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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:
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op2 |
WFET <Xt>
if !HaveFeatWFxT() then UNDEFINED; integer d = UInt(Rd); SystemHintOp op; case op2 of when '000' op = SystemHintOp_WFET; when '001' op = SystemHintOp_WFIT; otherwise // Do nothing
bits(64) operand = X[d];
integer localtimeout = UInt(operand);
if Halted() && ConstrainUnpredictableBool(Unpredictable_WFxTDEBUG) then
EndOfInstruction();
case op of
when SystemHintOp_WFETHint_WFE(localtimeout,(localtimeout);
when WFxType_WFET);
when SystemHintOp_WFITHint_WFI(localtimeout, WFxType_WFIT);
(localtimeout);
otherwise
// Instruction executes as NOP
Internal version only: isa v32.13v32.12, AdvSIMD v29.05v29.04, pseudocode v2020-12v2020-09_xml, sve v2020-12v2020-09_rc2b
; Build timestamp: 2020-12-16T142020-09-30T19:4116
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