Hi Mathieu,
I will like to ask how I might be able to configure the options in trcconfig driver file, found in /sys/bus/coresight/devices/*.etm/mgmt/ .
For example, the trcidr0 denotes that tssize = 64bits (which indicates that timestamps are supported), retstack, cc, bb are also supported.
However, my trcconfig file shows that none of the options are activated.
In the *.etm driver files, it has the following files in it that I thought might have been linked to trcconfig, or at least be related to activating some of the options that are currently activated: 1. bb_ctrl (obviously bb) 2. cntr_ctrl 3. cyc_threshold (cc?) 4. event_ts (ts)
I am hoping that help in activating these options can be provided.
On another note, I will also like to ask if there might be example files that I may refer to to using sequencer/resource/events.
In the *.etm file, there are seq_event,seq_idx,seq_reset_event,seq_state/res_ctrl, res_idx/event,event_instren,event_ts,event_vinst in the respective order (seq/res/events). I will like to understand how I might use these features to improve my tracing results. As well as understanding the various values I could apply to the mode file.
As quoted in sysfs-bus-coresight-devices-etm4x, What: /sys/bus/coresight/devices/<memory_map>.etm/mode Date: April 2015 KernelVersion: 4.01 Contact: Mathieu Poirier mathieu.poirier@linaro.org Description: (RW) Controls various modes supported by this ETM, for example P0 instruction tracing, branch broadcast, cycle counting and context ID tracing.
However it does not explain how that file can control various modes. I have tried toying with this files and it went from useful tracing results to just kernel instruction tracing results. After applying 0x0 to the mode again (which was the default value when i start up my device), I am unable to re-obtain useful trace results and had to resort to re-power my device.
Lastly, I understand that nr_ss_cmp meant that my etm can only have 1 single-shot comparator during a trace (correct me if I am wrong). This explains why when I applied 0x3 to addr_idx and set addr_start value, I am unable to set a value for addr_stop. On the other hand,i have 0x4 nr_addr_cmp. However, I do not understand how I might be able to use the other 2 addr comparator (i.e. when addr_idx = 0, I am able to set addr_start and addr_stop, which took up 2 addr_cmp. How then, might I be able to use the other 2 addr_cmp?)
My apologies for many amateurish questions. I have been looking at the etm documentation (IHI0064F), particularly on comparators, bb, ts, events, resources but unfortunately unable to connect the dots on how I might be able to use them with the coresight drivers.
Yours Sincerely, Jeremy Ng