>
>-----Original Message-----
>From: Steven Rostedt <rostedt@xxxxxxxxxxx>
>Sent: Friday, January 14, 2022 3:10 AM
>To: Chen, Hongzhan <hongzhan.chen@xxxxxxxxx>
>Cc: linux-trace-devel@xxxxxxxxxxxxxxx" <linux-trace-devel@xxxxxxxxxxxxxxx>, Kiszka; Jan <jan.kiszka@xxxxxxxxxxx>
>Subject: Re: [Questions][trace-cmd/libtraceevent] how to correctly parse info out from specifial format of event?
>
>On Thu, 13 Jan 2022 08:20:16 +0000
>"Chen, Hongzhan" <hongzhan.chen@xxxxxxxxx> wrote:
>
>> When I tried to analysis trace log that captured from xenomai system with kernelshark, I found
>> that it report "FAILED TO PARSE" for some events. These events have format like [1].
>> In trace, these events would be printed like [2].
>> At first, I was trying to develop new libtraceevent plugin to parse this event correctly.
>> When I refer to code plugins/plugin_mac80211.c of libtraceevent to parse field param_ex
>> out for this __data_loc type of data, I always get value 0x380018 and It is supposed to trace_seq_printf
>> 0x38 size of string got from offset 0x18 of tep_record->data but it fail. After debug, I found
>> that the data start from offset 0x18 is not what we expect and first few bytes of data is like [3].
>>
>
>Could show me a full binary dump of the data for the record in your plugin?
>
>That is, something like this:
>
>tep_register_event_handler(tep, -1, "cobalt_posix",
> "cobalt_pthread_create",
> dump_event, NULL);
>
>
>static int dump_event(struct trace_seq *s,
> struct tep_record *record,
> struct tep_event *event, void *context)
>{
> unsigned char c;
> int i;
>
> for (i = 0; i < record->size; i++) {
> c = *(unsigned char *)(record->data + i);
> trace_seq_printf(s, "%02x", c);
> if (i < record->size - 1) {
> if ((i & 0x7) == 7)
> trace_seq_puts(s, " ");
> else
> trace_seq_putc(s, ' ');
> }
> }
> return 0;
>}
>
Following is two dumps, please check:
smokey-447 [000] 320.193156: cobalt_pthread_create: 74 02 00 00 bf 01 00 00 40 37 4b aa ab 7f 00 00 00 00 00 00 18 00 38 00 00 00 00 00 fe 7f 00 00 60 c3 24 90 ff ff ff ff 5c 81 21 90 ff ff ff ff d8 bd 8c 80 90 c1 ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
smokey-449 [000] 320.196623: cobalt_pthread_create: 74 02 00 00 c1 01 00 00 00 e7 6e a9 ab 7f 00 00 01 00 00 00 18 00 38 00 01 00 00 00 30 00 00 00 20 7c 82 77 fe 7f 00 00 60 7b 82 77 fe 7f 00 00 00 2b 89 18 55 a6 fa ba 40 37 4b aa ab 7f 00 00 3e 3d e2 00 7f 55 00 00 d0 7b 82 77 fe 7f 00 00
Regards
Hongzhan Chen
>
>Thanks,
>
>-- Steve
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