- I tested only ROLAND UM-1 and YAMAHA UX256.
These are not conforming to USB-MIDI spec, however these are
similar to USB-MIDI.
- Since I've not yet seen the "genuine" USB-MIDI device,
I cannot test such devices although I wrote the codes for it.
TODO:
- clean up the codes.
- umidi(4) manpage.
- /dev/rmidi? is working well, but /dev/music seems not working correctly.