loader: Add documentation fo loader handling of VK_surface_*KHR extensions.
Document the special handling og vkSurfaceKHR objects.
diff --git a/loader/README.md b/loader/README.md
index b8840d2..24f9558 100644
--- a/loader/README.md
+++ b/loader/README.md
@@ -28,7 +28,12 @@
- vkEnumerateInstanceExtensionProperties exported
- vkGetDeviceProcAddr exported and returns valid function pointers for all the VK API entrypoints
- vkGetInstanceProcAddr exported and returns valid function pointers for all the VK API entrypoints
-- all objects created by ICD can be cast to (VK\_LAYER\_DISPATCH\_TABLE \*\*)
+- WSI surface extensions (vk_KHR_*surface) handling:
+ 1. Loader handles the vkCreate*SurfaceKHR() and vkDestroySurfaceKHR() functions including creating/destroying the VkSurfaceKHR object
+ 2. VkSurfaceKHR objects have the underlying structure (VKIcdSurface*) as defined in include/vulkan/vk_icd.h
+ 3. ICDs can cast any VkSurfaceKHR object to a pointer to the appropriate VKIcdSurface* structure
+ 4. VkIcdSurface* structures include VkIcdSurfaceWin32, VkIcdSurfaceXcb, VkIcdSurfaceXlib, VkIcdSurfaceMir, and VkIcdSurfaceWayland
+- all objects created by an ICD can be cast to (VK\_LAYER\_DISPATCH\_TABLE \*\*)
where the loader will replace the first entry with a pointer to the dispatch table which is
owned by the loader. This implies three things for ICD drivers:
1. The ICD must return a pointer for the opaque object handle