:
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* :ext:`VK_EXT_image_2d_view_of_3d`
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* ``VkPhysicalDeviceLimits``:
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* ``shaderStorageImageExtendedFormats``
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* ``shaderStorageImageWriteWithoutFormat``
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* For Vulkan 1.2 and above:
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* ``VkPhysicalDeviceVulkan11Features``:
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* ``shaderDrawParameters``
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* ``vertexPipelineStoresAndAtomics``
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* ``fragmentStoresAndAtomics``
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* ``textureCompressionBC``
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* For Vulkan 1.1 and below:
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* Device extensions:
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* :ext:`VK_KHR_shader_draw_parameters`
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OpenGL 4.3
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^^^^^^^^^^
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For OpenGL 4.3 support, the following additional requirements must be
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supported:
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* ``VkPhysicalDeviceFeatures``:
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* ``robustBufferAccess``
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* Formats requiring ``VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT``:
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* ``VK_FORMAT_R8G8B8A8_UNORM``
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* ``VK_FORMAT_R8G8B8A8_SRGB``
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* ``VK_FORMAT_R16_UNORM``
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* ``VK_FORMAT_R16G16_UNORM``
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* ``VK_FORMAT_R16_SNORM``
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* ``VK_FORMAT_R16G16_SNORM``
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* ``VK_FORMAT_D32_SFLOAT_S8_UINT``
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OpenGL 4.4
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^^^^^^^^^^
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For OpenGL 4.4 support, the following additional requirements must be
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supported:
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* Formats requiring ``VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT``:
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* ``VK_FORMAT_B10G11R11_UFLOAT_PACK32``
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* Device extensions:
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* :ext:`VK_KHR_sampler_mirror_clamp_to_edge`
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OpenGL 4.5
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^^^^^^^^^^
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For OpenGL 4.5 support, the following additional ``VkPhysicalDeviceFeatures``
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are required to be supported
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* ``shaderCullDistance``
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OpenGL 4.6
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^^^^^^^^^^
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For OpenGL 4.6 support, the following additional ``VkPhysicalDeviceFeatures``
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are required to be supported
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* ``VkPhysicalDeviceFeatures``:
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* ``samplerAnisotropy``
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* ``pipelineStatisticsQuery``
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* ``depthBiasClamp``
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* Device extensions:
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* :ext:`VK_KHR_draw_indirect_count`
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Debugging
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---------
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There's a few tools that are useful for debugging Zink, like this environment
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variable:
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.. envvar:: ZINK_DEBUG
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Accepts the following comma-separated list of flags:
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``nir``
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Print the NIR form of all shaders to stderr.
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``spirv``
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Write the binary SPIR-V form of all compiled shaders to a file in the
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current directory, and print a message with the filename to stderr.
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``tgsi``
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Print the TGSI form of TGSI shaders to stderr.
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``validation``
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Dump Validation layer output.
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``sync``
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Emit full synchronization barriers before every draw and dispatch.
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``compact``
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Use a maximum of 4 descriptor sets
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``noreorder``
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Do not reorder or optimize GL command streams
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``gpl``
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Force using Graphics Pipeline Library for all shaders
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Vulkan Validation Layers
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^^^^^^^^^^^^^^^^^^^^^^^^
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Another useful tool for debugging is the `Vulkan Validation Layers
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<https://github.com/KhronosGroup/Vulkan-ValidationLayers/blob/master/README.md>`__.
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The validation layers effectively insert extra checking between Zink and the
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Vulkan driver, pointing out incorrect usage of the Vulkan API. The layers can
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be enabled by setting the environment variable :envvar:`VK_INSTANCE_LAYERS` to
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"VK_LAYER_KHRONOS_validation". You can read more about the Validation Layers
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in the link above.
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IRC
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---
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In order to make things a bit easier to follow, we have decided to create our
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own IRC channel. If you're interested in contributing, or have any technical
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questions, don't hesitate to visit `#zink on OFTC
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<irc://irc.oftc.net/zink>`__ and say hi!
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.. _downloaded from GPUinfo.org: https://www.saschawillems.de/blog/2022/03/12/vulkan-profiles-support-for-the-vulkan-hardware-capability-viewer-and-database/
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