1.. SPDX-License-Identifier: GPL-2.0 2 3================= 4ACPI Debug Output 5================= 6 7The ACPI CA, the Linux ACPI core, and some ACPI drivers can generate debug 8output. This document describes how to use this facility. 9 10Compile-time configuration 11========================== 12 13ACPI debug output is globally enabled by CONFIG_ACPI_DEBUG. If this config 14option is turned off, the debug messages are not even built into the 15kernel. 16 17Boot- and run-time configuration 18================================ 19 20When CONFIG_ACPI_DEBUG=y, you can select the component and level of messages 21you're interested in. At boot-time, use the acpi.debug_layer and 22acpi.debug_level kernel command line options. After boot, you can use the 23debug_layer and debug_level files in /sys/module/acpi/parameters/ to control 24the debug messages. 25 26debug_layer (component) 27======================= 28 29The "debug_layer" is a mask that selects components of interest, e.g., a 30specific driver or part of the ACPI interpreter. To build the debug_layer 31bitmask, look for the "#define _COMPONENT" in an ACPI source file. 32 33You can set the debug_layer mask at boot-time using the acpi.debug_layer 34command line argument, and you can change it after boot by writing values 35to /sys/module/acpi/parameters/debug_layer. 36 37The possible components are defined in include/acpi/acoutput.h and 38include/acpi/acpi_drivers.h. Reading /sys/module/acpi/parameters/debug_layer 39shows 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 70debug_level 71=========== 72 73The "debug_level" is a mask that selects different types of messages, e.g., 74those related to initialization, method execution, informational messages, etc. 75To build debug_level, look at the level specified in an ACPI_DEBUG_PRINT() 76statement. 77 78The ACPI interpreter uses several different levels, but the Linux 79ACPI core and ACPI drivers generally only use ACPI_LV_INFO. 80 81You can set the debug_level mask at boot-time using the acpi.debug_level 82command line argument, and you can change it after boot by writing values 83to /sys/module/acpi/parameters/debug_level. 84 85The possible levels are defined in include/acpi/acoutput.h. Reading 86/sys/module/acpi/parameters/debug_level shows the supported mask values, 87currently 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 118Examples 119======== 120 121For 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 127To turn on this message, set the ACPI_BUS_COMPONENT bit in acpi.debug_layer 128and the ACPI_LV_INFO bit in acpi.debug_level. (The ACPI_DEBUG_PRINT 129statement uses ACPI_DB_INFO, which is macro based on the ACPI_LV_INFO 130definition.) 131 132Enable all AML "Debug" output (stores to the Debug object while interpreting 133AML) during boot:: 134 135 acpi.debug_layer=0xffffffff acpi.debug_level=0x2 136 137Enable PCI and PCI interrupt routing debug messages:: 138 139 acpi.debug_layer=0x400000 acpi.debug_level=0x4 140 141Enable all ACPI hardware-related messages:: 142 143 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff 144 145Enable all ACPI_DB_INFO messages after boot:: 146 147 # echo 0x4 > /sys/module/acpi/parameters/debug_level 148 149Show all valid component values:: 150 151 # cat /sys/module/acpi/parameters/debug_layer 152