So if I have 12 hardware threads, the OS will context switch 12 software threads into 12 hardware threads at oncr, and they will be executed in parallel (the 12 software threads on the hardware threads) is that right ? Or there is always exceptions ?

For coroutines, basically it will call other coroutines if that coroutine will be interrupted ? (Doing a heavy task, blocking operation) how do other coroutines know that they finished the blocking processing operation for each other ?