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ACPI(4) NetBSD Kernel Interfaces Manual ACPI(4)
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acpi -- Advanced Configuration and Power Interface
acpi0 at mainbus0
NetBSD provides machine-independent bus support for Advanced Configura-
tion and Power Interface (ACPI) devices and includes several ACPI device
The NetBSD implementation of ACPI integrates Intel's ACPI Component
Architecture (ACPI-CA) for the OS-independent part. The ACPI-CA provides
OS-neutral ACPI functionalities such as ACPI BIOS table support, an ACPI
event framework and an ACPI Machine Language (AML) interpreter.
ACPI_DEBUG Enable various debug facilities.
ACPIVERBOSE Enable verbose debug messages.
ACPI_ACTIVATE_DEV Determine if the ACPI driver should
attempt to activate inactive devices.
The default is off.
ACPI_DSDT_OVERRIDE Force a given Differentiated System
Description Table (DSDT) instead of the
version supplied by the BIOS. Use
ACPI_DSDT_FILE to specify a DSDT.
ACPI_DSDT_FILE="filename" If ACPI_DSDT_FILE is not specified,
default to ``dsdt.hex'' in the build
ACPI_BLACKLIST_YEAR=2000 Do not use ACPI with any BIOS made on or
before the specified year.
ACPI__DIS_IS_BROKEN Do not call the ACPI "_DIS" method to
disable interrupt links. This may be
required on specific ``nForce4'' chipset
systems, which hard hang when this method
is called instead of having it fail
The following sysctl(8) variables are provided by the acpi driver:
The address of the ACPI root pointer in system memory.
The system sleep state.
A list of system sleep states that the machine supports.
The possible values are:
S0 fully running
S1 power on suspend (CPU and hard disks are off)
S2 similar to S3, usually not implemented
S4 suspend-to-disk (not supported on NetBSD)
S5 power off
A boolean variable that controls whether the PC speaker
beeps upon resume. Only available on i386 and amd64 archi-
Defines the handling of the graphics card on i386 and amd64
architectures. The supported values are:
0 No attempt to reset the VGA controller will be made.
1 Call the VGA BIOS when still in real mode. This can
result in direct reboots. In that case, use `2' or
vbetool post from the pkgsrc/sysutils/vbetool pack-
2 Call the VGA BIOS using the in-kernel x86 emulator.
If the system has problems in resuming from the S3 state,
experimenting with different values may provide a solution.
The number of dispatched General Purpose Events (GPEs).
The number of System Control Interrupts (SCIs). See
acpiec(4) for a brief description of both GPEs and SCIs.
The number of ``fixed events''.
The number of AML methods executed by the interpreter.
This read-only node describes the ACPI power state of
devices. The values range from D0 (``on'') to D3
This node represents devices that can wake the system from
the S3 or S4 sleep state. By default, acpibut(4),
acpilid(4), and pckbd(4) are allowed to wake the system,
provided that the devices are present and the firmware sup-
ports wake-up capabilities for the devices.
NetBSD ACPI supports several machine-dependent and machine-independent
devices, some specific to ACPI and some configured via it.
acpiacad(4) ACPI AC adapters.
acpibat(4) ACPI batteries.
acpibut(4) ACPI power and sleep buttons.
acpicpu(4) ACPI processors.
acpidalb(4) ACPI direction application launch buttons.
acpiec(4) ACPI embedded controllers.
acpiecdt(4) ACPI Embedded Controller Boot Resource Table (ECDT).
acpifan(4) ACPI fans.
acpilid(4) ACPI lid switches.
acpipmtr(4) ACPI power meters.
acpismbus(4) ACPI SMBus via control method interface (CMI).
acpitz(4) ACPI thermal zones.
acpivga(4) ACPI display adapter and output devices.
acpiwmi(4) ACPI support for Windows Management Instrumentation.
acpiwdrt(4) ACPI watchdogs.
aibs(4) ASUSTeK voltage, temperature and fan sensors.
asus(4) ASUS laptop hotkeys.
attimer(4) AT Timer.
com(4) NS8250-, NS16450-, and NS16550-based serial ports.
fdc(4) Floppy disk controllers.
fujbp(4) Fujitsu brightness and pointer.
fujhk(4) Fujitsu hotkeys.
hpacel(4) HP 3D DriveGuard accelerometer.
hpet(4) High Precision Event Timer (HPET).
hpqlb(4) HP Quick Launch Buttons.
joy(4) Joystick/Game port interface.
lpt(4) Standard ISA parallel port interface.
mpu(4) Roland MPU-401 (compatible) MIDI UART.
pcppi(4) AT-style speaker sound.
sdhc(4) SD Host Controller.
thinkpad(4) IBM/Lenovo ThinkPad laptop device driver.
ug(4) Abit uGuru Hardware monitor.
vald(4) Toshiba Libretto device.
valz(4) Toshiba Dynabook device.
wb(4) Winbond W83L518D Integrated Media Reader.
wss(4) Windows Sound System-compatible sound cards
ym(4) Yamaha OPL3-SA2 and OPL3-SA3 audio device driver.
pckbc(4) PC keyboard controllers.
sony(4) Sony Miscellaneous Controller
spic(4) Sony programmable I/O controller.
Although the situation has become better over the years, ACPI is typi-
cally prone to various errors, ranging from blatant flaws in the firmware
to bugs in the implementation. Before anything else, it is a good prac-
tice to upgrade the BIOS to the latest version available from the vendor.
To ease the task of diagnosing and fixing different problems, the ACPICA
reference implementation provides a rich facility of different debugging
methods. In NetBSD these are generally only available if the kernel has
been compiled with the ACPI_DEBUG option.
The ACPIVERBOSE compile time option enables some verbose debug messages
printed during the system startup. In a MODULAR (see options(4)) system,
the information can be printed also at runtime, regardless of the pres-
ence of ACPIVERBOSE. To print the messages, modload(8) the acpiverbose
module using the option -b dump=true.
ACPI interprets bytecode known as ACPI Machine Language (AML), provided
by the BIOS as a memory image during the system bootstrap. Most of the
AML relevant to acpi is implemented in the so-called Differentiated Sys-
tem Descriptor Table (DSDT). NetBSD provides support for overriding the
default DSDT supplied by the BIOS.
The following steps can be used to override the DSDT:
1. Dump the raw DSDT with acpidump(8).
2. Disassemble the table with iasl(8).
3. Modify the disassembled table.
4. Compile the table with iasl(8) using the option -tc.
5. Either copy the (*.hex) file to
or use the option
in the kernel configuration file.
6. Define ACPI_DSDT_OVERRIDE in the kernel configuration file and
The ACPICA interpreter provides its own debugger for low-level debugging.
It can be used to display internal data structures and namespace objects,
and to debug the execution of control methods. Single step and break-
point functionality are available. In NetBSD this is integrated to the
in-kernel ddb(4). In order to enter the ACPICA debugger from ddb(4), use
the command call with the argument acpi_osd_debugger.
NetBSD provides three sysctl(8) variables that control the debug output
at runtime. The hw.acpi.debug.layer variable limits the output to a spe-
cific ACPI layer and the hw.acpi.debug.level variable controls the debug
level. Both sysctl(8) variables are string literals. The third variable
is hw.acpi.debug.object. This is a boolean that controls whether debug
messages internal to the AML are enabled.
For the first two variables, the possible values are:
ACPI_TABLES ACPI_LV_ALL_EXCEPTIONS *
ACPI_ALL_COMPONENTS * ACPI_LV_RESOURCES
ACPI_ACAD_COMPONENT ACPI_LV_VERBOSITY1 *
ACPI_RESOURCE_COMPONENT ACPI_LV_VERBOSITY2 *
ACPI_ALL_DRIVERS * ACPI_LV_MUTEX
* This is a compound ACPI_LV_VERBOSITY3 *
all previous elements. ACPI_LV_AML_DISASSEMBLE
In addition, there is ACPI_DEBUG_DEFAULT that is used by ACPICA as the
default debug level. It includes ACPI_LV_INIT and ACPI_LV_DEBUG_OBJECT.
The debug layer can be divided into two groups: the first one is specific
to the ACPICA interpreter and the second one contains the internal ACPI
components of NetBSD. The constant ACPI_ALL_DRIVERS includes all NetBSD
The ACPICA interpreter uses several debug levels internally, but the
NetBSD specific parts are typically limited to ACPI_LV_DEBUG_OBJECT and
ACPI_LV_INFO. The debug output can be stopped by setting
hw.acpi.debug.level to ACPI_DEBUG_NONE.
As an example, a driver may have defined the component it belongs to and
the name of the module:
#define _COMPONENT ACPI_BUS_COMPONENT
The driver may also utilize the debug facility:
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Failed to evaluate _STA\n"));
With these options the debug message from the ACPI_DEBUG_PRINT macro is
only visible when hw.acpi.debug.layer is either ACPI_BUS_COMPONENT or a
compound constant including it, and hw.acpi.debug.level is ACPI_LV_INFO
or some constant that includes it. Finally, it can be noted that the
ACPI implementation uses the prefix ACPI_DB, whereas the debug level
sysctl(8) variable is always specified with the prefix ACPI_LV.
Another example can be mentioned for the use of hw.acpi.debug.object.
The following could appear in an ASL code:
Method(_Q19, 0, NotSerialized)
Store("_Q19 invoked", Debug)
When hw.acpi.debug.object is set to 1, the message stored to the debug
object is printed every time the method is called by the interpreter.
ioapic(4), acpidump(8), amldb(8), iasl(8)
Hewlett-Packard Corporation, Intel Corporation, Microsoft Corporation,
Phoenix Technologies Ltd., and Toshiba Corporation, Advanced
Configuration and Power Interface Specification, Revision 4.0,
http://www.acpi.info/spec.htm, June 16, 2009.
Intel Corporation, ACPI Component Architecture, Programmer Reference, OS-
Independent Subsystem, Debugger, and Utilities, Revision 1.27,
http://www.acpica.org/download/acpica-reference.pdf, January 20, 2010.
Len Brown, ACPI in Linux - Myths vs. Reality,
65-74, June 27-30, 2007, Proceedings of the Linux Symposium.
Joerg Sonnenberger and Jared D. McNeill, Sleeping Beauty - NetBSD on
Modern Laptops, http://2008.asiabsdcon.org/papers/P9A-paper.pdf, 127-134,
February 3, 2008, Proceedings of AsiaBSDCon 2008.
Takanori Watanabe, "ACPI Implementation on FreeBSD", Proceedings of the
FREENIX Track: 2002 USENIX Annual Technical Conference, USENIX
121-131, June 10-15, 2002.
The acpi driver appeared in NetBSD 1.6.
Authors of the acpi subsystem include Charles M. Hannum, Frank van der
Linden, Jared D. McNeill, Jason R. Thorpe, Joerg Sonnenberger, and Jukka
Ruohonen, among others.
Most of the ACPI power management functionalities are not implemented.
The ACPI__DIS_IS_BROKEN option should not be necessary.
NetBSD 9.3 March 4, 2018 NetBSD 9.3