Commit 39fccd2f authored by Chunyan Zhang's avatar Chunyan Zhang Committed by Alexander Shishkin

stm class: Document the stm_ftrace

This patch adds a description to the stm_ftrace device source, an
interface for collecting Ftrace's function trace information via
STM devices.
Signed-off-by: default avatarChunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
parent 71c488f3
...@@ -83,7 +83,7 @@ by writing the name of the desired stm device there, for example: ...@@ -83,7 +83,7 @@ by writing the name of the desired stm device there, for example:
$ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link $ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link
For examples on how to use stm_source interface in the kernel, refer For examples on how to use stm_source interface in the kernel, refer
to stm_console or stm_heartbeat drivers. to stm_console, stm_heartbeat or stm_ftrace drivers.
Each stm_source device will need to assume a master and a range of Each stm_source device will need to assume a master and a range of
channels, depending on how many channels it requires. These are channels, depending on how many channels it requires. These are
...@@ -107,5 +107,16 @@ console in the STP stream, create a "console" policy entry (see the ...@@ -107,5 +107,16 @@ console in the STP stream, create a "console" policy entry (see the
beginning of this text on how to do that). When initialized, it will beginning of this text on how to do that). When initialized, it will
consume one channel. consume one channel.
stm_ftrace
==========
This is another "stm_source" device, once the stm_ftrace has been
linked with an stm device, and if "function" tracer is enabled,
function address and parent function address which Ftrace subsystem
would store into ring buffer will be exported via the stm device at
the same time.
Currently only Ftrace "function" tracer is supported.
[1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf [1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf
[2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html [2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html
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