<?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="AT_SYS" title="AT -- A64" type="alias">
  <docvars>
    <docvar key="alias_mnemonic" value="AT"/>
    <docvar key="instr-class" value="system"/>
    <docvar key="isa" value="A64"/>
    <docvar key="mnemonic" value="SYS"/>
  </docvars>
  <heading>AT</heading>
  <desc>
    <brief>
      <para>Address translate</para>
    </brief>
    <authored>
      <para>For more information, see
<xref linkend="ARMARM_BABEJJJE">op0 == 0b01, cache maintenance, TLB maintenance, address translation, prediction restriction,
BRBE, Trace Extension, and Guarded Control Stack instructions</xref>.</para>
    </authored>
  </desc>
  <aliasto refiform="sys.xml" iformid="SYS">SYS</aliasto>
  <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="SYS"/>
      </docvars>
      <iclassintro count="1"/>
      <regdiagram form="32" psname="A64.control.systeminstrs.SYS_CR_systeminstrs.AT" 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="4" settings="4">
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="21" name="L" usename="1" settings="1" psbits="x">
          <c>0</c>
        </box>
        <box hibit="20" width="2" settings="2">
          <c>0</c>
          <c>1</c>
        </box>
        <box hibit="18" width="3" name="op1" usename="1">
          <c colspan="3"/>
        </box>
        <box hibit="15" width="4" name="CRn" usename="1" settings="4" psbits="xxxx">
          <c>0</c>
          <c>1</c>
          <c>1</c>
          <c>1</c>
        </box>
        <box hibit="11" width="4" name="CRm" usename="1" settings="3" psbits="xxxx">
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>x</c>
        </box>
        <box hibit="7" width="3" name="op2" usename="1">
          <c colspan="3"/>
        </box>
        <box hibit="4" width="5" name="Rt" usename="1">
          <c colspan="5"/>
        </box>
      </regdiagram>
      <encoding name="AT_SYS_CR_systeminstrs" oneofinclass="1" oneof="1" label="">
        <docvars>
          <docvar key="instr-class" value="system"/>
          <docvar key="isa" value="A64"/>
          <docvar key="mnemonic" value="SYS"/>
          <docvar key="alias_mnemonic" value="AT"/>
        </docvars>
        <asmtemplate><text>AT  </text><a hover="Is an AT operation name, as listed for the AT system instruction group, " link="at_op_option">&lt;at_op&gt;</a><text>, </text><a hover="Is the 64-bit name of the general-purpose source register, encoded in the &quot;Rt&quot; field." link="XtOrXZR__3">&lt;Xt&gt;</a></asmtemplate>
        <equivalent_to>
          <asmtemplate><a href="sys.xml#SYS_CR_systeminstrs">SYS</a><text>  #</text><a hover="Is a 3-bit unsigned immediate, in the range 0 to 7, encoded in the &quot;op1&quot; field." href="sys.xml#op1">&lt;op1&gt;</a><text>, C7, </text><a hover="Is a name 'Cm', with 'm' in the range 0 to 15, encoded in the &quot;CRm&quot; field." href="sys.xml#Cm">&lt;Cm&gt;</a><text>, #</text><a hover="Is a 3-bit unsigned immediate, in the range 0 to 7, encoded in the &quot;op2&quot; field." href="sys.xml#op2">&lt;op2&gt;</a><text>, </text><a hover="Is the 64-bit name of the optional general-purpose source register, defaulting to '11111', encoded in the &quot;Rt&quot; field." href="sys.xml#XtOrXZR__2">&lt;Xt&gt;</a></asmtemplate>
          <aliascond>SysOp(op1, '0111', CRm, op2) == Sys_AT</aliascond>
        </equivalent_to>
      </encoding>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="AT_SYS_CR_systeminstrs" symboldefcount="1">
      <symbol link="at_op_option">&lt;at_op&gt;</symbol>
      <definition encodedin="(op1 :: CRm :: op2)">
        <intro>Is an AT operation name, as listed for the AT system instruction group, </intro>
        <table class="valuetable">
          <tgroup cols="6">
            <thead>
              <row>
                <entry class="bitfield">op1</entry>
                <entry class="bitfield">CRm</entry>
                <entry class="bitfield">op2</entry>
                <entry class="symbol">&lt;at_op&gt;</entry>
                <entry class="symbol">Architectural Feature</entry>
                <entry class="symbol">Description</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">000</entry>
                <entry class="symbol">S1E1R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e1r.xml" state="AArch64">AT S1E1R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">001</entry>
                <entry class="symbol">S1E1W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e1w.xml" state="AArch64">AT S1E1W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">010</entry>
                <entry class="symbol">S1E0R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e0r.xml" state="AArch64">AT S1E0R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">011</entry>
                <entry class="symbol">S1E0W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e0w.xml" state="AArch64">AT S1E0W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1001</entry>
                <entry class="bitfield">000</entry>
                <entry class="symbol">S1E1RP</entry>
                <entry class="feature">
                  <arch_variants>
                    <arch_variant feature="FEAT_PAN2"/>
                  </arch_variants>
                </entry>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e1rp.xml" state="AArch64">AT S1E1RP</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1001</entry>
                <entry class="bitfield">001</entry>
                <entry class="symbol">S1E1WP</entry>
                <entry class="feature">
                  <arch_variants>
                    <arch_variant feature="FEAT_PAN2"/>
                  </arch_variants>
                </entry>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e1wp.xml" state="AArch64">AT S1E1WP</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">000</entry>
                <entry class="bitfield">1001</entry>
                <entry class="bitfield">010</entry>
                <entry class="symbol">S1E1A</entry>
                <entry class="feature">
                  <arch_variants>
                    <arch_variant feature="FEAT_ATS1A"/>
                  </arch_variants>
                </entry>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e1a.xml" state="AArch64">AT S1E1A</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">000</entry>
                <entry class="symbol">S1E2R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e2r.xml" state="AArch64">AT S1E2R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">001</entry>
                <entry class="symbol">S1E2W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e2w.xml" state="AArch64">AT S1E2W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">100</entry>
                <entry class="symbol">S12E1R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s12e1r.xml" state="AArch64">AT S12E1R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">101</entry>
                <entry class="symbol">S12E1W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s12e1w.xml" state="AArch64">AT S12E1W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">110</entry>
                <entry class="symbol">S12E0R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s12e0r.xml" state="AArch64">AT S12E0R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">111</entry>
                <entry class="symbol">S12E0W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s12e0w.xml" state="AArch64">AT S12E0W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">100</entry>
                <entry class="bitfield">1001</entry>
                <entry class="bitfield">010</entry>
                <entry class="symbol">S1E2A</entry>
                <entry class="feature">
                  <arch_variants>
                    <arch_variant feature="FEAT_ATS1A"/>
                  </arch_variants>
                </entry>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e2a.xml" state="AArch64">AT S1E2A</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">110</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">000</entry>
                <entry class="symbol">S1E3R</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e3r.xml" state="AArch64">AT S1E3R</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">110</entry>
                <entry class="bitfield">1000</entry>
                <entry class="bitfield">001</entry>
                <entry class="symbol">S1E3W</entry>
                <entry class="feature"/>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e3w.xml" state="AArch64">AT S1E3W</register_link>.</para>
                </entry>
              </row>
              <row>
                <entry class="bitfield">110</entry>
                <entry class="bitfield">1001</entry>
                <entry class="bitfield">010</entry>
                <entry class="symbol">S1E3A</entry>
                <entry class="feature">
                  <arch_variants>
                    <arch_variant feature="FEAT_ATS1A"/>
                  </arch_variants>
                </entry>
                <entry class="description">
                  <para>For more information, see <register_link id="AArch64-at-s1e3a.xml" state="AArch64">AT S1E3A</register_link>.</para>
                </entry>
              </row>
            </tbody>
          </tgroup>
        </table>
      </definition>
    </explanation>
    <explanation enclist="AT_SYS_CR_systeminstrs" symboldefcount="1">
      <symbol link="XtOrXZR__3">&lt;Xt&gt;</symbol>
      <account encodedin="Rt">
        <intro>
          <para>Is the 64-bit name of the general-purpose source register, encoded in the &quot;Rt&quot; field.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <timestamp>2026-03-26 20:27:25</timestamp>
  <commit_id>2026-03_rel</commit_id>
</instructionsection>