Wait For Event with Timeout is a hint instruction that indicates that the PE can enter a low-power state and remain there until either a local timeout event or a wakeup event occurs. Wakeup events include the event signaled as a result of executing the SEV instruction on any PE in the multiprocessor system. For more information, see Wait For Event mechanism and Send event.
As described in Wait For Event mechanism and Send event, the execution of a WFET instruction that would otherwise cause entry to a low-power state can be trapped to a higher Exception level. See:
- Traps to EL1 of EL0 execution of WFE and WFI instructions.
- Traps to EL2 of Non-secure EL0 and EL1 execution of WFE and WFI instructions.
- Traps to EL3 of EL2, EL1, and EL0 execution of WFE and WFI instructions.
if !HaveFeatWFxT() then UNDEFINED; integer d = UInt(Rd);