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_semaphore.txt[]
 6  
 7  *Last Modified Date*::
 8      2016-10-21
 9  *IP Status*::
10      No known IP claims.
11  *Interactions and External Dependencies*::
12    - Promoted to Vulkan 1.1 Core
13  *Contributors*::
14    - Jason Ekstrand, Intel
15    - Jesse Hall, Google
16    - Tobias Hector, Imagination Technologies
17    - James Jones, NVIDIA
18    - Jeff Juliano, NVIDIA
19    - Matthew Netsch, Qualcomm Technologies, Inc.
20    - Ray Smith, ARM
21    - Chad Versace, Google
22  
23  An application using external memory may wish to synchronize access to that
24  memory using semaphores.
25  This extension enables an application to create semaphores from which
26  non-Vulkan handles that reference the underlying synchronization primitive
27  can be exported.
28  
29  === New Object Types
30  
31  None.
32  
33  === New Enum Constants
34  
35    * ename:VK_STRUCTURE_TYPE_EXPORT_SEMAPHORE_CREATE_INFO_KHR
36    * ename:VK_ERROR_INVALID_EXTERNAL_HANDLE_KHR
37  
38  === New Enums
39  
40    * elink:VkSemaphoreImportFlagBitsKHR
41  
42  === New Structs
43  
44    * slink:VkExportSemaphoreCreateInfoKHR
45  
46  === New Functions
47  
48  None.
49  
50  === Promotion to Vulkan 1.1
51  
52  All functionality in this extension is included in core Vulkan 1.1, with the
53  KHR suffix omitted.
54  The original type, enum and command names are still available as aliases of
55  the core functionality.
56  
57  === Issues
58  
59  1) Should there be restrictions on what side effects can occur when waiting
60  on imported semaphores that are in an invalid state?
61  
62  *RESOLVED*: Yes.
63  Normally, validating such state would be the responsibility of the
64  application, and the implementation would be free to enter an undefined:
65  state if valid usage rules were violated.
66  However, this could cause security concerns when using imported semaphores,
67  as it would require the importing application to trust the exporting
68  application to ensure the state is valid.
69  Requiring this level of trust is undesirable for many potential use cases.
70  
71  2) Must implementations validate external handles the application provides
72  as input to semaphore state import operations?
73  
74  *RESOLVED*: Implementations must return an error to the application if the
75  provided semaphore state handle cannot be used to complete the requested
76  import operation.
77  However, implementations need not validate handles are of the exact type
78  specified by the application.