- ACPI Debug Output
+.. SPDX-License-Identifier: GPL-2.0
+=================
+ACPI Debug Output
+=================
The ACPI CA, the Linux ACPI core, and some ACPI drivers can generate debug
output. This document describes how to use this facility.
Compile-time configuration
---------------------------
+==========================
ACPI debug output is globally enabled by CONFIG_ACPI_DEBUG. If this config
option is turned off, the debug messages are not even built into the
kernel.
Boot- and run-time configuration
---------------------------------
+================================
When CONFIG_ACPI_DEBUG=y, you can select the component and level of messages
you're interested in. At boot-time, use the acpi.debug_layer and
the debug messages.
debug_layer (component)
------------------------
+=======================
The "debug_layer" is a mask that selects components of interest, e.g., a
specific driver or part of the ACPI interpreter. To build the debug_layer
The possible components are defined in include/acpi/acoutput.h and
include/acpi/acpi_drivers.h. Reading /sys/module/acpi/parameters/debug_layer
-shows the supported mask values, currently these:
+shows the supported mask values, currently these::
ACPI_UTILITIES 0x00000001
ACPI_HARDWARE 0x00000002
ACPI_PROCESSOR_COMPONENT 0x20000000
debug_level
------------
+===========
The "debug_level" is a mask that selects different types of messages, e.g.,
those related to initialization, method execution, informational messages, etc.
The possible levels are defined in include/acpi/acoutput.h. Reading
/sys/module/acpi/parameters/debug_level shows the supported mask values,
-currently these:
+currently these::
ACPI_LV_INIT 0x00000001
ACPI_LV_DEBUG_OBJECT 0x00000002
ACPI_LV_EVENTS 0x80000000
Examples
---------
+========
-For example, drivers/acpi/bus.c contains this:
+For example, drivers/acpi/bus.c contains this::
#define _COMPONENT ACPI_BUS_COMPONENT
...
definition.)
Enable all AML "Debug" output (stores to the Debug object while interpreting
-AML) during boot:
+AML) during boot::
acpi.debug_layer=0xffffffff acpi.debug_level=0x2
-Enable PCI and PCI interrupt routing debug messages:
+Enable PCI and PCI interrupt routing debug messages::
acpi.debug_layer=0x400000 acpi.debug_level=0x4
-Enable all ACPI hardware-related messages:
+Enable all ACPI hardware-related messages::
acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
-Enable all ACPI_DB_INFO messages after boot:
+Enable all ACPI_DB_INFO messages after boot::
# echo 0x4 > /sys/module/acpi/parameters/debug_level
-Show all valid component values:
+Show all valid component values::
# cat /sys/module/acpi/parameters/debug_layer