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1.. SPDX-License-Identifier: GPL-2.02 3====================4ACPI CA Debug Output5====================6 7The ACPI CA can generate debug output. This document describes how to use this8facility.9 10Compile-time configuration11==========================12 13The ACPI CA debug output is globally enabled by CONFIG_ACPI_DEBUG. If this14config option is not set, the debug messages are not even built into the kernel.15 16Boot- and run-time configuration17================================18 19When CONFIG_ACPI_DEBUG=y, you can select the component and level of messages20you're interested in. At boot-time, use the acpi.debug_layer and21acpi.debug_level kernel command line options. After boot, you can use the22debug_layer and debug_level files in /sys/module/acpi/parameters/ to control23the debug messages.24 25debug_layer (component)26=======================27 28The "debug_layer" is a mask that selects components of interest, e.g., a29specific part of the ACPI interpreter. To build the debug_layer bitmask, look30for the "#define _COMPONENT" in an ACPI source file.31 32You can set the debug_layer mask at boot-time using the acpi.debug_layer33command line argument, and you can change it after boot by writing values34to /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 0x0000000141 ACPI_HARDWARE 0x0000000242 ACPI_EVENTS 0x0000000443 ACPI_TABLES 0x0000000844 ACPI_NAMESPACE 0x0000001045 ACPI_PARSER 0x0000002046 ACPI_DISPATCHER 0x0000004047 ACPI_EXECUTER 0x0000008048 ACPI_RESOURCES 0x0000010049 ACPI_CA_DEBUGGER 0x0000020050 ACPI_OS_SERVICES 0x0000040051 ACPI_CA_DISASSEMBLER 0x0000080052 ACPI_COMPILER 0x0000100053 ACPI_TOOLS 0x0000200054 55debug_level56===========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 Linux64ACPI 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_level67command line argument, and you can change it after boot by writing values68to /sys/module/acpi/parameters/debug_level.69 70The possible levels are defined in include/acpi/acoutput.h. Reading71/sys/module/acpi/parameters/debug_level shows the supported mask values,72currently these::73 74 ACPI_LV_INIT 0x0000000175 ACPI_LV_DEBUG_OBJECT 0x0000000276 ACPI_LV_INFO 0x0000000477 ACPI_LV_INIT_NAMES 0x0000002078 ACPI_LV_PARSE 0x0000004079 ACPI_LV_LOAD 0x0000008080 ACPI_LV_DISPATCH 0x0000010081 ACPI_LV_EXEC 0x0000020082 ACPI_LV_NAMES 0x0000040083 ACPI_LV_OPREGION 0x0000080084 ACPI_LV_BFIELD 0x0000100085 ACPI_LV_TABLES 0x0000200086 ACPI_LV_VALUES 0x0000400087 ACPI_LV_OBJECTS 0x0000800088 ACPI_LV_RESOURCES 0x0001000089 ACPI_LV_USER_REQUESTS 0x0002000090 ACPI_LV_PACKAGE 0x0004000091 ACPI_LV_ALLOCATIONS 0x0010000092 ACPI_LV_FUNCTIONS 0x0020000093 ACPI_LV_OPTIMIZATIONS 0x0040000094 ACPI_LV_MUTEX 0x0100000095 ACPI_LV_THREADS 0x0200000096 ACPI_LV_IO 0x0400000097 ACPI_LV_INTERRUPTS 0x0800000098 ACPI_LV_AML_DISASSEMBLE 0x1000000099 ACPI_LV_VERBOSE_INFO 0x20000000100 ACPI_LV_FULL_TABLES 0x40000000101 ACPI_LV_EVENTS 0x80000000102 103Examples104========105 106For example, drivers/acpi/acpica/evxfevnt.c contains this::107 108 #define _COMPONENT ACPI_EVENTS109 ...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_layer113and the ACPI_LV_INIT bit in acpi.debug_level. (The ACPI_DEBUG_PRINT114statement uses ACPI_DB_INIT, which is a macro based on the ACPI_LV_INIT115definition.)116 117Enable all AML "Debug" output (stores to the Debug object while interpreting118AML) during boot::119 120 acpi.debug_layer=0xffffffff acpi.debug_level=0x2121 122Enable all ACPI hardware-related messages::123 124 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff125 126Enable all ACPI_DB_INFO messages after boot::127 128 # echo 0x4 > /sys/module/acpi/parameters/debug_level129 130Show all valid component values::131 132 # cat /sys/module/acpi/parameters/debug_layer133