>-----Original Message-----
>From: Steven Rostedt <rostedt@xxxxxxxxxxx>
>Sent: Friday, January 14, 2022 10:07 AM
>To: Chen, Hongzhan <hongzhan.chen@xxxxxxxxx>
>Cc: linux-trace-devel@xxxxxxxxxxxxxxx>, Kiszka <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 Fri, 14 Jan 2022 01:37:08 +0000
>"Chen, Hongzhan" <hongzhan.chen@xxxxxxxxx> wrote:
>
>From your other email:
>
>> root@ecs-xenomai-isar:~# cat /sys/kernel/debug/tracing/events/cobalt_posix/cobalt_pthread_create/format
>> name: cobalt_pthread_create
>> ID: 628
>> format:
>> field:unsigned short common_type; offset:0; size:2; signed:0;
>> field:unsigned char common_flags; offset:2; size:1; signed:0;
>> field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
>> field:int common_pid; offset:4; size:4; signed:1;
>>
>> field:unsigned long pth; offset:8; size:8; signed:0;
>> field:int policy; offset:16; size:4; signed:1;
>> field:__data_loc char[] param_ex; offset:20; size:4; signed:1;
>>
>> print fmt: "pth=%p policy=%s param=' %s '", (void *)REC->pth, __print_symbolic(REC->policy,
>> {0, "normal"}, {1, "fifo"}, {2, "rr"}, {11, "tp"}, {12, "quota"}, {10, "sporadic"}, {42, "cobalt"},
>> {43, "weak"}), cobalt_trace_parse_sched_params(p, REC->policy, (struct sched_param_ex *)(__get_dynamic_array(param_ex)))
>>
>> [2]:
>> smokey-752 [000] d.~2 7970.727466: cobalt_pthread_getschedparam: pth=000000009bbc7fe0 policy=fifo param={ priority=50 }
>> smokey-762 [000] .... 7970.727492: cobalt_pthread_create: pth=00000000983468a5 policy=quota param={ priority=1, group=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
>
>common_type: 0x0274 = 628 (matches the ID)
>common_flags: 00
>common_preempt_count: 00
>common_pid: 0x000001bf : 447
>
>pth: 0x00007fabaa4b3f40 (whatever that is)
>policy: 0x00000000
>param_ex: 0x00180038 (offset = 0x38 (56) len=0x18 (24)
Thanks for your quick reply. 😊
On my X86 platform , it is printed as 0x380018(offset should be 0x18 len = 0x38). It should point to the end of field param_ex (field:__data_loc char[] param_ex; offset:20; size:4; signed:1) where store its data per my understanding. Please correct me if I am wrong.
>
>Hmm, the offset points to that set of zeros at the end.
>
>How was this event created?
The event definition please refer to https://gitlab.com/Xenomai/xenomai-hacker-space/-/blob/master/kernel/cobalt/trace/cobalt-posix.h
Regards
Hongzhan Chen
>
>> 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
>
>Although the above has content for that:
>
> "40 37 4b aa ab 7f 00 00 3e 3d e2 00 7f 55 00 00 d0 7b 82 77 fe 7f 00 00"
>
>-- Steve
>
>
>
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