# VkImportMemoryHostPointerInfoEXT(3) Manual Page

## Name

VkImportMemoryHostPointerInfoEXT - import memory from a host pointer

## C Specification

To import memory from a host pointer, add a VkImportMemoryHostPointerInfoEXT structure to the `pNext` chain of the VkMemoryAllocateInfo structure. The `VkImportMemoryHostPointerInfoEXT` structure is defined as:

    typedef struct VkImportMemoryHostPointerInfoEXT {
        VkStructureType                       sType;
        const void*                           pNext;
        VkExternalMemoryHandleTypeFlagBits    handleType;
        void*                                 pHostPointer;
    } VkImportMemoryHostPointerInfoEXT;

## Members

- `sType` is the type of this structure.

- `pNext` is `NULL` or a pointer to an extension-specific structure.

- `handleType` specifies the handle type.

- `pHostPointer` is the host pointer to import from.

## Description

Importing memory from a host pointer shares ownership of the memory between the host and the Vulkan implementation. The application can continue to access the memory through the host pointer but it is the application’s responsibility to synchronize device and non-device access to the underlying memory as defined in Host Access to Device Memory Objects.

Applications can import the same underlying memory into multiple instances of Vulkan and multiple times into a given Vulkan instance. However, implementations may fail to import the same underlying memory multiple times into a given physical device due to platform constraints.

Importing memory from a particular host pointer may not be possible due to additional platform-specific restrictions beyond the scope of this specification in which case the implementation must fail the memory import operation with the error code `VK_ERROR_INVALID_EXTERNAL_HANDLE_KHR`.

The application must ensure that the imported memory range remains valid and accessible for the lifetime of the imported memory object.

Valid Usage

- If `handleType` is not `0`, it must be supported for import, as reported in VkExternalMemoryProperties

- If `handleType` is not `0`, it must be `VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_ALLOCATION_BIT_EXT` or `VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_MAPPED_FOREIGN_MEMORY_BIT_EXT`

- `pHostPointer` must be a pointer aligned to an integer multiple of `VkPhysicalDeviceExternalMemoryHostPropertiesEXT`::`minImportedHostPointerAlignment`

- If `handleType` is `VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_ALLOCATION_BIT_EXT`, `pHostPointer` must be a pointer to `allocationSize` number of bytes of host memory, where `allocationSize` is the member of the `VkMemoryAllocateInfo` structure this structure is chained to

- If `handleType` is `VK_EXTERNAL_MEMORY_HANDLE_TYPE_HOST_MAPPED_FOREIGN_MEMORY_BIT_EXT`, `pHostPointer` must be a pointer to `allocationSize` number of bytes of host mapped foreign memory, where `allocationSize` is the member of the `VkMemoryAllocateInfo` structure this structure is chained to

Valid Usage (Implicit)

- `sType` must be `VK_STRUCTURE_TYPE_IMPORT_MEMORY_HOST_POINTER_INFO_EXT`

- `handleType` must be a valid VkExternalMemoryHandleTypeFlagBits value

## See Also

VkExternalMemoryHandleTypeFlagBits, VkStructureType

## Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright (c) 2014-2020 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.