d50e8554b9
This adds some documentation for the current feature-set in Zink, explaining what extensions are currently needed for what functionality. Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7116>
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3.3 KiB
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103 lines
3.3 KiB
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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 features of the Vulkan driver.
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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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* ``wideLines``
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* ``largePoints``
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* ``alphaToOne``
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* ``shaderClipDistance``
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* ``VkPhysicalDeviceLimits``:
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* ``maxClipDistances`` ≥ 6
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* Instance extensions:
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* `VK_KHR_get_physical_device_properties2`_
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* `VK_KHR_external_memory_capabilities`_
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* Device extensions:
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* `VK_KHR_maintenance1`_
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* `VK_KHR_external_memory`_
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OpenGL 3.0
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^^^^^^^^^^
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For OpenGL 3.0 support, the following additional device extensions are
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required to be exposed and fully supported:
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* `VK_EXT_transform_feedback`_
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* `VK_EXT_conditional_rendering`_
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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 <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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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 FreeNode
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<irc://irc.freenode.net/zink>`_ and say hi!
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.. _VK_KHR_get_physical_device_properties2: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_get_physical_device_properties2.html
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.. _VK_KHR_external_memory_capabilities: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_external_memory_capabilities.html
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.. _VK_KHR_maintenance1: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_maintenance1.html
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.. _VK_KHR_external_memory: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_KHR_external_memory.html
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.. _VK_EXT_transform_feedback: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_transform_feedback.html
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.. _VK_EXT_conditional_rendering: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VK_EXT_conditional_rendering.html
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