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 GetBufferDeviceAddress with a VkBuffer, it will return a VkDeviceAddress value which represents the address of the start of the buffer.

GetBufferOpaqueCaptureAddress and GetDeviceMemoryOpaqueCaptureAddress 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.

There are various use cases this extension is designed for. It is required for ray tracing, useful for DX12 portability, and by allowing buffer addresses to be stored in memory it enables more complex data structures to be created.

This extension can also be used to hardcode a dedicated debug channel into all shaders by querying a pointer at startup and pushing that into shaders as a run-time constant (e.g. specialization constant) that avoids impacting other descriptor limits.

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 also added to help cover a few additional edge cases.

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.

VK_KHR_buffer_device_address

Name String

VK_KHR_buffer_device_address

Extension Type

Device extension

Registered Extension Number

258

Revision

1

Extension and Version Dependencies

VK_KHR_get_physical_device_properties2      and      VK_KHR_device_group or Version 1.1

Deprecation state

• Promoted to Vulkan 1.2

Contact

• Jeff Bolz jeffbolznv

Other Extension Metadata

Last Modified Date

2019-06-24

IP Status

No known IP claims.

Interactions and External Dependencies

• Promoted to Vulkan 1.2 Core
• This extension requires SPV_KHR_physical_storage_buffer
• 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