3 ms·
It's almost certainly a hack based on system management mode. Not sure how it does it, but SMM is even used to emulate the PS/2 keyboard interface (at I/O ports
by bonzini 5y ago
It's almost certainly a hack based on system management mode. Not sure how it does it, but SMM is even used to emulate the PS/2 keyboard interface (at I/O ports 0x60/0x61) when all you have is a USB keyboard. So it's likely that the chipset has some kind of "backdoor" to the USB controller that can be accessed from SMM.