On a GPU without KGSL, Setup offers an experimental Mali bridge switch
(off by default; ignored on Adreno). With it on, the session starts the
bridge server, points the Vulkan loader at the bridge ICD, names Mali's
device as the stand-in render node, runs the bridge self-test into the
session log, and caps vkd3d-proton's feature level at 12_0. Flatpak
sandboxes get the bridge ICD and socket. The DRM preload falls back to
flock in a bridge session when kcmp is refused, and a clock/thermal log
is kept beside the bridge logs.