"Does my GPU need to talk to my mouse"? That is definitely one of those "it depends on the system". On at least one DECStation model, sort of (depending on how

"Does my GPU need to talk to my mouse"? That is definitely one of those "it depends on the system". On at least one DECStation model, sort of (depending on how you define "GPU"), the mouse interface is actually on the graphics card, and is read by the CPU talking to the graphics hardware. When they're running the DEC-provided X11 server, the mouse pointer moving on screen is done entirely within the graphics subsystem, with no need to talk to the kernel. Which leads to the hilarity of wiggling the mouse actually not being a good diagnostic for "has the kernel hung itself", as the mouse pointer will wiggle (but clicking doing nothing, and usually not changing shape as you'd expect as it goes over fields where you'd expect that).