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