VK_KHR_buffer_device_address

Other Extension Metadata

Last Modified Date

2019-06-24

IP Status

No known IP claims.

Interactions and External Dependencies

• This extension provides API support for GL_EXT_buffer_reference and GL_EXT_buffer_reference2 and GL_EXT_buffer_reference_uvec2

Contributors

• Jeff Bolz, NVIDIA
• Neil Henning, AMD
• Tobias Hector, AMD
• Faith Ekstrand, Intel
• Baldur Karlsson, Valve
• Jan-Harald Fredriksen, Arm

Description

This extension allows the application to query a 64-bit buffer device address value for a buffer, which can be used to access the buffer memory via the PhysicalStorageBuffer storage class in the GL_EXT_buffer_reference GLSL extension and SPV_KHR_physical_storage_buffer SPIR-V extension.

Another way to describe this extension is that it adds pointers to buffer memory in shaders. By calling vkGetBufferDeviceAddress with a VkBuffer, it will return a VkDeviceAddress value which represents the address of the start of the buffer.

vkGetBufferOpaqueCaptureAddress and vkGetDeviceMemoryOpaqueCaptureAddress allow opaque addresses for buffers and memory objects to be queried for the current process. A trace capture and replay tool can then supply these addresses to be used at replay time to match the addresses used when the trace was captured. To enable tools to insert these queries, new memory allocation flags must be specified for memory objects that will be bound to buffers accessed via the PhysicalStorageBuffer storage class. Note that this mechanism is intended only to support capture/replay tools, and is not recommended for use in other applications.

Promotion to Vulkan 1.2

All functionality in this extension is included in core Vulkan 1.2, with the KHR suffix omitted. However, if Vulkan 1.2 is supported and this extension is not, the bufferDeviceAddress feature is optional. The original type, enum, and command names are still available as aliases of the core functionality.

Promotion to Vulkan 1.3

Support for the bufferDeviceAddress feature is mandatory in Vulkan 1.3, regardless of whether this extension is supported.

New Commands

• vkGetBufferDeviceAddressKHR
• vkGetBufferOpaqueCaptureAddressKHR
• vkGetDeviceMemoryOpaqueCaptureAddressKHR

New Structures

• VkBufferDeviceAddressInfoKHR
• VkDeviceMemoryOpaqueCaptureAddressInfoKHR
• Extending VkBufferCreateInfo:
  • VkBufferOpaqueCaptureAddressCreateInfoKHR
• Extending VkMemoryAllocateInfo:
  • VkMemoryOpaqueCaptureAddressAllocateInfoKHR
• Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:
  • VkPhysicalDeviceBufferDeviceAddressFeaturesKHR

New Enum Constants

• VK_KHR_BUFFER_DEVICE_ADDRESS_EXTENSION_NAME
• VK_KHR_BUFFER_DEVICE_ADDRESS_SPEC_VERSION
• Extending VkBufferCreateFlagBits:
  • VK_BUFFER_CREATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT_KHR
• Extending VkBufferUsageFlagBits:
  • VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT_KHR
• Extending VkMemoryAllocateFlagBits:
  • VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT_KHR
  • VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_CAPTURE_REPLAY_BIT_KHR
• Extending VkResult:
  • VK_ERROR_INVALID_OPAQUE_CAPTURE_ADDRESS_KHR
• Extending VkStructureType:
  • VK_STRUCTURE_TYPE_BUFFER_DEVICE_ADDRESS_INFO_KHR
  • VK_STRUCTURE_TYPE_BUFFER_OPAQUE_CAPTURE_ADDRESS_CREATE_INFO_KHR
  • VK_STRUCTURE_TYPE_DEVICE_MEMORY_OPAQUE_CAPTURE_ADDRESS_INFO_KHR
  • VK_STRUCTURE_TYPE_MEMORY_OPAQUE_CAPTURE_ADDRESS_ALLOCATE_INFO_KHR
  • VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_BUFFER_DEVICE_ADDRESS_FEATURES_KHR

New SPIR-V Capabilities

• PhysicalStorageBufferAddresses

Examples

There are various use cases this extensions is designed for. It is required for ray tracing, useful for DX12 portability, and it allows storing buffer addresses in memory (enabling creating more complex data structures).

This extension can also be used to hardcode a dedicated debug channel into all shaders without impacting other descriptor limits by querying a buffer device address at startup and pushing that into shaders as a runtime constant (e.g. specialization constant).

There are examples of usage in the GL_EXT_buffer_reference spec for how to use this in a high-level shading language such as GLSL. The GL_EXT_buffer_reference2 and GL_EXT_buffer_reference_uvec2 extensions were added to help cover a few edge cases missed by the original GL_EXT_buffer_reference.

Version History

• Revision 1, 2019-06-24 (Jan-Harald Fredriksen)
  • Internal revisions based on VK_EXT_buffer_device_address