wfi

Wait For Interrupt

WFI

Puts the processor into a low-power state until an interrupt occurs.

Pseudocode Operation

# Enter low-power state
while (no_interrupt_pending) do
  wait_for_interrupt
PC ← PC + 4

Encoding

Binary Layout

11010101000000110010

31:12

0000

11:8

011

7:5

11111

4:0

Format System Alias

Opcode 0xD503207F

Extension Base

Operands

Other forms of wfi

wfi Wait For Interrupt (A32)
wfi Wait For Interrupt (Thumb)

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD503207F	WFI		A64		11010101000000110010 \| 0000 \| 011 \| 11111

Description

Wait For Interrupt is a hint instruction that indicates that the PE can enter a low-power state and remain there until a wakeup event occurs. For more information, see Wait For Interrupt. As described in Wait For Interrupt, the execution of a WFI instruction that would otherwise cause entry to a low-power state can be trapped to a higher Exception level.

Operation

integer localtimeout = 1 << 64;    // No local timeout event is generated
Hint_WFI(localtimeout, WFxType_WFI);

wfi