C Specification

To determine the dedicated allocation requirements of a buffer or image resource, add a VkMemoryDedicatedRequirements structure to the pNext chain of the VkMemoryRequirements2 structure passed as the pMemoryRequirements parameter of vkGetBufferMemoryRequirements2 or vkGetImageMemoryRequirements2.

The VkMemoryDedicatedRequirements structure is defined as:

typedef struct VkMemoryDedicatedRequirements {
    VkStructureType    sType;
    void*              pNext;
    VkBool32           prefersDedicatedAllocation;
    VkBool32           requiresDedicatedAllocation;
} VkMemoryDedicatedRequirements;

or the equivalent

typedef VkMemoryDedicatedRequirements VkMemoryDedicatedRequirementsKHR;

Members

  • sType is the type of this structure.

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

  • prefersDedicatedAllocation specifies that the implementation would prefer a dedicated allocation for this resource. The application is still free to suballocate the resource but it may get better performance if a dedicated allocation is used.

  • requiresDedicatedAllocation specifies that a dedicated allocation is required for this resource.

Description

When the implementation sets requiresDedicatedAllocation to VK_TRUE, it must also set prefersDedicatedAllocation to VK_TRUE.

If the VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed as the pMemoryRequirements parameter of a vkGetBufferMemoryRequirements2 call, requiresDedicatedAllocation may be VK_TRUE under one of the following conditions:

  • The pNext chain of VkBufferCreateInfo for the call to vkCreateBuffer used to create the buffer being queried contained an instance of VkExternalMemoryBufferCreateInfo, and any of the handle types specified in VkExternalMemoryBufferCreateInfo::handleTypes requires dedicated allocation, as reported by vkGetPhysicalDeviceExternalBufferProperties in VkExternalBufferProperties::externalMemoryProperties::externalMemoryFeatures, the requiresDedicatedAllocation field will be set to VK_TRUE.

In all other cases, requiresDedicatedAllocation must be set to VK_FALSE by the implementation whenever a VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed to a call to vkGetBufferMemoryRequirements2.

If the VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed as the pMemoryRequirements parameter of a vkGetBufferMemoryRequirements2 call and VK_BUFFER_CREATE_SPARSE_BINDING_BIT was set in VkBufferCreateInfo::flags when buffer was created then the implementation must set both prefersDedicatedAllocation and requiresDedicatedAllocation to VK_FALSE.

If the VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed as the pMemoryRequirements parameter of a vkGetImageMemoryRequirements2 call, requiresDedicatedAllocation may be VK_TRUE under one of the following conditions:

  • The pNext chain of VkImageCreateInfo for the call to vkCreateImage used to create the image being queried contained an instance of VkExternalMemoryImageCreateInfo, and any of the handle types specified in VkExternalMemoryImageCreateInfo::handleTypes requires dedicated allocation, as reported by vkGetPhysicalDeviceImageFormatProperties2 in VkExternalImageFormatProperties::externalMemoryProperties::externalMemoryFeatures, the requiresDedicatedAllocation field will be set to VK_TRUE.

In all other cases, requiresDedicatedAllocation must be set to VK_FALSE by the implementation whenever a VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed to a call to vkGetImageMemoryRequirements2.

If the VkMemoryDedicatedRequirements structure is included in the pNext chain of the VkMemoryRequirements2 structure passed as the pMemoryRequirements parameter of a vkGetImageMemoryRequirements2 call and VK_IMAGE_CREATE_SPARSE_BINDING_BIT was set in VkImageCreateInfo::flags when image was created then the implementation must set both prefersDedicatedAllocation and requiresDedicatedAllocation to VK_FALSE.

Valid Usage (Implicit)
  • sType must be VK_STRUCTURE_TYPE_MEMORY_DEDICATED_REQUIREMENTS

See Also

VkBool32, 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 (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.