10.186 WFI

Wait for Interrupt.

Syntax

WFI{cond}
where:
cond
is an optional condition code.

Operation

This is a hint instruction. It is optional whether this instruction is implemented or not. If this instruction is not implemented, it executes as a NOP. The assembler produces a diagnostic message if the instruction executes as a NOP on the target.
WFI executes as a NOP instruction in ARMv6T2.
WFI suspends execution until one of the following events occurs:
  • An IRQ interrupt, regardless of the CPSR I-bit.
  • An FIQ interrupt, regardless of the CPSR F-bit.
  • An Imprecise Data abort, unless masked by the CPSR A-bit.
  • A Debug Entry request, regardless of whether Debug is enabled.

Architectures

This ARM instruction is available in ARMv6K and above.
This 32-bit Thumb instruction is available in ARMv6T2 and above.
This 16-bit Thumb instruction is available in ARMv6T2 and above.
Related reference
10.67 NOP
10.8 Condition code suffixes
10.185 WFE
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