I have a Cube. I?ll see about updating it in the next week or two.
IIRC, the Qube doesn't have a serial port, so if you do get in to a position where you're booting without DMA disabled, it can take a good half an hour of retries to go fully multiuser.
Just a thought - does netbsd-9 try DMA and then fall back to PIO or similar?
I was running NetBSD 9 from (checking)... 2020. It ran Ultra-DMA mode 2, and I think I got a lost interrupt once in three years or so. It never fell back to PIO that I saw.
John