1			ACPI Debug Output
2
3
4The ACPI CA, the Linux ACPI core, and some ACPI drivers can generate debug
5output.  This document describes how to use this facility.
6
7Compile-time configuration
8--------------------------
9
10ACPI debug output is globally enabled by CONFIG_ACPI_DEBUG.  If this config
11option is turned off, the debug messages are not even built into the
12kernel.
13
14Boot- and run-time configuration
15--------------------------------
16
17When CONFIG_ACPI_DEBUG=y, you can select the component and level of messages
18you're interested in.  At boot-time, use the acpi.debug_layer and
19acpi.debug_level kernel command line options.  After boot, you can use the
20debug_layer and debug_level files in /sys/module/acpi/parameters/ to control
21the debug messages.
22
23debug_layer (component)
24-----------------------
25
26The "debug_layer" is a mask that selects components of interest, e.g., a
27specific driver or part of the ACPI interpreter.  To build the debug_layer
28bitmask, look for the "#define _COMPONENT" in an ACPI source file.
29
30You can set the debug_layer mask at boot-time using the acpi.debug_layer
31command line argument, and you can change it after boot by writing values
32to /sys/module/acpi/parameters/debug_layer.
33
34The possible components are defined in include/acpi/acoutput.h and
35include/acpi/acpi_drivers.h.  Reading /sys/module/acpi/parameters/debug_layer
36shows the supported mask values, currently these:
37
38    ACPI_UTILITIES                  0x00000001
39    ACPI_HARDWARE                   0x00000002
40    ACPI_EVENTS                     0x00000004
41    ACPI_TABLES                     0x00000008
42    ACPI_NAMESPACE                  0x00000010
43    ACPI_PARSER                     0x00000020
44    ACPI_DISPATCHER                 0x00000040
45    ACPI_EXECUTER                   0x00000080
46    ACPI_RESOURCES                  0x00000100
47    ACPI_CA_DEBUGGER                0x00000200
48    ACPI_OS_SERVICES                0x00000400
49    ACPI_CA_DISASSEMBLER            0x00000800
50    ACPI_COMPILER                   0x00001000
51    ACPI_TOOLS                      0x00002000
52    ACPI_BUS_COMPONENT              0x00010000
53    ACPI_AC_COMPONENT               0x00020000
54    ACPI_BATTERY_COMPONENT          0x00040000
55    ACPI_BUTTON_COMPONENT           0x00080000
56    ACPI_SBS_COMPONENT              0x00100000
57    ACPI_FAN_COMPONENT              0x00200000
58    ACPI_PCI_COMPONENT              0x00400000
59    ACPI_POWER_COMPONENT            0x00800000
60    ACPI_CONTAINER_COMPONENT        0x01000000
61    ACPI_SYSTEM_COMPONENT           0x02000000
62    ACPI_THERMAL_COMPONENT          0x04000000
63    ACPI_MEMORY_DEVICE_COMPONENT    0x08000000
64    ACPI_VIDEO_COMPONENT            0x10000000
65    ACPI_PROCESSOR_COMPONENT        0x20000000
66
67debug_level
68-----------
69
70The "debug_level" is a mask that selects different types of messages, e.g.,
71those related to initialization, method execution, informational messages, etc.
72To build debug_level, look at the level specified in an ACPI_DEBUG_PRINT()
73statement.
74
75The ACPI interpreter uses several different levels, but the Linux
76ACPI core and ACPI drivers generally only use ACPI_LV_INFO.
77
78You can set the debug_level mask at boot-time using the acpi.debug_level
79command line argument, and you can change it after boot by writing values
80to /sys/module/acpi/parameters/debug_level.
81
82The possible levels are defined in include/acpi/acoutput.h.  Reading
83/sys/module/acpi/parameters/debug_level shows the supported mask values,
84currently these:
85
86    ACPI_LV_INIT                    0x00000001
87    ACPI_LV_DEBUG_OBJECT            0x00000002
88    ACPI_LV_INFO                    0x00000004
89    ACPI_LV_INIT_NAMES              0x00000020
90    ACPI_LV_PARSE                   0x00000040
91    ACPI_LV_LOAD                    0x00000080
92    ACPI_LV_DISPATCH                0x00000100
93    ACPI_LV_EXEC                    0x00000200
94    ACPI_LV_NAMES                   0x00000400
95    ACPI_LV_OPREGION                0x00000800
96    ACPI_LV_BFIELD                  0x00001000
97    ACPI_LV_TABLES                  0x00002000
98    ACPI_LV_VALUES                  0x00004000
99    ACPI_LV_OBJECTS                 0x00008000
100    ACPI_LV_RESOURCES               0x00010000
101    ACPI_LV_USER_REQUESTS           0x00020000
102    ACPI_LV_PACKAGE                 0x00040000
103    ACPI_LV_ALLOCATIONS             0x00100000
104    ACPI_LV_FUNCTIONS               0x00200000
105    ACPI_LV_OPTIMIZATIONS           0x00400000
106    ACPI_LV_MUTEX                   0x01000000
107    ACPI_LV_THREADS                 0x02000000
108    ACPI_LV_IO                      0x04000000
109    ACPI_LV_INTERRUPTS              0x08000000
110    ACPI_LV_AML_DISASSEMBLE         0x10000000
111    ACPI_LV_VERBOSE_INFO            0x20000000
112    ACPI_LV_FULL_TABLES             0x40000000
113    ACPI_LV_EVENTS                  0x80000000
114
115Examples
116--------
117
118For example, drivers/acpi/bus.c contains this:
119
120    #define _COMPONENT              ACPI_BUS_COMPONENT
121    ...
122    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device insertion detected\n"));
123
124To turn on this message, set the ACPI_BUS_COMPONENT bit in acpi.debug_layer
125and the ACPI_LV_INFO bit in acpi.debug_level.  (The ACPI_DEBUG_PRINT
126statement uses ACPI_DB_INFO, which is macro based on the ACPI_LV_INFO
127definition.)
128
129Enable all AML "Debug" output (stores to the Debug object while interpreting
130AML) during boot:
131
132    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
133
134Enable PCI and PCI interrupt routing debug messages:
135
136    acpi.debug_layer=0x400000 acpi.debug_level=0x4
137
138Enable all ACPI hardware-related messages:
139
140    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
141
142Enable all ACPI_DB_INFO messages after boot:
143
144    # echo 0x4 > /sys/module/acpi/parameters/debug_level
145
146Show all valid component values:
147
148    # cat /sys/module/acpi/parameters/debug_layer
149