On Thu, Nov 08, 2018 at 04:51:52PM +0800, leo....@linaro.org wrote: > Hi Jiri, > > On Wed, Nov 07, 2018 at 03:10:06PM +0100, Jiri Olsa wrote: > > On Fri, Nov 02, 2018 at 10:55:16AM +0800, leo....@linaro.org wrote: > > > Hi all, > > > > > > Now I found that if use the command 'perf script' for Arm CoreSight trace > > > data, it fails to parse kernel symbols if we don't specify kernel vmlinux > > > file. So when we don't specify kernel symbol files then perf tool will > > > roll back to use /proc/kallsyms for kernel symbols parsing, as result it > > > will > > > run into below flow: > > > > yep, AFAIK if there's no vmlinux found we fallback to /proc/kallsyms > > > > > > > > thread__find_addr_map(thread, cpumode, MAP__FUNCTION, address, &al); > > > map__load(al.map); > > > dso__data_read_offset(al.map->dso, machine, offset, buffer, size); > > > `-> data_read_offset() > > > > so what is the actual error you see in the perf script? > > unresolved samples? could you please describe your config > > and workload? > > So at my side the error is the CoreSight trace decoder fails to > generate samples if the sample has kernel address, thus the decoder > doesn't generate any kernel sample if use kallsyms as dso. > > For more detailed info is: the CoreSight decoder needs firstly to get > dso related info by calling dso__data_read_offset() [1], if we use > kallsyms then this function always returns failure then this leads the > docoder to discard all kernel samples.
I haven't checked on this code for some time but AFAICS before you call dso__data_read_offset you need to check dso->data.status != DSO_DATA_STATUS_ERROR map__load call ahead should take care on setting this and find the source of the data check the intel_pt code (intel_pt_walk_next_insn) or for example grab_bb in perf script I guess you need to have either vmlinux or kcore in place to get some data out of it jirka
