[lttng-dev] Help needed: No UST events recorded

[Jonathan Rajotte-Julien]

Hi Moritz

What is your version of lttng-tools?

  lttng --version

Please run the `hello` executable using the LTTNG_UST_DEBUG env variable, while
tracing, and provide the output.

  pkill lttng-sessiond
  lttng-sessiond -b -vvv --verbose-consumer 2> /tmp/lttng-sessiond.log
  lttng create
  lttng enable-event -u -a
  lttng start
  LTTNG_UST_DEBUG=y ./hello
  lttng stop
  lttng destroy
  pkill lttng-sessiond

Please also provide the /tmp/lttng-sessiond.log file via pastebin.

I suspect that if you cross-compiled lttng-ust from the master branch that
lttng-tools is not using the same version, resulting in the application not
being able to register to the lttng-sessiond.

Cheers

On Mon, Aug 03, 2020 at 09:35:25AM +0000, PFLANZER Moritz via lttng-dev wrote:
> Hi all!
> 
> I'm struggling to get userspace tracing working on an aarch64 platform (busybox on top of Linux 5.4.24 kernel). I followed the guidelines in the docs and am currently using this example program for testing: https://github.com/lttng/lttng-ust/tree/master/doc/examples/hello-static-lib
> I cross-compiled lttng-ust and that example, but when I run the following commands on the platform no traces are recorded. If I use the same example on my x86 machine everything works as expected. (And kernelspace tracing is working on that aarch64 system.)
> 
> Any hints where I could start investigating the issue are welcome.
> 
> Regards,
> Moritz
> 
> ~ # pwd
> /root
> ~ # lttng create
> Spawning a session daemon
> Session auto-20200720-174509 created.
> Traces will be written in /root/lttng-traces/auto-20200720-174509
> ~ # lttng enable-event -au
> All UST events are enabled in channel channel0
> ~ # lttng start
> Tracing started for session auto-20200720-174509
> ~ # ./hello
> Hello, World!
> Tracing...  done.
> ~ # lttng destroy
> Session auto-20200720-174509 destroyed
> ~ # ll
> total 40
> -rwxr-xr-x    1 root     root         39280 Jul 20 17:44 hello*
> 
> 
> 
> Moritz Pflanzer
> Software Development Engineer
> 
> [cid:image001.png at 01D3BF6E.185110B0]
> 
> Räffelstrasse 28
> 
> 8045 Zürich
> E: moritz.pflanzer at hexagon.com<mailto:moritz.pflanzer at hexagon.com><mailto:carolin.siebert at hexagon.com>
> W: http://www.hexagongeosystems.com



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-- 
Jonathan Rajotte-Julien
EfficiOS