# VK_NV_external_memory_win32(3) Manual Page

## Name

VK_NV_external_memory_win32 - device extension

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## Registered Extension Number

58

## Revision

1

## Ratification Status

Not ratified

## Extension and Version Dependencies

VK_NV_external_memory

## Deprecation State

- Deprecated by VK_KHR_external_memory_win32 extension

## Contact

- James Jones [GitHub]cubanismo

## Other Extension Metadata

Last Modified Date

  2016-08-19

IP Status

  No known IP claims.

Contributors

  - James Jones, NVIDIA

  - Carsten Rohde, NVIDIA

## Description

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 win32 applications to export win32 handles from Vulkan memory objects such that the underlying resources can be referenced outside the Vulkan instance that created them, and import win32 handles created in the Direct3D API to Vulkan memory objects.

## New Commands

- vkGetMemoryWin32HandleNV

## New Structures

- Extending VkMemoryAllocateInfo:

  - VkExportMemoryWin32HandleInfoNV

  - VkImportMemoryWin32HandleInfoNV

## New Enum Constants

- `VK_NV_EXTERNAL_MEMORY_WIN32_EXTENSION_NAME`

- `VK_NV_EXTERNAL_MEMORY_WIN32_SPEC_VERSION`

- Extending VkStructureType:

  - `VK_STRUCTURE_TYPE_EXPORT_MEMORY_WIN32_HANDLE_INFO_NV`

  - `VK_STRUCTURE_TYPE_IMPORT_MEMORY_WIN32_HANDLE_INFO_NV`

## Issues

1) If memory objects are shared between processes and APIs, is this considered aliasing according to the rules outlined in the Memory Aliasing section?

RESOLVED: 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?

RESOLVED: No. Separate instances of the same Vulkan driver running on the same GPU should have identical internal layout semantics, so applications 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 `VK_IMAGE_LAYOUT_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.

3) Do applications need to call `CloseHandle`() on the values returned from vkGetMemoryWin32HandleNV when `handleType` is `VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32_BIT_NV`?

RESOLVED: Yes, unless it is passed back in to another driver instance to import the object. A successful get call transfers ownership of the handle to the application, while an import transfers ownership to the associated driver. Destroying the memory object will not destroy the handle or the handle’s reference to the underlying memory resource.

## Examples

        //
        // Create an exportable memory object and export an external
        // handle from it.
        //

        // Pick an external format and handle type.
        static const VkFormat format = VK_FORMAT_R8G8B8A8_UNORM;
        static const VkExternalMemoryHandleTypeFlagsNV handleType =
            VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_WIN32_BIT_NV;

        extern VkPhysicalDevice physicalDevice;
        extern VkDevice device;

        VkPhysicalDeviceMemoryProperties memoryProperties;
        VkExternalImageFormatPropertiesNV properties;
        VkExternalMemoryImageCreateInfoNV externalMemoryImageCreateInfo;
        VkDedicatedAllocationImageCreateInfoNV dedicatedImageCreateInfo;
        VkImageCreateInfo imageCreateInfo;
        VkImage image;
        VkMemoryRequirements imageMemoryRequirements;
        uint32_t numMemoryTypes;
        uint32_t memoryType;
        VkExportMemoryAllocateInfoNV exportMemoryAllocateInfo;
        VkDedicatedAllocationMemoryAllocateInfoNV dedicatedAllocationInfo;
        VkMemoryAllocateInfo memoryAllocateInfo;
        VkDeviceMemory memory;
        VkResult result;
        HANDLE memoryHnd;

        // Figure out how many memory types the device supports
        vkGetPhysicalDeviceMemoryProperties(physicalDevice,
                                            &memoryProperties);
        numMemoryTypes = memoryProperties.memoryTypeCount;

        // Check the external handle type capabilities for the chosen format
        // Exportable 2D image support with at least 1 mip level, 1 array
        // layer, and VK_SAMPLE_COUNT_1_BIT using optimal tiling and supporting
        // texturing and color rendering is required.
        result = vkGetPhysicalDeviceExternalImageFormatPropertiesNV(
            physicalDevice,
            format,
            VK_IMAGE_TYPE_2D,
            VK_IMAGE_TILING_OPTIMAL,
            VK_IMAGE_USAGE_SAMPLED_BIT |
            VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT,
            0,
            handleType,
            &properties);

        if ((result != VK_SUCCESS) ||
            !(properties.externalMemoryFeatures &
              VK_EXTERNAL_MEMORY_FEATURE_EXPORTABLE_BIT_NV)) {
            abort();
        }

        // Set up the external memory image creation info
        memset(&externalMemoryImageCreateInfo,
               0, sizeof(externalMemoryImageCreateInfo));
        externalMemoryImageCreateInfo.sType =
            VK_STRUCTURE_TYPE_EXTERNAL_MEMORY_IMAGE_CREATE_INFO_NV;
        externalMemoryImageCreateInfo.handleTypes = handleType;
        if (properties.externalMemoryFeatures &
            VK_EXTERNAL_MEMORY_FEATURE_DEDICATED_ONLY_BIT_NV) {
            memset(&dedicatedImageCreateInfo, 0, sizeof(dedicatedImageCreateInfo));
            dedicatedImageCreateInfo.sType =
                VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_IMAGE_CREATE_INFO_NV;
            dedicatedImageCreateInfo.dedicatedAllocation = VK_TRUE;
            externalMemoryImageCreateInfo.pNext = &dedicatedImageCreateInfo;
        }
        // Set up the  core image creation info
        memset(&imageCreateInfo, 0, sizeof(imageCreateInfo));
        imageCreateInfo.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
        imageCreateInfo.pNext = &externalMemoryImageCreateInfo;
        imageCreateInfo.format = format;
        imageCreateInfo.extent.width = 64;
        imageCreateInfo.extent.height = 64;
        imageCreateInfo.extent.depth = 1;
        imageCreateInfo.mipLevels = 1;
        imageCreateInfo.arrayLayers = 1;
        imageCreateInfo.samples = VK_SAMPLE_COUNT_1_BIT;
        imageCreateInfo.tiling = VK_IMAGE_TILING_OPTIMAL;
        imageCreateInfo.usage = VK_IMAGE_USAGE_SAMPLED_BIT |
            VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
        imageCreateInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
        imageCreateInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;

        vkCreateImage(device, &imageCreateInfo, NULL, &image);

        vkGetImageMemoryRequirements(device,
                                     image,
                                     &imageMemoryRequirements);

        // For simplicity, just pick the first compatible memory type.
        for (memoryType = 0; memoryType < numMemoryTypes; memoryType++) {
            if ((1 << memoryType) & imageMemoryRequirements.memoryTypeBits) {
                break;
            }
        }

        // At least one memory type must be supported given the prior external
        // handle capability check.
        assert(memoryType < numMemoryTypes);

        // Allocate the external memory object.
        memset(&exportMemoryAllocateInfo, 0, sizeof(exportMemoryAllocateInfo));
        exportMemoryAllocateInfo.sType =
            VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO_NV;
        exportMemoryAllocateInfo.handleTypes = handleType;
        if (properties.externalMemoryFeatures &
            VK_EXTERNAL_MEMORY_FEATURE_DEDICATED_ONLY_BIT_NV) {
            memset(&dedicatedAllocationInfo, 0, sizeof(dedicatedAllocationInfo));
            dedicatedAllocationInfo.sType =
                VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_MEMORY_ALLOCATE_INFO_NV;
            dedicatedAllocationInfo.image = image;
            exportMemoryAllocateInfo.pNext = &dedicatedAllocationInfo;
        }
        memset(&memoryAllocateInfo, 0, sizeof(memoryAllocateInfo));
        memoryAllocateInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
        memoryAllocateInfo.pNext = &exportMemoryAllocateInfo;
        memoryAllocateInfo.allocationSize = imageMemoryRequirements.size;
        memoryAllocateInfo.memoryTypeIndex = memoryType;

        vkAllocateMemory(device, &memoryAllocateInfo, NULL, &memory);

        if (!(properties.externalMemoryFeatures &
              VK_EXTERNAL_MEMORY_FEATURE_DEDICATED_ONLY_BIT_NV)) {
            vkBindImageMemory(device, image, memory, 0);
        }

        // Get the external memory opaque FD handle
        vkGetMemoryWin32HandleNV(device, memory, &memoryHnd);

## Version History

- Revision 1, 2016-08-11 (James Jones)

  - Initial draft

## See Also

No cross-references are available

## Document Notes

For more information, see the Vulkan Specification

This page is a generated document. Fixes and changes should be made to the generator scripts, not directly.

## Copyright

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0