Am Dienstag, 8. September 2015, 22:40:07 schrieb Dmitry Torokhov:
Hi Dmitry,
>
>All input devices add randomness, however I think for mouse
>add_input_randomness() will drop majority of events since they are
>likely have the same value (well, depends on which direction you are
>moving the mouse)...
I agree that such mechanism is present, but it is implemented by
add_input_randomness:
/* ignore autorepeat and the like */
if (value == last_value)
return;
So, when we install a probe at the entry into add_input_randomness, we should
see invocations.
The problem now is that add_input_randomness is not called at all.
Simply use the following code as a systemtap script, load it and move a USB
mouse or type on a USB keyboard:
probe kernel.function("add_input_randomness") {
printf("add_input_randomness triggered\n");
}
Expected behavior: tons of printouts should be received (as it is the case
with PS/2 mice and keyboards).
Actual behavior: no printout when moving USB HID.
Ciao
Stephan
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