vulkan present on Xwayland with proprietary nvidia modeset=0

[serenissi]

I observe that on intel + nvidia system booted with nvidia_drm.modeset=0 (intel is primary), vulkan apps such as vkcube running on nvidia gpu present over Xwayland on xcb wsi. In this setup however swapchain fails on wayland wsi. This is also indicated by `vkGetPhysicalDeviceSurfaceSupportKHR` and vulkaninfo:

present support:
                       VK_KHR_xcb_surface     = true
                       VK_KHR_xlib_surface    = true
                       VK_KHR_wayland_surface = false

In the case of Xwayland, bufinfo shows dmabufs created by 'drm' and attached to the intel gpu so I think intel is importing the bo. So I'm curious why without nvidia_drm.modeset enabled vulkan apps can presnt over Xwayland but fails to do so directly over the same wayland compositor Xwayland is running on. Is it something intentional by the nvidia proprietary vulkan driver or there exists some technical reason behind it?

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