1  // Copyright (c) 2016-2019 Khronos Group. This work is licensed under a
 2  // Creative Commons Attribution 4.0 International License; see
 3  // http://creativecommons.org/licenses/by/4.0/
 4  
 5  include::meta/VK_KHR_external_memory_fd.txt[]
 6  
 7  *Last Modified Date*::
 8      2016-10-21
 9  *IP Status*::
10      No known IP claims.
11  *Contributors*::
12    - James Jones, NVIDIA
13    - Jeff Juliano, NVIDIA
14  
15  An application may wish to reference device memory in multiple Vulkan
16  logical devices or instances, in multiple processes, and/or in multiple
17  APIs.
18  This extension enables an application to export POSIX file descriptor
19  handles from Vulkan memory objects and to import Vulkan memory objects from
20  POSIX file descriptor handles exported from other Vulkan memory objects or
21  from similar resources in other APIs.
22  
23  === New Object Types
24  
25  None.
26  
27  === New Enum Constants
28  
29    * ename:VK_STRUCTURE_TYPE_IMPORT_MEMORY_FD_INFO_KHR
30    * ename:VK_STRUCTURE_TYPE_MEMORY_FD_PROPERTIES_KHR
31    * ename:VK_STRUCTURE_TYPE_MEMORY_GET_FD_INFO_KHR
32  
33  === New Enums
34  
35  None.
36  
37  === New Structs
38  
39    * slink:VkImportMemoryFdInfoKHR
40    * slink:VkMemoryFdPropertiesKHR
41    * slink:VkMemoryGetFdInfoKHR
42  
43  === New Functions
44  
45    * flink:vkGetMemoryFdKHR
46    * flink:vkGetMemoryFdPropertiesKHR
47  
48  === Issues
49  
50  1) Does the application need to close the file descriptor returned by
51  flink:vkGetMemoryFdKHR?
52  
53  *RESOLVED*: Yes, unless it is passed back in to a driver instance to import
54  the memory.
55  A successful get call transfers ownership of the file descriptor to the
56  application, and a successful import transfers it back to the driver.
57  Destroying the original memory object will not close the file descriptor or
58  remove its reference to the underlying memory resource associated with it.
59  
60  2) Do drivers ever need to expose multiple file descriptors per memory
61  object?
62  
63  *RESOLVED*: No.
64  This would indicate there are actually multiple memory objects, rather than
65  a single memory object.
66  
67  3) How should the valid size and memory type for POSIX file descriptor
68  memory handles created outside of Vulkan be specified?
69  
70  *RESOLVED*: The valid memory types are queried directly from the external
71  handle.
72  The size will be specified by future extensions that introduce such external
73  memory handle types.