Merge tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
[sfrench/cifs-2.6.git] / Documentation / firmware-guide / acpi / debug.rst
1 .. SPDX-License-Identifier: GPL-2.0
2
3 =================
4 ACPI Debug Output
5 =================
6
7 The ACPI CA, the Linux ACPI core, and some ACPI drivers can generate debug
8 output.  This document describes how to use this facility.
9
10 Compile-time configuration
11 ==========================
12
13 ACPI debug output is globally enabled by CONFIG_ACPI_DEBUG.  If this config
14 option is turned off, the debug messages are not even built into the
15 kernel.
16
17 Boot- and run-time configuration
18 ================================
19
20 When CONFIG_ACPI_DEBUG=y, you can select the component and level of messages
21 you're interested in.  At boot-time, use the acpi.debug_layer and
22 acpi.debug_level kernel command line options.  After boot, you can use the
23 debug_layer and debug_level files in /sys/module/acpi/parameters/ to control
24 the debug messages.
25
26 debug_layer (component)
27 =======================
28
29 The "debug_layer" is a mask that selects components of interest, e.g., a
30 specific driver or part of the ACPI interpreter.  To build the debug_layer
31 bitmask, look for the "#define _COMPONENT" in an ACPI source file.
32
33 You can set the debug_layer mask at boot-time using the acpi.debug_layer
34 command line argument, and you can change it after boot by writing values
35 to /sys/module/acpi/parameters/debug_layer.
36
37 The possible components are defined in include/acpi/acoutput.h and
38 include/acpi/acpi_drivers.h.  Reading /sys/module/acpi/parameters/debug_layer
39 shows the supported mask values, currently these::
40
41     ACPI_UTILITIES                  0x00000001
42     ACPI_HARDWARE                   0x00000002
43     ACPI_EVENTS                     0x00000004
44     ACPI_TABLES                     0x00000008
45     ACPI_NAMESPACE                  0x00000010
46     ACPI_PARSER                     0x00000020
47     ACPI_DISPATCHER                 0x00000040
48     ACPI_EXECUTER                   0x00000080
49     ACPI_RESOURCES                  0x00000100
50     ACPI_CA_DEBUGGER                0x00000200
51     ACPI_OS_SERVICES                0x00000400
52     ACPI_CA_DISASSEMBLER            0x00000800
53     ACPI_COMPILER                   0x00001000
54     ACPI_TOOLS                      0x00002000
55     ACPI_BUS_COMPONENT              0x00010000
56     ACPI_AC_COMPONENT               0x00020000
57     ACPI_BATTERY_COMPONENT          0x00040000
58     ACPI_BUTTON_COMPONENT           0x00080000
59     ACPI_SBS_COMPONENT              0x00100000
60     ACPI_FAN_COMPONENT              0x00200000
61     ACPI_PCI_COMPONENT              0x00400000
62     ACPI_POWER_COMPONENT            0x00800000
63     ACPI_CONTAINER_COMPONENT        0x01000000
64     ACPI_SYSTEM_COMPONENT           0x02000000
65     ACPI_THERMAL_COMPONENT          0x04000000
66     ACPI_MEMORY_DEVICE_COMPONENT    0x08000000
67     ACPI_VIDEO_COMPONENT            0x10000000
68     ACPI_PROCESSOR_COMPONENT        0x20000000
69
70 debug_level
71 ===========
72
73 The "debug_level" is a mask that selects different types of messages, e.g.,
74 those related to initialization, method execution, informational messages, etc.
75 To build debug_level, look at the level specified in an ACPI_DEBUG_PRINT()
76 statement.
77
78 The ACPI interpreter uses several different levels, but the Linux
79 ACPI core and ACPI drivers generally only use ACPI_LV_INFO.
80
81 You can set the debug_level mask at boot-time using the acpi.debug_level
82 command line argument, and you can change it after boot by writing values
83 to /sys/module/acpi/parameters/debug_level.
84
85 The possible levels are defined in include/acpi/acoutput.h.  Reading
86 /sys/module/acpi/parameters/debug_level shows the supported mask values,
87 currently these::
88
89     ACPI_LV_INIT                    0x00000001
90     ACPI_LV_DEBUG_OBJECT            0x00000002
91     ACPI_LV_INFO                    0x00000004
92     ACPI_LV_INIT_NAMES              0x00000020
93     ACPI_LV_PARSE                   0x00000040
94     ACPI_LV_LOAD                    0x00000080
95     ACPI_LV_DISPATCH                0x00000100
96     ACPI_LV_EXEC                    0x00000200
97     ACPI_LV_NAMES                   0x00000400
98     ACPI_LV_OPREGION                0x00000800
99     ACPI_LV_BFIELD                  0x00001000
100     ACPI_LV_TABLES                  0x00002000
101     ACPI_LV_VALUES                  0x00004000
102     ACPI_LV_OBJECTS                 0x00008000
103     ACPI_LV_RESOURCES               0x00010000
104     ACPI_LV_USER_REQUESTS           0x00020000
105     ACPI_LV_PACKAGE                 0x00040000
106     ACPI_LV_ALLOCATIONS             0x00100000
107     ACPI_LV_FUNCTIONS               0x00200000
108     ACPI_LV_OPTIMIZATIONS           0x00400000
109     ACPI_LV_MUTEX                   0x01000000
110     ACPI_LV_THREADS                 0x02000000
111     ACPI_LV_IO                      0x04000000
112     ACPI_LV_INTERRUPTS              0x08000000
113     ACPI_LV_AML_DISASSEMBLE         0x10000000
114     ACPI_LV_VERBOSE_INFO            0x20000000
115     ACPI_LV_FULL_TABLES             0x40000000
116     ACPI_LV_EVENTS                  0x80000000
117
118 Examples
119 ========
120
121 For example, drivers/acpi/bus.c contains this::
122
123     #define _COMPONENT              ACPI_BUS_COMPONENT
124     ...
125     ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device insertion detected\n"));
126
127 To turn on this message, set the ACPI_BUS_COMPONENT bit in acpi.debug_layer
128 and the ACPI_LV_INFO bit in acpi.debug_level.  (The ACPI_DEBUG_PRINT
129 statement uses ACPI_DB_INFO, which is macro based on the ACPI_LV_INFO
130 definition.)
131
132 Enable all AML "Debug" output (stores to the Debug object while interpreting
133 AML) during boot::
134
135     acpi.debug_layer=0xffffffff acpi.debug_level=0x2
136
137 Enable PCI and PCI interrupt routing debug messages::
138
139     acpi.debug_layer=0x400000 acpi.debug_level=0x4
140
141 Enable all ACPI hardware-related messages::
142
143     acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
144
145 Enable all ACPI_DB_INFO messages after boot::
146
147     # echo 0x4 > /sys/module/acpi/parameters/debug_level
148
149 Show all valid component values::
150
151     # cat /sys/module/acpi/parameters/debug_layer