This is my first contribution to QEMU: I've written a virtual piece of
hardware (e.g. ports) that the mouse pointer can be used as an absolute
pointing device even with non USB devices, e.g. with DOS and doesn't need
any high memory usage USB driver. This is necessary for e.g. VNC remote
access, this was my primary motivation.
Why not just use the existing vmmouse?
To use it you need a mouse driver (e.g. cutemouse,
http://cutemouse.sourceforge.net/) and an QEMU mouse TSR.
Further the mouse TSR emulates also a HP-HIL 45911 tablet digitizer. This
device has been chosen because an Interrupt interface exists at INT 6Fh and
therefore it is relativly easy to emulate (all other devices I've evaluated
use the serial port and are therefore much more complex to emulate)
However emulating an actual tablet connected to the serial port means you
don't need any custom guest software.