111 lines
3.4 KiB
Plaintext
111 lines
3.4 KiB
Plaintext
include::meta/VK_EXT_external_memory_host.txt[]
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*Last Modified Date*::
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2017-11-10
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*IP Status*::
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No known IP claims.
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*Contributors*::
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- Jaakko Konttinen, AMD
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- David Mao, AMD
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- Daniel Rakos, AMD
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- Tobias Hector, Imagination Technologies
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- Jason Ekstrand, Intel
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- James Jones, NVIDIA
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This extension enables an application to import host allocations and host
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mapped foreign device memory to Vulkan memory objects.
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=== New Object Types
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None.
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=== New Enum Constants
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* Extending elink:VkStructureType:
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** ename:VK_STRUCTURE_TYPE_IMPORT_MEMORY_HOST_POINTER_INFO_EXT
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** ename:VK_STRUCTURE_TYPE_MEMORY_HOST_POINTER_PROPERTIES_EXT
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_MEMORY_HOST_PROPERTIES_EXT
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* Extending elink:VkExternalMemoryHandleTypeFlagBitsKHR:
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** ename:VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_ALLOCATION_BIT_EXT
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** ename:VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_MAPPED_FOREIGN_MEMORY_BIT_EXT
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=== New Enums
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None.
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=== New Structs
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* slink:VkImportMemoryHostPointerInfoEXT
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* slink:VkMemoryHostPointerPropertiesEXT
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* slink:VkPhysicalDeviceExternalMemoryHostPropertiesEXT
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=== New Functions
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* flink:vkGetMemoryHostPointerPropertiesEXT
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=== Issues
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1) What memory type has to be used to import host pointers?
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RESOLVED: Depends on the implementation.
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Applications have to use the new flink:vkGetMemoryHostPointerPropertiesEXT
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command to query the supported memory types for a particular host pointer.
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The reported memory types may include memory types that come from a memory
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heap that is otherwise not usable for regular memory object allocation and
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thus such a heap's size may be zero.
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2) Can the application still access the contents of the host allocation
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after importing?
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RESOLVED: Yes.
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However, usual synchronization requirements apply.
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3) Can the application free the host allocation?
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RESOLVED: No, it violates valid usage conditions.
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Using the memory object imported from a host allocation that's already freed
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thus results in undefined behavior.
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4) Is flink:vkMapMemory expected to return the same host address which was
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specified when importing it to the memory object?
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RESOLVED: No.
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Implementations are allowed to return the same address but it's not
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required.
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Some implementations might return a different virtual mapping of the
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allocation, although the same physical pages will be used.
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5) Is there any limitation on the alignment of the host pointer and/or size?
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RESOLVED: Yes.
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Both the address and the size have to be an integer multiple of
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pname:minImportedHostPointerAlignment.
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In addition, some platforms and foreign devices may have additional
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restrictions.
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6) Can the same host allocation be imported multiple times into a given
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physical device?
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RESOLVED: No, at least not guaranteed by this extension.
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Some platforms do not allow locking the same physical pages for device
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access multiple times, so attempting to do it may result in undefined
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behavior.
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7) Does this extension support exporting the new handle type?
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RESOLVED: No.
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8) Should we include the possibility to import host mapped foreign device
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memory using this API?
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RESOLVED: Yes, through a separate handle type.
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Implementations are still allowed to support only one of the handle types
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introduced by this extension by not returning import support for a
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particular handle type as returned in slink:VkExternalMemoryPropertiesKHR.
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=== Version History
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* Revision 1, 2017-11-10 (Daniel Rakos)
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- Internal revisions
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