VkMemoryAllocateInfo

The VkMemoryAllocateInfo structure is defined as:

typedef struct VkMemoryAllocateInfo {
    VkStructureType sType;
    const void* pNext;
    VkDeviceSize allocationSize;
    uint32_t memoryTypeIndex;
} VkMemoryAllocateInfo;

• sType is a VkStructureType value identifying this structure.
• pNext is NULL or a pointer to a structure extending this structure.
• allocationSize is the size of the allocation in bytes.
• memoryTypeIndex is an index identifying a memory type from the memoryTypes array of the VkPhysicalDeviceMemoryProperties structure.

The internal data of an allocated device memory object must include a reference to implementation-specific resources, referred to as the memory object’s payload. Applications can also import and export that internal data to and from device memory objects to share data between Vulkan instances and other compatible APIs. A VkMemoryAllocateInfo structure defines a memory import operation if its pNext chain includes one of the following structures:

• VkImportMemoryWin32HandleInfoKHR with a non-zero handleType value
• VkImportMemoryFdInfoKHR with a non-zero handleType value
• VkImportMemoryHostPointerInfoEXT with a non-zero handleType value
• VkImportAndroidHardwareBufferInfoANDROID with a non-NULL
buffer value
• VkImportMemoryZirconHandleInfoFUCHSIA with a non-zero handleType value
• VkImportMemoryBufferCollectionFUCHSIA
• VkImportScreenBufferInfoQNX with a non-NULL buffer value

If the parameters define an import operation and the external handle type is VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_BIT, VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_KMT_BIT, or VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D12_RESOURCE_BIT, allocationSize is ignored. The implementation must query the size of these allocations from the OS.

Whether device memory objects constructed via a memory import operation hold a reference to their payload depends on the properties of the handle type used to perform the import, as defined below for each valid handle type. Importing memory must not modify the content of the memory. Implementations must ensure that importing memory does not enable the importing Vulkan instance to access any memory or resources in other Vulkan instances other than that corresponding to the memory object imported. Implementations must also ensure accessing imported memory which has not been initialized does not allow the importing Vulkan instance to obtain data from the exporting Vulkan instance or vice-versa.

Importing memory must not increase overall heap usage within a system. However, it must affect the following per-process values:

• VkPhysicalDeviceLimits::maxMemoryAllocationCount
• VkPhysicalDeviceMemoryBudgetPropertiesEXT::heapUsage

When performing a memory import operation, it is the responsibility of the application to ensure the external handles and their associated payloads meet all valid usage requirements. However, implementations must perform sufficient validation of external handles and payloads to ensure that the operation results in a valid memory object which will not cause program termination, device loss, queue stalls, or corruption of other resources when used as allowed according to its allocation parameters. If the external handle provided does not meet these requirements, the implementation must fail the memory import operation with the error code VK_ERROR_INVALID_EXTERNAL_HANDLE. If the parameters define an export operation and the external handle type is VK_EXTERNAL_MEMORY_HANDLE_TYPE_ANDROID_HARDWARE_BUFFER_BIT_ANDROID, implementations should not strictly follow memoryTypeIndex. Instead, they should modify the allocation internally to use the required memory type for the application’s given usage. This is because for an export operation, there is currently no way for the application to know the memory type index before allocating.