[lttng-dev] Error: opening metadata failed (LTTng on OpenWRT)

[Robin Michielsen]

Hi Jérémie,

Maybe I misunderstood how to create a session, but are the commands that I listed not sufficient for this?

•	lttng create
•	lttng enable-event --kernel --syscall open,close
•	lttng start

Kind regards,
Robin

-----Original Message-----
From: jeremie.galarneau at gmail.com [mailto:jeremie.galarneau at gmail.com] On Behalf Of Jérémie Galarneau
Sent: Tuesday, 14 November, 2017 17:09
To: Robin Michielsen
Cc: lttng-dev at lists.lttng.org
Subject: Re: [lttng-dev] Error: opening metadata failed (LTTng on OpenWRT)

Hi Robin,

Can you add the commands you use to create the session?

Thanks,
Jérémie

On 14 November 2017 at 04:41, Robin Michielsen <robin.michielsen.1 at gmail.com> wrote:
> Hi all,
>
>
>
> I am trying to trace the Linux kernel (system calls) using LTTng on a 
> platform that is running OpenWRT. I have cross compiled the latest 
> versions
> (2.10.x) of the lttng-modules, lttng-tools and lttng-ust packages and 
> installed these on my OpenWRT system. Now when I start a kernel trace 
> then the lttng tool returns the error "LTTng transport relay-metadata 
> not found /
> Error: Opening metadata failed". Does anybody know what might cause 
> this error, or have a hint on what to check?
>
>
>
> I have attached the captured output of ‘lttng-sessiond -vvv 
> --verbose-consumer’. Here is some more context:
>
> ·         MIPS platform running Linux 3.18.29
>
> ·         Package versions:
>
> o   lttng-modules-2.10.4
>
> o   lttng-tools-2.10.1
>
> o   lttng-ust-2.10.0
>
> ·         lsmod shows that the following modules have been loaded:
>
> o   lttng_clock
>
> o   lttng_lib_ring_buffer
>
> o   lttng_ring_buffer_client_discard
>
> o   lttng_statedump
>
> o   lttng_tracer
>
> ·         Commands to create and start a session:
>
> o   lttng create
>
> o   lttng enable-event --kernel --syscall open,close
>
> o   lttng start
>
>
>
> When ‘lttng start’ is called then lttng-sessiond’s debug output shows 
> “Closing metadata fd -1 (in trace_kernel_destroy_metadata() at 
> trace-kernel.c:569)” followed by “Sending response (size: 20, retcode:
> Opening metadata failed (45)) (in thread_manage_clients() at main.c:4641)”.
> I assume that the error that I’m seeing is because for some reason 
> metadata fd is being closed.
>
>
>
> Does anybody know what may cause this issue, or have a hint on to check?
>
>
>
> Kind regards,
>
> Robin
>
>
>
>
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>



--
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com