path: root/static/freebsd/man4/acpi.4 3.html

<table class="head">
  <tr>
    <td class="head-ltitle">ACPI(4)</td>
    <td class="head-vol">Device Drivers Manual</td>
    <td class="head-rtitle">ACPI(4)</td>
  </tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">acpi</code> &#x2014; <span class="Nd">Advanced
    Configuration and Power Management support</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">device acpi</code></p>
<p class="Pp">
  <br/>
  <code class="Cd">options ACPI_DEBUG</code>
  <br/>
  <code class="Cd">options DDB</code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">acpi</code> driver provides support for the
    Intel/Microsoft/Compaq/Toshiba ACPI standard. This support includes platform
    hardware discovery (superseding the PnP and PCI BIOS), as well as power
    management (superseding APM) and other features. ACPI core support is
    provided by the ACPI CA reference implementation from Intel.</p>
<p class="Pp">Note that the <code class="Nm">acpi</code> driver is automatically
    loaded by the <a class="Xr">loader(8)</a>, and should only be compiled into
    the kernel on platforms where ACPI is mandatory.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYSCTL_VARIABLES"><a class="permalink" href="#SYSCTL_VARIABLES">SYSCTL
  VARIABLES</a></h1>
<p class="Pp">The <code class="Nm">acpi</code> driver is intended to provide
    power management without user intervention. If the default settings are not
    optimal, the following sysctls can be used to modify or monitor
    <code class="Nm">acpi</code> behavior. Note that some variables will be
    available only if the given hardware supports them (such as
    <var class="Va">hw.acpi.acline</var>).</p>
<dl class="Bl-tag">
  <dt id="debug.acpi.enable_debug_objects"><var class="Va">debug.acpi.enable_debug_objects</var></dt>
  <dd>Enable dumping Debug objects without <code class="Cd">options
      ACPI_DEBUG</code>. Default is 0, ignore Debug objects.</dd>
  <dt id="dev.cpu.N.cx_usage"><var class="Va">dev.cpu.N.cx_usage</var></dt>
  <dd>Debugging information listing the percent of total usage for each sleep
      state. The values are reset when <var class="Va">dev.cpu.N.cx_lowest</var>
      is modified.</dd>
  <dt id="dev.cpu.N.cx_lowest"><var class="Va">dev.cpu.N.cx_lowest</var></dt>
  <dd>Lowest Cx state to use for idling the CPU. A scheduling algorithm will
      select states between <code class="Li">C1</code> and this setting as
      system load dictates. To enable ACPI CPU idling control,
      <var class="Va">machdep.idle</var> should be set to
      <code class="Li">acpi</code> if it is listed in
      <var class="Va">machdep.idle_available</var>.</dd>
  <dt id="dev.cpu.N.cx_supported"><var class="Va">dev.cpu.N.cx_supported</var></dt>
  <dd>List of supported CPU idle states and their transition latency in
      microseconds. Each state has a type (e.g., <code class="Li">C2</code>).
      <code class="Li">C1</code> is equivalent to the ia32
      <code class="Li">HLT</code> instruction, <code class="Li">C2</code>
      provides a deeper sleep with the same semantics, and
      <code class="Li">C3</code> provides the deepest sleep but additionally
      requires bus mastering to be disabled. States greater than
      <code class="Li">C3</code> provide even more power savings with the same
      semantics as the <code class="Li">C3</code> state. Deeper sleeps provide
      more power savings but increased transition latency when an interrupt
      occurs.</dd>
  <dt id="dev.cpu.N.cx_method"><var class="Va">dev.cpu.N.cx_method</var></dt>
  <dd>List of supported CPU idle states and their transition methods, as
      directed by the firmware.</dd>
  <dt id="hw.acpi.acline"><var class="Va">hw.acpi.acline</var></dt>
  <dd>AC line state (1 means online, 0 means on battery power).</dd>
  <dt id="hw.acpi.disable_on_reboot"><var class="Va">hw.acpi.disable_on_reboot</var></dt>
  <dd>Disable ACPI during the reboot process. Most systems reboot fine with ACPI
      still enabled, but some require exiting to legacy mode first. Default is
      0, leave ACPI enabled.</dd>
  <dt id="hw.acpi.handle_reboot"><var class="Va">hw.acpi.handle_reboot</var></dt>
  <dd>Use the ACPI Reset Register capability to reboot the system. Some newer
      systems require use of this register, while some only work with legacy
      rebooting support.</dd>
  <dt id="hw.acpi.lid_switch_state"><var class="Va">hw.acpi.lid_switch_state</var></dt>
  <dd>Sleep type (<code class="Li">awake</code>,
      <code class="Li">standby</code>, <code class="Li">s2mem</code>,
      <code class="Li">s2idle</code>, <code class="Li">hibernate</code>,
      <code class="Li">poweroff</code>) to enter when the lid switch (i.e., a
      notebook screen) is closed, or
      &#x201C;<code class="Li">NONE</code>&#x201D; (do nothing). Default is
      &#x201C;<code class="Li">NONE</code>&#x201D;.</dd>
  <dt id="hw.acpi.power_button_state"><var class="Va">hw.acpi.power_button_state</var></dt>
  <dd>Sleep type (<code class="Li">awake</code>,
      <code class="Li">standby</code>, <code class="Li">s2mem</code>,
      <code class="Li">s2idle</code>, <code class="Li">hibernate</code>,
      <code class="Li">poweroff</code>) to enter when the power button is
      pressed, or &#x201C;<code class="Li">NONE</code>&#x201D; (do nothing).
      Default is <code class="Li">poweroff</code>.</dd>
  <dt id="hw.acpi.reset_video"><var class="Va">hw.acpi.reset_video</var></dt>
  <dd>Reset the video adapter from real mode during the resume path. Some
      systems need this help, others have display problems if it is enabled.
      Default is 0 (disabled).</dd>
  <dt id="hw.acpi.s4bios"><var class="Va">hw.acpi.s4bios</var></dt>
  <dd>Indicate whether the system supports <code class="Li">S4BIOS</code>. This
      means that the BIOS can handle all the functions of suspending the system
      to disk. Otherwise, the OS is responsible for suspending to disk
      (<code class="Li">S4OS</code>). Most current systems do not support
      <code class="Li">S4BIOS</code>.</dd>
  <dt id="hw.acpi.sleep_button_state"><var class="Va">hw.acpi.sleep_button_state</var></dt>
  <dd>Sleep type (<code class="Li">awake</code>,
      <code class="Li">standby</code>, <code class="Li">s2mem</code>,
      <code class="Li">s2idle</code>, <code class="Li">hibernate</code>,
      <code class="Li">poweroff</code>) to enter when the sleep button is
      pressed. This is usually a special function button on the keyboard.
      Default is usually <code class="Li">s2mem</code> if supported, and
      <code class="Li">s2idle</code> if not.</dd>
  <dt id="hw.acpi.sleep_delay"><var class="Va">hw.acpi.sleep_delay</var></dt>
  <dd>Wait this number of seconds between preparing the system to suspend and
      actually entering the suspend state. Default is 1 second.</dd>
  <dt id="hw.acpi.supported_sleep_state"><var class="Va">hw.acpi.supported_sleep_state</var></dt>
  <dd>ACPI S-states
      (<code class="Li">S1</code>&#x2013;<code class="Li">S5</code>) supported
      by the BIOS.
    <dl class="Bl-tag">
      <dt id="S1"><a class="permalink" href="#S1"><code class="Li">S1</code></a></dt>
      <dd>Quick suspend to RAM. The CPU enters a lower power state, but most
          peripherals are left running.</dd>
      <dt id="S2"><a class="permalink" href="#S2"><code class="Li">S2</code></a></dt>
      <dd>Lower power state than <code class="Li">S1</code>, but with the same
          basic characteristics. Not supported by many systems.</dd>
      <dt id="S3"><a class="permalink" href="#S3"><code class="Li">S3</code></a></dt>
      <dd>Suspend to RAM. Most devices are powered off, and the system stops
          running except for memory refresh.</dd>
      <dt id="S4"><a class="permalink" href="#S4"><code class="Li">S4</code></a></dt>
      <dd>Suspend to disk. All devices are powered off, and the system stops
          running. When resuming, the system starts as if from a cold power on.
          Not yet supported by <span class="Ux">FreeBSD</span> unless
          <code class="Li">S4BIOS</code> is available.</dd>
      <dt id="S5"><a class="permalink" href="#S5"><code class="Li">S5</code></a></dt>
      <dd>System shuts down cleanly and powers off.</dd>
    </dl>
  </dd>
  <dt id="hw.acpi.verbose"><var class="Va">hw.acpi.verbose</var></dt>
  <dd>Enable verbose printing from the various ACPI subsystems.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="LOADER_TUNABLES"><a class="permalink" href="#LOADER_TUNABLES">LOADER
  TUNABLES</a></h1>
<p class="Pp">Tunables can be set at the <a class="Xr">loader(8)</a> prompt
    before booting the kernel or stored in
    <span class="Pa">/boot/loader.conf</span>. Many of these tunables also have
    a matching <a class="Xr">sysctl(8)</a> entry for access after boot.</p>
<dl class="Bl-tag">
  <dt id="acpi_dsdt_load"><var class="Va">acpi_dsdt_load</var></dt>
  <dd>Enables loading of a custom ACPI DSDT.</dd>
  <dt id="acpi_dsdt_name"><var class="Va">acpi_dsdt_name</var></dt>
  <dd>Name of the DSDT table to load, if loading is enabled.</dd>
  <dt id="debug.acpi.disabled"><var class="Va">debug.acpi.disabled</var></dt>
  <dd>Selectively disables portions of ACPI for debugging purposes.</dd>
  <dt id="debug.acpi.interpreter_slack"><var class="Va">debug.acpi.interpreter_slack</var></dt>
  <dd>Enable less strict ACPI implementations. Default is 1, ignore common BIOS
      mistakes.</dd>
  <dt id="debug.acpi.max_threads"><var class="Va">debug.acpi.max_threads</var></dt>
  <dd>Specify the number of task threads that are started on boot. Limiting this
      to 1 may help work around various BIOSes that cannot handle parallel
      requests. The default value is 3.</dd>
  <dt id="debug.acpi.quirks"><var class="Va">debug.acpi.quirks</var></dt>
  <dd>Override any automatic quirks completely.</dd>
  <dt id="debug.acpi.resume_beep"><var class="Va">debug.acpi.resume_beep</var></dt>
  <dd>Beep the PC speaker on resume. This can help diagnose suspend/resume
      problems. Default is 0 (disabled).</dd>
  <dt id="hint.acpi.0.disabled"><var class="Va">hint.acpi.0.disabled</var></dt>
  <dd>Set this to 1 to disable all of ACPI. If ACPI has been disabled on your
      system due to a blacklist entry for your BIOS, you can set this to 0 to
      re-enable ACPI for testing.</dd>
  <dt id="hw.acpi.ec.poll_timeout"><var class="Va">hw.acpi.ec.poll_timeout</var></dt>
  <dd>Delay in milliseconds to wait for the EC to respond. Try increasing this
      number if you get the error
      &quot;<code class="Li">AE_NO_HARDWARE_RESPONSE</code>&quot;.</dd>
  <dt id="hw.acpi.host_mem_start"><var class="Va">hw.acpi.host_mem_start</var></dt>
  <dd>Override the assumed memory starting address for PCI host bridges.</dd>
  <dt id="hw.acpi.install_interface"><var class="Va">hw.acpi.install_interface</var>,
    <var class="Va">hw.acpi.remove_interface</var></dt>
  <dd>Install or remove OS interface(s) to control return value of
      &#x2018;<code class="Li">_OSI</code>&#x2019; query method. When an OS
      interface is specified in <var class="Va">hw.acpi.install_interface</var>,
      <code class="Li">_OSI</code> query for the interface returns it is
      <a class="permalink" href="#supported"><i class="Em" id="supported">supported</i></a>.
      Conversely, when an OS interface is specified in
      <var class="Va">hw.acpi.remove_interface</var>,
      <code class="Li">_OSI</code> query returns it is
      <a class="permalink" href="#not"><i class="Em" id="not">not
      supported</i></a>. Multiple interfaces can be specified in a
      comma-separated list and any leading white spaces will be ignored. For
      example, &quot;<code class="Li">FreeBSD, Linux</code>&quot; is a valid
      list of two interfaces &quot;<code class="Li">FreeBSD</code>&quot; and
      &quot;<code class="Li">Linux</code>&quot;.</dd>
  <dt id="hw.acpi.hw.acpi.override_isa_irq_polarity"><var class="Va">hw.acpi.hw.acpi.override_isa_irq_polarity
    (x86)</var></dt>
  <dd>Forces active-lo polarity for edge-triggered ISA interrupts. Some older
      systems incorrectly specify active-lo polarity for ISA interrupts and this
      override fixes those systems. This override is enabled by default on
      systems with Intel CPUs, but can be enabled or disabled by setting the
      tunable explicitly.</dd>
  <dt id="hw.acpi.reset_video~2"><var class="Va">hw.acpi.reset_video</var></dt>
  <dd>Enables calling the VESA reset BIOS vector on the resume path. This can
      fix some graphics cards that have problems such as LCD white-out after
      resume. Default is 0 (disabled).</dd>
  <dt id="hw.acpi.serialize_methods"><var class="Va">hw.acpi.serialize_methods</var></dt>
  <dd>Allow override of whether methods execute in parallel or not. Enable this
      for serial behavior, which fixes
      &quot;<code class="Li">AE_ALREADY_EXISTS</code>&quot; errors for AML that
      really cannot handle parallel method execution. It is off by default since
      this breaks recursive methods and some IBMs use such code.</dd>
  <dt id="hw.acpi.verbose~2"><var class="Va">hw.acpi.verbose</var></dt>
  <dd>Turn on verbose debugging information about what ACPI is doing.</dd>
  <dt id="hw.pci.link._s._d.irq"><var class="Va">hw.pci.link.%s.%d.irq</var></dt>
  <dd>Override the interrupt to use for this link and index. This capability
      should be used carefully, and only if a device is not working with
      <code class="Nm">acpi</code> enabled. &quot;%s&quot; is the name of the
      link (e.g., LNKA). &quot;%d&quot; is the resource index when the link
      supports multiple IRQs. Most PCI links only have one IRQ resource, so the
      below form should be used.</dd>
  <dt id="hw.pci.link._s.irq"><var class="Va">hw.pci.link.%s.irq</var></dt>
  <dd>Override the interrupt to use. This capability should be used carefully,
      and only if a device is not working with <code class="Nm">acpi</code>
      enabled. &quot;%s&quot; is the name of the link (e.g., LNKA).</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="DISABLING_ACPI"><a class="permalink" href="#DISABLING_ACPI">DISABLING
  ACPI</a></h1>
<p class="Pp">Since ACPI support on different platforms varies greatly, there
    are many debugging and tuning options available.</p>
<p class="Pp">For machines known not to work with <code class="Nm">acpi</code>
    enabled, there is a BIOS blacklist. Currently, the blacklist only controls
    whether <code class="Nm">acpi</code> should be disabled or not. In the
    future, it will have more granularity to control features (the
    infrastructure for that is already there).</p>
<p class="Pp">To enable <code class="Nm">acpi</code> (for debugging purposes,
    etc.) on machines that are on the blacklist, set the kernel environment
    variable <var class="Va">hint.acpi.0.disabled</var> to 0. Before trying
    this, consider updating your BIOS to a more recent version that may be
    compatible with ACPI.</p>
<p class="Pp">To disable the <code class="Nm">acpi</code> driver completely, set
    the kernel environment variable <var class="Va">hint.acpi.0.disabled</var>
    to 1.</p>
<p class="Pp">Some i386 machines totally fail to operate with some or all of
    ACPI disabled. Other i386 machines fail with ACPI enabled. Disabling all or
    part of ACPI on non-i386 platforms (i.e., platforms where ACPI support is
    mandatory) may result in a non-functional system.</p>
<p class="Pp">The <code class="Nm">acpi</code> driver comprises a set of
    drivers, which may be selectively disabled in case of problems. To disable a
    sub-driver, list it in the kernel environment variable
    <var class="Va">debug.acpi.disabled</var>. Multiple entries can be listed,
    separated by a space.</p>
<p class="Pp">ACPI sub-devices and features that can be disabled:</p>
<dl class="Bl-tag">
  <dt id="all"><a class="permalink" href="#all"><code class="Li">all</code></a></dt>
  <dd>Disable all ACPI features and devices.</dd>
  <dt id="acad"><a class="permalink" href="#acad"><code class="Li">acad</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports AC adapter.</dd>
  <dt id="bus"><a class="permalink" href="#bus"><code class="Li">bus</code></a></dt>
  <dd>(<var class="Vt">feature</var>) Probes and attaches subdevices. Disabling
      will avoid scanning the ACPI namespace entirely.</dd>
  <dt id="children"><a class="permalink" href="#children"><code class="Li">children</code></a></dt>
  <dd>(<var class="Vt">feature</var>) Attaches standard ACPI sub-drivers and
      devices enumerated in the ACPI namespace. Disabling this has a similar
      effect to disabling &#x201C;<code class="Li">bus</code>&#x201D;, except
      that the ACPI namespace will still be scanned.</dd>
  <dt id="button"><a class="permalink" href="#button"><code class="Li">button</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports ACPI button devices (typically
      power and sleep buttons).</dd>
  <dt id="cmbat"><a class="permalink" href="#cmbat"><code class="Li">cmbat</code></a></dt>
  <dd>(<var class="Vt">device</var>) Control-method batteries device.</dd>
  <dt id="cpu"><a class="permalink" href="#cpu"><code class="Li">cpu</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports CPU power-saving and speed-setting
      functions.</dd>
  <dt id="ec"><a class="permalink" href="#ec"><code class="Li">ec</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports the ACPI Embedded Controller
      interface, used to communicate with embedded platform controllers.</dd>
  <dt id="isa"><a class="permalink" href="#isa"><code class="Li">isa</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports an ISA bus bridge defined in the
      ACPI namespace, typically as a child of a PCI bus.</dd>
  <dt id="lid"><a class="permalink" href="#lid"><code class="Li">lid</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports an ACPI laptop lid switch, which
      typically puts a system to sleep.</dd>
  <dt id="mwait"><a class="permalink" href="#mwait"><code class="Li">mwait</code></a></dt>
  <dd>(<var class="Vt">feature</var>) Do not ask firmware for available
      x86-vendor specific methods to enter <code class="Li">Cx</code> sleep
      states. Only query and use the generic I/O-based entrance method. The knob
      is provided to work around inconsistencies in the tables filled by
      firmware.</dd>
  <dt id="quirks"><a class="permalink" href="#quirks"><code class="Li">quirks</code></a></dt>
  <dd>(<var class="Vt">feature</var>) Do not honor quirks. Quirks automatically
      disable ACPI functionality based on the XSDT table's OEM vendor name and
      revision date.</dd>
  <dt id="pci"><a class="permalink" href="#pci"><code class="Li">pci</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports Host to PCI bridges.</dd>
  <dt id="pci_link"><a class="permalink" href="#pci_link"><code class="Li">pci_link</code></a></dt>
  <dd>(<var class="Vt">feature</var>) Performs PCI interrupt routing.</dd>
  <dt id="sysresource"><a class="permalink" href="#sysresource"><code class="Li">sysresource</code></a></dt>
  <dd>(<var class="Vt">device</var>) Pseudo-devices containing resources which
      ACPI claims.</dd>
  <dt id="thermal"><a class="permalink" href="#thermal"><code class="Li">thermal</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports system cooling and heat
      management.</dd>
  <dt id="timer"><a class="permalink" href="#timer"><code class="Li">timer</code></a></dt>
  <dd>(<var class="Vt">device</var>) Implements a timecounter using the ACPI
      fixed-frequency timer.</dd>
  <dt id="video"><a class="permalink" href="#video"><code class="Li">video</code></a></dt>
  <dd>(<var class="Vt">device</var>) Supports <a class="Xr">acpi_video(4)</a>
      which may conflict with <a class="Xr">agp(4)</a> device.</dd>
</dl>
<p class="Pp">It is also possible to avoid portions of the ACPI namespace which
    may be causing problems, by listing the full path of the root of the region
    to be avoided in the kernel environment variable
    <var class="Va">debug.acpi.avoid</var>. The object and all of its children
    will be ignored during the bus/children scan of the namespace. The ACPI CA
    code will still know about the avoided region.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DEBUGGING_OUTPUT"><a class="permalink" href="#DEBUGGING_OUTPUT">DEBUGGING
  OUTPUT</a></h1>
<p class="Pp">To enable debugging output, <code class="Nm">acpi</code> must be
    compiled with <code class="Cd">options ACPI_DEBUG</code>. Debugging output
    is separated between layers and levels, where a layer is a component of the
    ACPI subsystem, and a level is a particular kind of debugging output.</p>
<p class="Pp">Both layers and levels are specified as a whitespace-separated
    list of tokens, with layers listed in <var class="Va">debug.acpi.layer</var>
    and levels in <var class="Va">debug.acpi.level</var>.</p>
<p class="Pp">The first set of layers is for ACPI-CA components, and the second
    is for <span class="Ux">FreeBSD</span> drivers. The ACPI-CA layer
    descriptions include the prefix for the files they refer to. The supported
    layers are:</p>
<p class="Pp"></p>
<dl class="Bl-tag Bl-compact">
  <dt id="ACPI_UTILITIES"><a class="permalink" href="#ACPI_UTILITIES"><code class="Li">ACPI_UTILITIES</code></a></dt>
  <dd>Utility (&quot;ut&quot;) functions</dd>
  <dt id="ACPI_HARDWARE"><a class="permalink" href="#ACPI_HARDWARE"><code class="Li">ACPI_HARDWARE</code></a></dt>
  <dd>Hardware access (&quot;hw&quot;)</dd>
  <dt id="ACPI_EVENTS"><a class="permalink" href="#ACPI_EVENTS"><code class="Li">ACPI_EVENTS</code></a></dt>
  <dd>Event and GPE (&quot;ev&quot;)</dd>
  <dt id="ACPI_TABLES"><a class="permalink" href="#ACPI_TABLES"><code class="Li">ACPI_TABLES</code></a></dt>
  <dd>Table access (&quot;tb&quot;)</dd>
  <dt id="ACPI_NAMESPACE"><a class="permalink" href="#ACPI_NAMESPACE"><code class="Li">ACPI_NAMESPACE</code></a></dt>
  <dd>Namespace evaluation (&quot;ns&quot;)</dd>
  <dt id="ACPI_PARSER"><a class="permalink" href="#ACPI_PARSER"><code class="Li">ACPI_PARSER</code></a></dt>
  <dd>AML parser (&quot;ps&quot;)</dd>
  <dt id="ACPI_DISPATCHER"><a class="permalink" href="#ACPI_DISPATCHER"><code class="Li">ACPI_DISPATCHER</code></a></dt>
  <dd>Internal representation of interpreter state (&quot;ds&quot;)</dd>
  <dt id="ACPI_EXECUTER"><a class="permalink" href="#ACPI_EXECUTER"><code class="Li">ACPI_EXECUTER</code></a></dt>
  <dd>Execute AML methods (&quot;ex&quot;)</dd>
  <dt id="ACPI_RESOURCES"><a class="permalink" href="#ACPI_RESOURCES"><code class="Li">ACPI_RESOURCES</code></a></dt>
  <dd>Resource parsing (&quot;rs&quot;)</dd>
  <dt id="ACPI_CA_DEBUGGER"><a class="permalink" href="#ACPI_CA_DEBUGGER"><code class="Li">ACPI_CA_DEBUGGER</code></a></dt>
  <dd>Debugger implementation (&quot;db&quot;, &quot;dm&quot;)</dd>
  <dt id="ACPI_OS_SERVICES"><a class="permalink" href="#ACPI_OS_SERVICES"><code class="Li">ACPI_OS_SERVICES</code></a></dt>
  <dd>Usermode support routines (&quot;os&quot;)</dd>
  <dt id="ACPI_CA_DISASSEMBLER"><a class="permalink" href="#ACPI_CA_DISASSEMBLER"><code class="Li">ACPI_CA_DISASSEMBLER</code></a></dt>
  <dd>Disassembler implementation (unused)</dd>
  <dt id="ACPI_ALL_COMPONENTS"><a class="permalink" href="#ACPI_ALL_COMPONENTS"><code class="Li">ACPI_ALL_COMPONENTS</code></a></dt>
  <dd>All the above ACPI-CA components</dd>
  <dt id="ACPI_AC_ADAPTER"><a class="permalink" href="#ACPI_AC_ADAPTER"><code class="Li">ACPI_AC_ADAPTER</code></a></dt>
  <dd>AC adapter driver</dd>
  <dt id="ACPI_BATTERY"><a class="permalink" href="#ACPI_BATTERY"><code class="Li">ACPI_BATTERY</code></a></dt>
  <dd>Control-method battery driver</dd>
  <dt id="ACPI_BUS"><a class="permalink" href="#ACPI_BUS"><code class="Li">ACPI_BUS</code></a></dt>
  <dd>ACPI, ISA, and PCI bus drivers</dd>
  <dt id="ACPI_BUTTON"><a class="permalink" href="#ACPI_BUTTON"><code class="Li">ACPI_BUTTON</code></a></dt>
  <dd>Power and sleep button driver</dd>
  <dt id="ACPI_EC"><a class="permalink" href="#ACPI_EC"><code class="Li">ACPI_EC</code></a></dt>
  <dd>Embedded controller driver</dd>
  <dt id="ACPI_FAN"><a class="permalink" href="#ACPI_FAN"><code class="Li">ACPI_FAN</code></a></dt>
  <dd>Fan driver</dd>
  <dt id="ACPI_OEM"><a class="permalink" href="#ACPI_OEM"><code class="Li">ACPI_OEM</code></a></dt>
  <dd>Platform-specific driver for hotkeys, LED, etc.</dd>
  <dt id="ACPI_POWERRES"><a class="permalink" href="#ACPI_POWERRES"><code class="Li">ACPI_POWERRES</code></a></dt>
  <dd>Power resource driver</dd>
  <dt id="ACPI_PROCESSOR"><a class="permalink" href="#ACPI_PROCESSOR"><code class="Li">ACPI_PROCESSOR</code></a></dt>
  <dd>CPU driver</dd>
  <dt id="ACPI_SPMC"><a class="permalink" href="#ACPI_SPMC"><code class="Li">ACPI_SPMC</code></a></dt>
  <dd>System power management controller driver</dd>
  <dt id="ACPI_THERMAL"><a class="permalink" href="#ACPI_THERMAL"><code class="Li">ACPI_THERMAL</code></a></dt>
  <dd>Thermal zone driver</dd>
  <dt id="ACPI_TIMER"><a class="permalink" href="#ACPI_TIMER"><code class="Li">ACPI_TIMER</code></a></dt>
  <dd>Timer driver</dd>
  <dt id="ACPI_ALL_DRIVERS"><a class="permalink" href="#ACPI_ALL_DRIVERS"><code class="Li">ACPI_ALL_DRIVERS</code></a></dt>
  <dd>All the above <span class="Ux">FreeBSD</span> ACPI drivers</dd>
</dl>
<p class="Pp">The supported levels are:</p>
<p class="Pp"></p>
<dl class="Bl-tag Bl-compact">
  <dt id="ACPI_LV_INIT"><a class="permalink" href="#ACPI_LV_INIT"><code class="Li">ACPI_LV_INIT</code></a></dt>
  <dd>Initialization progress</dd>
  <dt id="ACPI_LV_DEBUG_OBJECT"><a class="permalink" href="#ACPI_LV_DEBUG_OBJECT"><code class="Li">ACPI_LV_DEBUG_OBJECT</code></a></dt>
  <dd>Stores to objects</dd>
  <dt id="ACPI_LV_INFO"><a class="permalink" href="#ACPI_LV_INFO"><code class="Li">ACPI_LV_INFO</code></a></dt>
  <dd>General information and progress</dd>
  <dt id="ACPI_LV_REPAIR"><a class="permalink" href="#ACPI_LV_REPAIR"><code class="Li">ACPI_LV_REPAIR</code></a></dt>
  <dd>Repair a common problem with predefined methods</dd>
  <dt id="ACPI_LV_ALL_EXCEPTIONS"><a class="permalink" href="#ACPI_LV_ALL_EXCEPTIONS"><code class="Li">ACPI_LV_ALL_EXCEPTIONS</code></a></dt>
  <dd>All the previous levels</dd>
  <dt id="ACPI_LV_PARSE"><a class="permalink" href="#ACPI_LV_PARSE"><code class="Li">ACPI_LV_PARSE</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_DISPATCH"><a class="permalink" href="#ACPI_LV_DISPATCH"><code class="Li">ACPI_LV_DISPATCH</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_EXEC"><a class="permalink" href="#ACPI_LV_EXEC"><code class="Li">ACPI_LV_EXEC</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_NAMES"><a class="permalink" href="#ACPI_LV_NAMES"><code class="Li">ACPI_LV_NAMES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_OPREGION"><a class="permalink" href="#ACPI_LV_OPREGION"><code class="Li">ACPI_LV_OPREGION</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_BFIELD"><a class="permalink" href="#ACPI_LV_BFIELD"><code class="Li">ACPI_LV_BFIELD</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_TABLES"><a class="permalink" href="#ACPI_LV_TABLES"><code class="Li">ACPI_LV_TABLES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VALUES"><a class="permalink" href="#ACPI_LV_VALUES"><code class="Li">ACPI_LV_VALUES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_OBJECTS"><a class="permalink" href="#ACPI_LV_OBJECTS"><code class="Li">ACPI_LV_OBJECTS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_RESOURCES"><a class="permalink" href="#ACPI_LV_RESOURCES"><code class="Li">ACPI_LV_RESOURCES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_USER_REQUESTS"><a class="permalink" href="#ACPI_LV_USER_REQUESTS"><code class="Li">ACPI_LV_USER_REQUESTS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_PACKAGE"><a class="permalink" href="#ACPI_LV_PACKAGE"><code class="Li">ACPI_LV_PACKAGE</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VERBOSITY1"><a class="permalink" href="#ACPI_LV_VERBOSITY1"><code class="Li">ACPI_LV_VERBOSITY1</code></a></dt>
  <dd>All the previous levels</dd>
  <dt id="ACPI_LV_ALLOCATIONS"><a class="permalink" href="#ACPI_LV_ALLOCATIONS"><code class="Li">ACPI_LV_ALLOCATIONS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_FUNCTIONS"><a class="permalink" href="#ACPI_LV_FUNCTIONS"><code class="Li">ACPI_LV_FUNCTIONS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_OPTIMIZATIONS"><a class="permalink" href="#ACPI_LV_OPTIMIZATIONS"><code class="Li">ACPI_LV_OPTIMIZATIONS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VERBOSITY2"><a class="permalink" href="#ACPI_LV_VERBOSITY2"><code class="Li">ACPI_LV_VERBOSITY2</code></a></dt>
  <dd>All the previous levels</dd>
  <dt id="ACPI_LV_ALL"><a class="permalink" href="#ACPI_LV_ALL"><code class="Li">ACPI_LV_ALL</code></a></dt>
  <dd>Synonym for &quot;<code class="Li">ACPI_LV_VERBOSITY2</code>&quot;</dd>
  <dt id="ACPI_LV_MUTEX"><a class="permalink" href="#ACPI_LV_MUTEX"><code class="Li">ACPI_LV_MUTEX</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_THREADS"><a class="permalink" href="#ACPI_LV_THREADS"><code class="Li">ACPI_LV_THREADS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_IO"><a class="permalink" href="#ACPI_LV_IO"><code class="Li">ACPI_LV_IO</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_INTERRUPTS"><a class="permalink" href="#ACPI_LV_INTERRUPTS"><code class="Li">ACPI_LV_INTERRUPTS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VERBOSITY3"><a class="permalink" href="#ACPI_LV_VERBOSITY3"><code class="Li">ACPI_LV_VERBOSITY3</code></a></dt>
  <dd>All the previous levels</dd>
  <dt id="ACPI_LV_AML_DISASSEMBLE"><a class="permalink" href="#ACPI_LV_AML_DISASSEMBLE"><code class="Li">ACPI_LV_AML_DISASSEMBLE</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VERBOSE_INFO"><a class="permalink" href="#ACPI_LV_VERBOSE_INFO"><code class="Li">ACPI_LV_VERBOSE_INFO</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_FULL_TABLES"><a class="permalink" href="#ACPI_LV_FULL_TABLES"><code class="Li">ACPI_LV_FULL_TABLES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_EVENTS"><a class="permalink" href="#ACPI_LV_EVENTS"><code class="Li">ACPI_LV_EVENTS</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_VERBOSE"><a class="permalink" href="#ACPI_LV_VERBOSE"><code class="Li">ACPI_LV_VERBOSE</code></a></dt>
  <dd>All levels after
    &quot;<code class="Li">ACPI_LV_VERBOSITY3</code>&quot;</dd>
  <dt id="ACPI_LV_INIT_NAMES"><a class="permalink" href="#ACPI_LV_INIT_NAMES"><code class="Li">ACPI_LV_INIT_NAMES</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
  <dt id="ACPI_LV_LOAD"><a class="permalink" href="#ACPI_LV_LOAD"><code class="Li">ACPI_LV_LOAD</code></a></dt>
  <dd style="width: auto;">&#x00A0;</dd>
</dl>
<p class="Pp">Selection of the appropriate layer and level values is important
    to avoid massive amounts of debugging output. For example, the following
    configuration is a good way to gather initial information. It enables debug
    output for both ACPI-CA and the <code class="Nm">acpi</code> driver,
    printing basic information about errors, warnings, and progress.</p>
<div class="Bd Pp Bd-indent Li">
<pre>debug.acpi.layer=&quot;ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS&quot;
debug.acpi.level=&quot;ACPI_LV_ALL_EXCEPTIONS&quot;</pre>
</div>
<p class="Pp">Debugging output by the ACPI CA subsystem is prefixed with the
    module name in lowercase, followed by a source line number. Output from the
    <span class="Ux">FreeBSD</span>-local code follows the same format, but the
    module name is uppercased.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="OVERRIDING_YOUR_BIOS_BYTECODE"><a class="permalink" href="#OVERRIDING_YOUR_BIOS_BYTECODE">OVERRIDING
  YOUR BIOS BYTECODE</a></h1>
<p class="Pp">ACPI interprets bytecode named AML (ACPI Machine Language)
    provided by the BIOS vendor as a memory image at boot time. Sometimes, the
    AML code contains a bug that does not appear when parsed by the Microsoft
    implementation. <span class="Ux">FreeBSD</span> provides a way to override
    it with your own AML code to work around or debug such problems. Note that
    all AML in your DSDT and any SSDT tables is overridden.</p>
<p class="Pp">In order to load your AML code, you must edit
    <span class="Pa">/boot/loader.conf</span> and include the following
  lines.</p>
<div class="Bd Pp Bd-indent Li">
<pre>acpi_dsdt_load=&quot;YES&quot;
acpi_dsdt_name=&quot;/boot/acpi_dsdt.aml&quot; # You may change this name.</pre>
</div>
<p class="Pp">In order to prepare your AML code, you will need the
    <a class="Xr">acpidump(8)</a> and <a class="Xr">iasl(8)</a> utilities and
    some ACPI knowledge.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="COMPATIBILITY"><a class="permalink" href="#COMPATIBILITY">COMPATIBILITY</a></h1>
<p class="Pp">ACPI is only found and supported on i386/ia32 and amd64.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
  ALSO</a></h1>
<p class="Pp"><a class="Xr">kenv(1)</a>, <a class="Xr">acpi_thermal(4)</a>,
    <a class="Xr">device.hints(5)</a>, <a class="Xr">loader.conf(5)</a>,
    <a class="Xr">acpiconf(8)</a>, <a class="Xr">acpidump(8)</a>,
    <a class="Xr">config(8)</a>, <a class="Xr">iasl(8)</a></p>
<p class="Pp"><cite class="Rs"><span class="RsA">Compaq Computer
    Corporation</span>, <span class="RsA">Intel Corporation</span>,
    <span class="RsA">Microsoft Corporation</span>, <span class="RsA">Phoenix
    Technologies Ltd.</span>, and <span class="RsA">Toshiba Corporation</span>,
    <span class="RsT">Advanced Configuration and Power Interface
    Specification</span>,
    <a class="RsU" href="http://acpi.info/spec.htm">http://acpi.info/spec.htm</a>,
    <span class="RsD">August 25, 2003</span>.</cite></p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">The ACPI CA subsystem is developed and maintained by Intel
    Architecture Labs.</p>
<p class="Pp">The following people made notable contributions to the ACPI
    subsystem in <span class="Ux">FreeBSD</span>: <span class="An">Michael
    Smith</span>, <span class="An">Takanori Watanabe</span>
    &lt;<a class="Mt" href="mailto:takawata@jp.FreeBSD.org">takawata@jp.FreeBSD.org</a>&gt;,
    <span class="An">Mitsuru IWASAKI</span>
    &lt;<a class="Mt" href="mailto:iwasaki@jp.FreeBSD.org">iwasaki@jp.FreeBSD.org</a>&gt;,
    <span class="An">Munehiro Matsuda</span>, <span class="An">Nate
    Lawson</span>, the ACPI-jp mailing list at
    &lt;<a class="Mt" href="mailto:acpi-jp@jp.FreeBSD.org">acpi-jp@jp.FreeBSD.org</a>&gt;,
    and many other contributors.</p>
<p class="Pp">This manual page was written by <span class="An">Michael
    Smith</span>
    &lt;<a class="Mt" href="mailto:msmith@FreeBSD.org">msmith@FreeBSD.org</a>&gt;.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1>
<p class="Pp">Many BIOS versions have serious bugs that may cause system
    instability, break suspend/resume, or prevent devices from operating
    properly due to IRQ routing problems. Upgrade your BIOS to the latest
    version available from the vendor before deciding it is a problem with
    <code class="Nm">acpi</code>.</p>
</section>
</div>
<table class="foot">
  <tr>
    <td class="foot-date">March 21, 2026</td>
    <td class="foot-os">FreeBSD 15.0</td>
  </tr>
</table>