<?xml version="1.0" ?><?xml-stylesheet type="text/xsl" encoding="UTF-8" href="iform.xsl" version="1.0"?><!DOCTYPE instructionsection  PUBLIC '-//ARM//DTD instructionsection //EN'  'iform-p.dtd'><!-- Copyright (c) 2010-2026 Arm Limited or its affiliates. All rights reserved. --><!-- This document is Non-Confidential. This document may only be used and distributed in accordance with the terms of the agreement entered into by Arm and the party that Arm delivered this document to. --><instructionsection id="WFE" title="WFE -- A64" type="instruction">
  <docvars>
    <docvar key="instr-class" value="system"/>
    <docvar key="isa" value="A64"/>
    <docvar key="mnemonic" value="WFE"/>
  </docvars>
  <heading>WFE</heading>
  <desc>
    <brief>
      <para>Wait for event</para>
    </brief>
    <authored>
      <para>This instruction is a hint instruction that indicates that the PE can
enter a low-power state and remain there until a wakeup event
occurs. Wakeup events include the event signaled as a result of
executing the <instruction>SEV</instruction> instruction on any PE in the multiprocessor
system.
For more information, see <xref linkend="ARMARM_BEIJHBBD">Wait For Event
mechanism and Send event</xref>.</para>
      <para>As described in <xref linkend="ARMARM_BEIJHBBD">Wait For Event mechanism and Send event</xref>, the
execution of a <instruction>WFE</instruction> instruction that would otherwise cause entry to a low-power
state can be trapped to a higher Exception level.</para>
    </authored>
  </desc>
  <alias_list howmany="0"/>
  <classes>
    <iclass name="System" oneof="1" id="iclass_system" no_encodings="1" isa="A64">
      <docvars>
        <docvar key="instr-class" value="system"/>
        <docvar key="isa" value="A64"/>
        <docvar key="mnemonic" value="WFE"/>
      </docvars>
      <iclassintro count="1"/>
      <regdiagram form="32" psname="A64.control.hints.WFE_HI_hints" tworows="1">
        <box hibit="31" width="3" settings="3">
          <c>1</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="28" width="3" settings="3">
          <c>1</c>
          <c>0</c>
          <c>1</c>
        </box>
        <box hibit="25" width="14" settings="14">
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="11" width="4" name="CRm" usename="1" settings="4" psbits="xxxx">
          <c>0</c>
          <c>0</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="7" width="3" name="op2" usename="1" settings="3" psbits="xxx">
          <c>0</c>
          <c>1</c>
          <c>0</c>
        </box>
        <box hibit="4" width="5" settings="5">
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
        </box>
      </regdiagram>
      <encoding name="WFE_HI_hints" oneofinclass="1" oneof="1" label="">
        <docvars>
          <docvar key="instr-class" value="system"/>
          <docvar key="isa" value="A64"/>
          <docvar key="mnemonic" value="WFE"/>
        </docvars>
        <asmtemplate><text>WFE</text></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="A64.control.hints.WFE_HI_hints" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">// Empty.</pstext></ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all"/>
  <ps_section howmany="1">
    <ps name="A64.control.hints.WFE_HI_hints" sections="1" secttype="Operation">
      <pstext mayhavelinks="1" section="Execute" rep_section="execute"><a link="func_Hint_WFE_0" file="shared_pseudocode.xml">Hint_WFE</a>();</pstext></ps>
  </ps_section>
  <timestamp>2026-03-26 20:27:25</timestamp>
  <commit_id>2026-03_rel</commit_id>
</instructionsection>