[ISSUE] trace_id of ETM will be invalid when there are more than 48 CPUs on chip

[liuqi (BA)]

Hi Mike,

On 2022/5/16 20:23, Mike Leach wrote:
> Hi
> 
> On Mon, 16 May 2022 at 04:51, liuqi (BA) <liuqi115 at huawei.com> wrote:
>>
>> Hi all,
>>
>> My colleague Junhao He noticed this issue when tracing CPU48 on
>> Kunpeng920 platform, log as follows:
>>
>> [root at localhost ~]# perf record -e cs_etm/@sink_smb1/ -C 48 -o perf.data
>> taskset -c 48 uname -a
>> [root at localhost ~]# perf report -D --stdio -i perf.data > perf_48.log
>> 0x270 [0xc8]: failed to process type: 70 [Invalid argument]
>> Error:
>> failed to process sample
>> [root at localhost ~]# perf -v
>> perf version 5.17.rc4.gdeea22e4af29
>> [root at localhost ~]# ldd /usr/bin/perf | grep opencsd
>>           libopencsd_c_api.so.1 => /root/lib/libopencsd_c_api.so.1
>>           libopencsd.so.1 => /root/lib/libopencsd.so.1
>>
>> As (CORESIGHT_ETM_PMU_SEED + (cpu * 2)) is used in
>> coresight_get_trace_id() to cacualate trace_id, if there are more than
>> 48 CPUs on chip, we will have some ETM device which trace id is
>> invalid(trace_id = 0 or trace_id > 0x6F). In this situation, we cannot
>> parse trace data using perf tool.
>>
>> Perhaps we should make trace_id in the range of 1 to 0x6F in
>> coresight_get_trace_id()? But there also might be parsing problem if
>> duplicate trace ID is used during collection.
>>
>> Any response will be highly appreciated.
>>
>> Thanks,
>> Qi
> 
> Addressed by patchset here:
> 
> [PATCH 00/10] coresight: Add new API to allocate trace source ID values
> https://lists.linaro.org/archives/list/coresight@lists.linaro.org/thread/BJEO7KMX723YZWVTPWAY7F3GWSVTO644/
> 
> Version 2 of this patchset is to be published in due course.
> 

got it, I'll have a look at this series, thanks!

Regards,
Qi

> Regards
> 
> Mike
>