RADV Vulkan Driver Now Exposes VK_EXT_external_memory_host

RADV, the Mesa Radeon Vulkan driver, now has external memory host support via the VK_EXT_external_memory_host extension that was recently introduced in the Vulkan 1.0.66 update.

VK_EXT_external_memory_host allows an application/game to import host allocations and host-mapped foreign device memory that in turn becomes Vulkan memory objects. The VK_EXT_external_memory_host extension was developed by AMD as well as Intel, NVIDIA, and other companies.

Independent Mesa contributor Fredrik Höglund has added support for this extension. He managed this by basing the code off RadeonSI's AMD_pinned_memory implementation. OpenGL's AMD_pinned_memory allows system memory from the application/game to be used as memory directly accessible to the GPU. It's similar enough in nature to VK_EXT_external_memory_host that it appears to have been an easy add.