linux/Documentation/acpi/debug.txt
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   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
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