How does u-boot under openmoko-qemu receive keyboard event?

[wei zheng]

Hi guys,

         When I press "enter" key of my PC keyboard,  menu of u-boot running
on the openmoko-qemu emulator will move down. But I don't know how the
u-boot receives the keyboard event. Is the event received from serial? From
touch-screen? Which files are the related codes in?