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

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

Documentation/trace/stm.txt

+12 −1
Original line number Diff line number Diff line
@@ -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



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

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 
beginning of this text on how to do that). When initialized, it will

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

[2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html