Enable instance extensions in MoltenVK

Question

I'd like to make use of the supported extensions in MoltenVK 1.0.38, at the moment there are 47 which are printed when you initialize an instance of Vulkan. Funny thing is when I call vkEnumerateInstanceExtensionProperties, I only get 9 of them:

VK_KHR_device_group_creation
VK_KHR_get_physical_device_properties2
VK_KHR_get_surface_capabilities2
VK_KHR_surface
VK_EXT_debug_report
VK_EXT_debug_utils
VK_EXT_metal_surface
VK_EXT_swapchain_colorspace
VK_MVK_macos_surface

Am particularly interested in VK_EXT_hdr_metadata, but that one doesn't show up in this list. Here is the full list of the supported extensions that MoltenVK says it supports, but are not available to me:

    The following 47 Vulkan extensions are supported:
        VK_KHR_16bit_storage v1
        VK_KHR_8bit_storage v1
        VK_KHR_bind_memory2 v1
        VK_KHR_dedicated_allocation v3
        VK_KHR_descriptor_update_template v1
        VK_KHR_device_group v4
        VK_KHR_device_group_creation v1
        VK_KHR_get_memory_requirements2 v1
        VK_KHR_get_physical_device_properties2 v2
        VK_KHR_get_surface_capabilities2 v1
        VK_KHR_image_format_list v1
        VK_KHR_maintenance1 v2
        VK_KHR_maintenance2 v1
        VK_KHR_maintenance3 v1
        VK_KHR_push_descriptor v2
        VK_KHR_relaxed_block_layout v1
        VK_KHR_sampler_mirror_clamp_to_edge v3
        VK_KHR_shader_draw_parameters v1
        VK_KHR_shader_float16_int8 v1
        VK_KHR_storage_buffer_storage_class v1
        VK_KHR_surface v25
        VK_KHR_swapchain v70
        VK_KHR_swapchain_mutable_format v1
        VK_KHR_uniform_buffer_standard_layout v1
        VK_KHR_variable_pointers v1
        VK_EXT_debug_marker v4
        VK_EXT_debug_report v9
        VK_EXT_debug_utils v1
        VK_EXT_fragment_shader_interlock v1
        VK_EXT_hdr_metadata v2
        VK_EXT_host_query_reset v1
        VK_EXT_memory_budget v1
        VK_EXT_metal_surface v1
        VK_EXT_scalar_block_layout v1
        VK_EXT_shader_stencil_export v1
        VK_EXT_shader_viewport_index_layer v1
        VK_EXT_swapchain_colorspace v4
        VK_EXT_texel_buffer_alignment v1
        VK_EXT_vertex_attribute_divisor v3
        VK_EXTX_portability_subset v1
        VK_MVK_macos_surface v2
        VK_MVK_moltenvk v22
        VK_AMD_gpu_shader_half_float v2
        VK_AMD_negative_viewport_height v1
        VK_AMD_shader_trinary_minmax v1
        VK_INTEL_shader_integer_functions2 v1
        VK_NV_glsl_shader v1

Answer 1

VK_EXT_hdr_metadata is a device extension, and would show up only in vkEnumerateDeviceExtensionProperties output.