VK_KHR_external_memory_fd

Other Extension Metadata

Last Modified Date

2016-10-21

IP Status

No known IP claims.

Contributors

• James Jones, NVIDIA
• Jeff Juliano, NVIDIA

Description

An application may wish to reference device memory in multiple Vulkan logical devices or instances, in multiple processes, and/or in multiple APIs. This extension enables an application to export POSIX file descriptor handles from Vulkan memory objects and to import Vulkan memory objects from POSIX file descriptor handles exported from other Vulkan memory objects or from similar resources in other APIs.

New Commands

• vkGetMemoryFdKHR
• vkGetMemoryFdPropertiesKHR

New Structures

• VkMemoryFdPropertiesKHR
• VkMemoryGetFdInfoKHR
• Extending VkMemoryAllocateInfo:
  • VkImportMemoryFdInfoKHR

New Enum Constants

• VK_KHR_EXTERNAL_MEMORY_FD_EXTENSION_NAME
• VK_KHR_EXTERNAL_MEMORY_FD_SPEC_VERSION
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_IMPORT_MEMORY_FD_INFO_KHR
  • VK_STRUCTURE_TYPE_MEMORY_FD_PROPERTIES_KHR
  • VK_STRUCTURE_TYPE_MEMORY_GET_FD_INFO_KHR

Issues

1) Does the application need to close the file descriptor returned by vkGetMemoryFdKHR?

RESOLVED: Yes, unless it is passed back in to a driver instance to import the memory. A successful get call transfers ownership of the file descriptor to the application, and a successful import transfers it back to the driver. Destroying the original memory object will not close the file descriptor or remove its reference to the underlying memory resource associated with it.

2) Do drivers ever need to expose multiple file descriptors per memory object?

RESOLVED: No. This would indicate there are actually multiple memory objects, rather than a single memory object.

3) How should the valid size and memory type for POSIX file descriptor memory handles created outside of Vulkan be specified?

RESOLVED: The valid memory types are queried directly from the external handle. The size will be specified by future extensions that introduce such external memory handle types.

Version History

• Revision 1, 2016-10-21 (James Jones)
  • Initial revision