[lttng-dev] lttng-dev Digest, Vol 60, Issue 31

[Jérémie Galarneau]

Hi Daniel,

The kernel modules are indeed not needed for userspace tracing.

I'm guessing you installed from source since the lttng libs don't seem
present in your path. Could tell us on which revision this is
happening?

Also, perhaps you could try Mathieu's recently commited fix? It may be
related.[1]

Regards,
Jérémie

[1] http://lists.lttng.org/pipermail/lttng-dev/2013-April/020064.html

On Thu, Apr 18, 2013 at 3:26 PM, Thibault, Daniel
<Daniel.Thibault at drdc-rddc.gc.ca> wrote:
>>   Absolutely: no patching required.
>
>    I decided to find out if the lttng-modules were required at all if one needs to do only user-space tracing.
>
>    I installed (on an otherwise lttng-virgin system) just the userspace-rcu, lttng-ust, and lttng-tools packages.  The lttng commands fail for the usual "can't find /usr/local/lib" reason, so I need to do not:
>
> $ lttng list -u
>
>    but rather
>
> $ LD_PRELOAD=/usr/local/lib/liblttng-ctl.so:/usr/local/lib/liblttng-ust-ctl.so lttng list -u
>
>    or
>
> $ LD_LIBRARY_PATH=/usr/local/lib lttng list -u
>
>    However, once I made the lttng-ust/doc/examples/easy-ust sample, I get a segmentation fault/core dump after starting the trace.
>
> $ LD_LIBRARY_PATH=/usr/local/lib lttng create usttrace
> Session usttrace created.
> Traces will be written in /home/daniel/lttng-traces/usttrace-20130418-150106
> $ LD_LIBRARY_PATH=/usr/local/lib lttng enable-event -u --all
> All UST events are enabled in channel channel0
> $ LD_LIBRARY_PATH=/usr/local/lib lttng start
> Tracing started for session usttrace
> $ LD_LIBRARY_PATH=/usr/local/lib ./sample
> Segmentation fault (core dumped)
>
>    Is this supposed to work or are the kernel modules required even when doing just pure user-space tracing?  I did get a partial trace on disk (just the channel0_0 and metadata files, no events in them).
>
> Daniel U. Thibault
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-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com