Hi, I'm working on a project that requires porting my KEXT driver to DriverKit system extension ( DEXT ). I've managed to re-write most of functions using DriverKit but I couldn't found a function for cancelling a scheduled timer. What I try to make is waiting for an interrupt with a timeout period. And if the interrupt arrives in certain time period I need to cancel timeout timer and send async response to the user app. I'm also open to the suggestions. Here is the code fragment for IOKit that I need to convert to DriverKit // ... initialization code fragment ( error handling parts deleted ) m_timeout_timer = IOTimerEventSource::timerEventSource(this, timer_fired_pc_recv); IOReturn result = m_workLoop->addEventSource(timer); // ... starting the timeout counter m_timeout_timer->setTimeoutMS(timeout_in_ms); // ... some time later (cancel part) m_timeout_timer->cancelTimeout(); And equivalent code in DriverKit // ... initialization code fragment ( error handling parts deleted ) ret = IOTimerDispatchSource::Create(ivars->default_dispatch_queue, &ivars->timer_dispatchSource); // starting timer timer_dispatchSource->WakeAtTime(kIOTimerClockMonotonicRaw, currentTime + fiveSecondsInNanoSeconds, twoSecondsInNanoSeconds); // missing part here I did see the member method Cancel in IOTimerDispatchSource but it is kind of termination to the lifetime of IOTimerDispatchSource