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Diffstat (limited to 'kernel/Documentation/acpi/method-tracing.txt')
| -rw-r--r-- | kernel/Documentation/acpi/method-tracing.txt | 204 |
1 files changed, 185 insertions, 19 deletions
diff --git a/kernel/Documentation/acpi/method-tracing.txt b/kernel/Documentation/acpi/method-tracing.txt index f6efb1ea5..c2505eefc 100644 --- a/kernel/Documentation/acpi/method-tracing.txt +++ b/kernel/Documentation/acpi/method-tracing.txt @@ -1,26 +1,192 @@ -/sys/module/acpi/parameters/: +ACPICA Trace Facility -trace_method_name - The AML method name that the user wants to trace +Copyright (C) 2015, Intel Corporation +Author: Lv Zheng <lv.zheng@intel.com> -trace_debug_layer - The temporary debug_layer used when tracing the method. - Using 0xffffffff by default if it is 0. -trace_debug_level - The temporary debug_level used when tracing the method. - Using 0x00ffffff by default if it is 0. +Abstract: -trace_state - The status of the tracing feature. +This document describes the functions and the interfaces of the method +tracing facility. + +1. Functionalities and usage examples: + + ACPICA provides method tracing capability. And two functions are + currently implemented using this capability. + + A. Log reducer + ACPICA subsystem provides debugging outputs when CONFIG_ACPI_DEBUG is + enabled. The debugging messages which are deployed via + ACPI_DEBUG_PRINT() macro can be reduced at 2 levels - per-component + level (known as debug layer, configured via + /sys/module/acpi/parameters/debug_layer) and per-type level (known as + debug level, configured via /sys/module/acpi/parameters/debug_level). + + But when the particular layer/level is applied to the control method + evaluations, the quantity of the debugging outputs may still be too + large to be put into the kernel log buffer. The idea thus is worked out + to only enable the particular debug layer/level (normally more detailed) + logs when the control method evaluation is started, and disable the + detailed logging when the control method evaluation is stopped. + + The following command examples illustrate the usage of the "log reducer" + functionality: + a. Filter out the debug layer/level matched logs when control methods + are being evaluated: + # cd /sys/module/acpi/parameters + # echo "0xXXXXXXXX" > trace_debug_layer + # echo "0xYYYYYYYY" > trace_debug_level + # echo "enable" > trace_state + b. Filter out the debug layer/level matched logs when the specified + control method is being evaluated: + # cd /sys/module/acpi/parameters + # echo "0xXXXXXXXX" > trace_debug_layer + # echo "0xYYYYYYYY" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "method" > /sys/module/acpi/parameters/trace_state + c. Filter out the debug layer/level matched logs when the specified + control method is being evaluated for the first time: + # cd /sys/module/acpi/parameters + # echo "0xXXXXXXXX" > trace_debug_layer + # echo "0xYYYYYYYY" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "method-once" > /sys/module/acpi/parameters/trace_state + Where: + 0xXXXXXXXX/0xYYYYYYYY: Refer to Documentation/acpi/debug.txt for + possible debug layer/level masking values. + \PPPP.AAAA.TTTT.HHHH: Full path of a control method that can be found + in the ACPI namespace. It needn't be an entry + of a control method evaluation. + + B. AML tracer + + There are special log entries added by the method tracing facility at + the "trace points" the AML interpreter starts/stops to execute a control + method, or an AML opcode. Note that the format of the log entries are + subject to change: + [ 0.186427] exdebug-0398 ex_trace_point : Method Begin [0xf58394d8:\_SB.PCI0.LPCB.ECOK] execution. + [ 0.186630] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905c88:If] execution. + [ 0.186820] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905cc0:LEqual] execution. + [ 0.187010] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905a20:-NamePath-] execution. + [ 0.187214] exdebug-0398 ex_trace_point : Opcode End [0xf5905a20:-NamePath-] execution. + [ 0.187407] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905f60:One] execution. + [ 0.187594] exdebug-0398 ex_trace_point : Opcode End [0xf5905f60:One] execution. + [ 0.187789] exdebug-0398 ex_trace_point : Opcode End [0xf5905cc0:LEqual] execution. + [ 0.187980] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905cc0:Return] execution. + [ 0.188146] exdebug-0398 ex_trace_point : Opcode Begin [0xf5905f60:One] execution. + [ 0.188334] exdebug-0398 ex_trace_point : Opcode End [0xf5905f60:One] execution. + [ 0.188524] exdebug-0398 ex_trace_point : Opcode End [0xf5905cc0:Return] execution. + [ 0.188712] exdebug-0398 ex_trace_point : Opcode End [0xf5905c88:If] execution. + [ 0.188903] exdebug-0398 ex_trace_point : Method End [0xf58394d8:\_SB.PCI0.LPCB.ECOK] execution. - "enabled" means this feature is enabled - and the AML method is traced every time it's executed. + Developers can utilize these special log entries to track the AML + interpretion, thus can aid issue debugging and performance tuning. Note + that, as the "AML tracer" logs are implemented via ACPI_DEBUG_PRINT() + macro, CONFIG_ACPI_DEBUG is also required to be enabled for enabling + "AML tracer" logs. - "1" means this feature is enabled and the AML method - will only be traced during the next execution. + The following command examples illustrate the usage of the "AML tracer" + functionality: + a. Filter out the method start/stop "AML tracer" logs when control + methods are being evaluated: + # cd /sys/module/acpi/parameters + # echo "0x80" > trace_debug_layer + # echo "0x10" > trace_debug_level + # echo "enable" > trace_state + b. Filter out the method start/stop "AML tracer" when the specified + control method is being evaluated: + # cd /sys/module/acpi/parameters + # echo "0x80" > trace_debug_layer + # echo "0x10" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "method" > trace_state + c. Filter out the method start/stop "AML tracer" logs when the specified + control method is being evaluated for the first time: + # cd /sys/module/acpi/parameters + # echo "0x80" > trace_debug_layer + # echo "0x10" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "method-once" > trace_state + d. Filter out the method/opcode start/stop "AML tracer" when the + specified control method is being evaluated: + # cd /sys/module/acpi/parameters + # echo "0x80" > trace_debug_layer + # echo "0x10" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "opcode" > trace_state + e. Filter out the method/opcode start/stop "AML tracer" when the + specified control method is being evaluated for the first time: + # cd /sys/module/acpi/parameters + # echo "0x80" > trace_debug_layer + # echo "0x10" > trace_debug_level + # echo "\PPPP.AAAA.TTTT.HHHH" > trace_method_name + # echo "opcode-opcode" > trace_state - "disabled" means this feature is disabled. - Users can enable/disable this debug tracing feature by - "echo string > /sys/module/acpi/parameters/trace_state". - "string" should be one of "enable", "disable" and "1". + Note that all above method tracing facility related module parameters can + be used as the boot parameters, for example: + acpi.trace_debug_layer=0x80 acpi.trace_debug_level=0x10 \ + acpi.trace_method_name=\_SB.LID0._LID acpi.trace_state=opcode-once + +2. Interface descriptions: + + All method tracing functions can be configured via ACPI module + parameters that are accessible at /sys/module/acpi/parameters/: + + trace_method_name + The full path of the AML method that the user wants to trace. + Note that the full path shouldn't contain the trailing "_"s in its + name segments but may contain "\" to form an absolute path. + + trace_debug_layer + The temporary debug_layer used when the tracing feature is enabled. + Using ACPI_EXECUTER (0x80) by default, which is the debug_layer + used to match all "AML tracer" logs. + + trace_debug_level + The temporary debug_level used when the tracing feature is enabled. + Using ACPI_LV_TRACE_POINT (0x10) by default, which is the + debug_level used to match all "AML tracer" logs. + + trace_state + The status of the tracing feature. + Users can enable/disable this debug tracing feature by executing + the following command: + # echo string > /sys/module/acpi/parameters/trace_state + Where "string" should be one of the followings: + "disable" + Disable the method tracing feature. + "enable" + Enable the method tracing feature. + ACPICA debugging messages matching + "trace_debug_layer/trace_debug_level" during any method + execution will be logged. + "method" + Enable the method tracing feature. + ACPICA debugging messages matching + "trace_debug_layer/trace_debug_level" during method execution + of "trace_method_name" will be logged. + "method-once" + Enable the method tracing feature. + ACPICA debugging messages matching + "trace_debug_layer/trace_debug_level" during method execution + of "trace_method_name" will be logged only once. + "opcode" + Enable the method tracing feature. + ACPICA debugging messages matching + "trace_debug_layer/trace_debug_level" during method/opcode + execution of "trace_method_name" will be logged. + "opcode-once" + Enable the method tracing feature. + ACPICA debugging messages matching + "trace_debug_layer/trace_debug_level" during method/opcode + execution of "trace_method_name" will be logged only once. + Note that, the difference between the "enable" and other feature + enabling options are: + 1. When "enable" is specified, since + "trace_debug_layer/trace_debug_level" shall apply to all control + method evaluations, after configuring "trace_state" to "enable", + "trace_method_name" will be reset to NULL. + 2. When "method/opcode" is specified, if + "trace_method_name" is NULL when "trace_state" is configured to + these options, the "trace_debug_layer/trace_debug_level" will + apply to all control method evaluations. |