I have an EZ-USB AN21xx device and I'm trying to do overlapped i/o for the DeviceIoControl call and it is performing ...

Question: Does EZUSB.sys support overlapped I/O?

 

Answer:

The ezusb.sys driver is a synchronous driver and does not support overlapped I/O.

So for example if  overlapping I/O for the DeviceIOControl call is called (in an EZ-USB AN21xx device) and it performs CreateFile calls with the file overlapped flag. The problem will be that the code in DeviceIOControl never exits, even though it is called with the overlapped I/O flag.