[SeaBIOS] Add support for legacy USB keyboard/mouse (PS/2 emulation for USB?)

[Gerd Hoffmann]

  Hi,

> initialize their own USB HID driver. I'm not using QEMU's emulated USB
> HID devices, because I utilize VGA passthrough, so I need direct
> access from guest machine.

Better use the emulated ps/2 devices.

Starting with qemu 2.6 qemu can read input events directly from linux
evdev devices.  With older versions you have to use a dummy sdl/gtk/vnc
device to feed qemu with input events.

cheers,
  Gerd