diff options
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/coresight.txt | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index 0a5c3290e732..a33c88cd5d1d 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -190,8 +190,8 @@ expected to be accessed and controlled using those entries. Last but not least, "struct module *owner" is expected to be set to reflect the information carried in "THIS_MODULE". -How to use ----------- +How to use the tracer modules +----------------------------- Before trace collection can start, a coresight sink needs to be identify. There is no limit on the amount of sinks (nor sources) that can be enabled at @@ -297,3 +297,36 @@ Info Tracing enabled Instruction 13570831 0x8026B584 E28DD00C false ADD sp,sp,#0xc Instruction 0 0x8026B588 E8BD8000 true LDM sp!,{pc} Timestamp Timestamp: 17107041535 + +How to use the STM module +------------------------- + +Using the System Trace Macrocell module is the same as the tracers - the only +difference is that clients are driving the trace capture rather +than the program flow through the code. + +As with any other CoreSight component, specifics about the STM tracer can be +found in sysfs with more information on each entry being found in [1]: + +root@genericarmv8:~# ls /sys/bus/coresight/devices/20100000.stm +enable_source hwevent_select port_enable subsystem uevent +hwevent_enable mgmt port_select traceid +root@genericarmv8:~# + +Like any other source a sink needs to be identified and the STM enabled before +being used: + +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20010000.etf/enable_sink +root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20100000.stm/enable_source + +From there user space applications can request and use channels using the devfs +interface provided for that purpose by the generic STM API: + +root@genericarmv8:~# ls -l /dev/20100000.stm +crw------- 1 root root 10, 61 Jan 3 18:11 /dev/20100000.stm +root@genericarmv8:~# + +Details on how to use the generic STM API can be found here [2]. + +[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm +[2]. Documentation/trace/stm.txt |