I should add, by the way, that this nicely demonstrates M. Geerling's point here about catching bugs by running things on a Pi.
The TianoCore's unnecessarily recursive implementation of a destructive BS is slow enough, on a Pi 4, and in combination with how the boot loaders themselves emitted their spinners, that I could just, very occasionally, see parts of spinner characters flashing very briefly on the screen when the frame refresh timing was just right; which led me to look into what was going on.
Wasn't there a post somewhere on HN yesterday about how slowing down your programs can help you catch problems? Using low end hardware is an automatic way of forcing that :)
The TianoCore's unnecessarily recursive implementation of a destructive BS is slow enough, on a Pi 4, and in combination with how the boot loaders themselves emitted their spinners, that I could just, very occasionally, see parts of spinner characters flashing very briefly on the screen when the frame refresh timing was just right; which led me to look into what was going on.