128 lines
4.8 KiB
Plaintext
128 lines
4.8 KiB
Plaintext
// Copyright (c) 2016-2018 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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include::meta/VK_KHR_external_memory_capabilities.txt[]
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*Last Modified Date*::
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2016-10-17
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*IP Status*::
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No known IP claims.
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*Interactions and External Dependencies*::
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- Interacts with `<<VK_KHR_dedicated_allocation>>`.
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- Interacts with `<<VK_NV_dedicated_allocation>>`.
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- Promoted to Vulkan 1.1 Core
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*Contributors*::
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- Ian Elliot, Google
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- Jesse Hall, Google
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- James Jones, NVIDIA
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An application may wish to reference device memory in multiple Vulkan
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logical devices or instances, in multiple processes, and/or in multiple
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APIs.
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This extension provides a set of capability queries and handle definitions
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that allow an application to determine what types of "`external`" memory
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handles an implementation supports for a given set of use cases.
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=== New Object Types
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None.
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=== New Enum Constants
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* ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_IMAGE_FORMAT_INFO_KHR
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* ename:VK_STRUCTURE_TYPE_EXTERNAL_IMAGE_FORMAT_PROPERTIES_KHR
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* ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_BUFFER_INFO_KHR
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* ename:VK_STRUCTURE_TYPE_EXTERNAL_BUFFER_PROPERTIES_KHR
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* ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ID_PROPERTIES_KHR
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* ename:VK_LUID_SIZE_KHR
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=== New Enums
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* elink:VkExternalMemoryHandleTypeFlagBitsKHR
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* elink:VkExternalMemoryFeatureFlagBitsKHR
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=== New Structs
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* slink:VkExternalMemoryPropertiesKHR
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* slink:VkPhysicalDeviceExternalImageFormatInfoKHR
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* slink:VkExternalImageFormatPropertiesKHR
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* slink:VkPhysicalDeviceExternalBufferInfoKHR
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* slink:VkExternalBufferPropertiesKHR
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* slink:VkPhysicalDeviceIDPropertiesKHR
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=== New Functions
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* flink:vkGetPhysicalDeviceExternalBufferPropertiesKHR
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=== Promotion to Vulkan 1.1
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All functionality in this extension is included in core Vulkan 1.1, with the
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KHR suffix omitted.
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The original type, enum and command names are still available as aliases of
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the core functionality.
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=== Issues
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1) Why do so many external memory capabilities need to be queried on a
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per-memory-handle-type basis?
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*PROPOSED RESOLUTION*: This is because some handle types are based on
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OS-native objects that have far more limited capabilities than the very
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generic Vulkan memory objects.
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Not all memory handle types can name memory objects that support 3D images,
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for example.
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Some handle types cannot even support the deferred image and memory binding
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behavior of Vulkan and require specifying the image when allocating or
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importing the memory object.
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2) Do the slink:VkExternalImageFormatPropertiesKHR and
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slink:VkExternalBufferPropertiesKHR structs need to include a list of memory
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type bits that support the given handle type?
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*PROPOSED RESOLUTION*: No.
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The memory types that don't support the handle types will simply be filtered
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out of the results returned by flink:vkGetImageMemoryRequirements and
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flink:vkGetBufferMemoryRequirements when a set of handle types was specified
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at image or buffer creation time.
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3) Should the non-opaque handle types be moved to their own extension?
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*PROPOSED RESOLUTION*: Perhaps.
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However, defining the handle type bits does very little and does not require
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any platform-specific types on its own, and it's easier to maintain the
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bitfield values in a single extension for now.
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Presumably more handle types could be added by separate extensions though,
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and it would be midly weird to have some platform-specific ones defined in
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the core spec and some in extensions
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4) Do we need a code:D3D11_TILEPOOL type?
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*PROPOSED RESOLUTION*: No.
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This is technically possible, but the synchronization is awkward.
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D3D11 surfaces must be synchronized using shared mutexes, and these
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synchronization primitives are shared by the entire memory object, so D3D11
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shared allocations divided among multiple buffer and image bindings may be
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difficult to synchronize.
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5) Should the Windows 7-compatible handle types be named "`KMT`" handles or
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"`GLOBAL_SHARE`" handles?
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*PROPOSED RESOLUTION*: KMT, simply because it is more concise.
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6) How do applications identify compatible devices and drivers across
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instance, process, and API boundaries when sharing memory?
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*PROPOSED RESOLUTION*: New device properties are exposed that allow
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applications to correctly correlate devices and drivers.
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A device and driver UUID that must both match to ensure sharing
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compatibility between two Vulkan instances, or a Vulkan instance and an
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extensible external API are added.
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To allow correlating with Direct3D devices, a device LUID is added that
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corresponds to a DXGI adapter LUID.
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A driver ID is not needed for Direct3D because mismatched driver component
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versions are not a currently supported configuration on the Windows OS.
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Should support for such configurations be introduced at the OS level,
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further Vulkan extensions would be needed to correlate userspace component
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builds.
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