VK_KHR_buffer_device_address.md

VK_KHR_buffer_device_address

Promoted to core in Vulkan 1.2

Formerly VK_EXT_buffer_device_address

SPV_KHR_physical_storage_buffer

GLSL - GL_EXT_buffer_reference, GLSL - GL_EXT_buffer_reference2, and GLSL - GL_EXT_buffer_reference_uvec2

Note for people creating tools or autogenerating from the registry, the vkGetBufferDeviceAddress does not return VkResult or void like most API calls

This extension can be summarized as "adding pointers in shaders". It adds a new PhysicalStorageBuffer64 addressing mode in SPIR-V and a way to query a 64-bit buffer device address via the new SPIR-V PhysicalStorageBuffer storage class. By calling vkGetBufferDeviceAddress with the VkBuffer to query it will return a VkDeviceAddress object which represents the device buffer address value. With GPUs hitting over 4GB of device memory this extension becomes important for use cases where 32-bit address space is not big enough.

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.

Tracing and Capturing

This extension also allows the ability for trace capture and reply tools to use the addresses for more advance tooling purposes. These hooks to device memory for tooling are labeled as opaqueCaptureAddress. This is "the sharpest of razors to control the hardware" and is only designed for things such as tooling and is highly recommended to not attempt to use these to ship production applications.