Vulkan-Docs/doc/specs/vulkan/appendices/VK_NV_external_memory.txt

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[[VK_NV_external_memory]]
== VK_NV_external_memory
*Name String*::
+VK_NV_external_memory+
*Extension Type*::
Device extension
*Registered Extension Number*::
57
*Status*::
Complete
*Last Modified Date*::
2016-08-19
*Revision*::
1
*IP Status*::
No known IP claims.
*Dependencies*::
- This extension is written against version 1.0 of the Vulkan API.
- Requires +VK_NV_external_memory_capabilities+
*Contributors*::
- James Jones, NVIDIA
- Carsten Rohde, NVIDIA
*Contact*::
- James Jones (jajones 'at' nvidia.com)
Applications may wish to export memory to other Vulkan instances or other
APIs, or import memory from other Vulkan instances or other APIs to enable
Vulkan workloads to be split up across application module, process, or API
boundaries.
This extension enables applications to create exportable Vulkan memory
objects such that the underlying resources can be referenced outside the
Vulkan instance that created them.
=== New Object Types
None.
=== New Enum Constants
Extending elink:VkStructureType:
** ename:VK_STRUCTURE_TYPE_EXTERNAL_MEMORY_IMAGE_CREATE_INFO_NV
** ename:VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO_NV
=== New Enums
None.
=== New Structures
* Extending slink:VkImageCreateInfo:
** slink:VkExternalMemoryImageCreateInfoNV
* Extending slink:VkMemoryAllocateInfo
** slink:VkExportMemoryAllocateInfoNV
=== New Functions
None.
=== Issues
1) If memory objects are shared between processes and APIs, is this
considered aliasing according to the rules outlined in section 11.8,
Memory Aliasing?
RESOLUTION: Yes, but strict exceptions to the rules are added to allow
some forms of aliasing in these cases.
Further, other extensions may build upon these new aliasing rules to
define specific support usage within Vulkan for imported native memory
objects, or memory objects from other APIs.
2) Are new image layouts or metadata required to specify image layouts and
layout transitions compatible with non-Vulkan APIs, or with other
instances of the same Vulkan driver?
RESOLUTION: No.
Separate instances of the same Vulkan driver running on the same GPU
should have identical internal layout semantics, so applictions have the
tools they need to ensure views of images are consistent between the two
instances.
Other APIs will fall into two categories: Those that are Vulkan-
compatible (A term to be defined by subsequent interopability
extensions), or Vulkan incompatible.
When sharing images with Vulkan incompatible APIs, the Vulkan image must
be transitioned to the GENERAL layout before handing it off to the
external API.
Note this does not attempt to address cross-device transitions, nor
transitions to engines on the same device which are not visible within
the Vulkan API.
Both of these are beyond the scope of this extension.
=== Examples
[source,{basebackend@docbook:c++:cpp}]
----------------------------------------
// TODO: Write some sample code here.
----------------------------------------
=== Version History
* Revision 1, 2016-08-19 (James Jones)
- Initial draft