Safe Haskell	Safe-Inferred
Language	Haskell2010

Vulkan.Extensions.VK_KHR_buffer_device_address

Description

Name

VK_KHR_buffer_device_address - device extension

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

Requires support for Vulkan 1.0
Requires VK_KHR_get_physical_device_properties2 to be enabled for any device-level functionality

Deprecation state

Promoted to Vulkan 1.2

Contact

Jeff Bolz @jeffbolznv%0A*Here describe the issue or question you have about the VK_KHR_buffer_device_address extension*

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
Jason 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 getBufferDeviceAddress with a Buffer, it will return a DeviceAddress 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.