mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
cb4ff766c4
This patch updates method tracing documentation. Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
192 lines
9 KiB
Text
192 lines
9 KiB
Text
ACPICA Trace Facility
|
|
|
|
Copyright (C) 2015, Intel Corporation
|
|
Author: Lv Zheng <lv.zheng@intel.com>
|
|
|
|
|
|
Abstract:
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
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
|
|
|
|
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.
|