Arm® A64 Instruction Set Architecture: Future Architecture Technologies in the A architecture profile

WFIT

Wait For Interrupt 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. For more information, see Wait For Interrupt.

As described in Wait For Interrupt, the execution of a WFIT 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.

System
(Armv8.7)

if !HaveFeatWFxT() then UNDEFINED;

integer d = UInt(Rd);

Assembler Symbols

bits(64) operand = X[d];
integer localtimeout = UInt(operand);

if Halted() && ConstrainUnpredictableBool(Unpredictable_WFxTDEBUG) then
    EndOfInstruction();

Hint_WFI(localtimeout);