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Enabling buffer device address

Device extension VK_KHR_buffer_device_address allow to fetch raw GPU pointer to a buffer and pass it for usage in a shader code. It has been promoted to core Vulkan 1.2.

If you want to use this feature in connection with VMA, follow these steps:

# Initialization

1) (For Vulkan version < 1.2) Call vkEnumerateDeviceExtensionProperties for the physical device. Check if the extension is supported - if returned array of VkExtensionProperties contains "VK_KHR_buffer_device_address".

2) Call vkGetPhysicalDeviceFeatures2 for the physical device instead of old vkGetPhysicalDeviceFeatures. Attach additional structure VkPhysicalDeviceBufferDeviceAddressFeatures* to VkPhysicalDeviceFeatures2::pNext to be returned. Check if the device feature is really supported - check if VkPhysicalDeviceBufferDeviceAddressFeatures::bufferDeviceAddress is true.

3) (For Vulkan version < 1.2) While creating device with vkCreateDevice, enable this extension - add "VK_KHR_buffer_device_address" to the list passed as VkDeviceCreateInfo::ppEnabledExtensionNames.

4) While creating the device, also don't set VkDeviceCreateInfo::pEnabledFeatures. Fill in VkPhysicalDeviceFeatures2 structure instead and pass it as VkDeviceCreateInfo::pNext. Enable this device feature - attach additional structure VkPhysicalDeviceBufferDeviceAddressFeatures* to VkPhysicalDeviceFeatures2::pNext and set its member bufferDeviceAddress to VK_TRUE.

5) While creating VmaAllocator with vmaCreateAllocator() inform VMA that you have enabled this feature - add VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT to VmaAllocatorCreateInfo::flags.

# Usage

After following steps described above, you can create buffers with VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT* using VMA. The library automatically adds VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT* to allocated memory blocks wherever it might be needed.

Please note that the library supports only VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT*. The second part of this functionality related to "capture and replay" is not supported, as it is intended for usage in debugging tools like RenderDoc, not in everyday Vulkan usage.

# More information

To learn more about this extension, see VK_KHR_buffer_device_address in Vulkan specification

Example use of this extension can be found in the code of the sample and test suite accompanying this library.