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vulkan

Why are some Vulkan extensions available through dynamic linking, but not others?

I've been trying to write Vulkan bindings for a language and I'm a bit confused about how extensions work. On Linux I'm using libdl to load function pointers from libvulkan.so.1, and I've noticed that some extension functions (like those from VK_KHR_swapchain and VK_KHR_Wayland_Surface) can be linked through libdl, but others (like the ones in VK_EXT_debug_utils or VK_EXT_extended_dynamic_state2) can only be found through vkGetInstanceProcAddr or vkGetDeviceProcAddr.

My questions are these:

  1. Why are some Vulkan extensions available through dynamic linking but not others?
  2. Can I rely on these dynamically-linkable extensions always being there? (For example, can I be sure that if the VK_KHR_swapchain extension is available, vkCreateSwapchainKHR will definitly be found by libdl?)
Solution

  • TFM:

    Vulkan Direct Exports

    The loader library on Windows, Linux, Android, and macOS will export all core Vulkan entry-points and all appropriate Window System Interface (WSI) entry-points. This is done to make it simpler to get started with Vulkan development. When an application links directly to the loader library in this way, the Vulkan calls are simple trampoline functions that jump to the appropriate dispatch table entry for the object they are given.

    Specifics: https://github.com/KhronosGroup/Vulkan-Loader/blob/main/docs/LoaderApplicationInterface.md#wsi-extensions