[lttng-dev] Assertion tgt_fc failed when trying to trace callstack-user

Francis Deslauriers francis.deslauriers at efficios.com
Mon Aug 2 08:56:17 EDT 2021

Hi Evan,

On 8/1/21 5:11 AM, Evan Galea via lttng-dev wrote:
> Hi there
> Thanks for help on my previous issue. I was able to get 
> callstack-user to work and see it in my traces. However, in order to 
> get it to run I needed to enable-event --kernel all. Is it necessary 
> to have all kernel events enabled to run callstack-user? Or is it just 
> one specific event?
> When I try to run it without enabling all kernel events the command is 
> accepted and it runs but I get the following error when trying to view 
> my traces:
>  (╯°□°)╯︵ ┻━┻ ctf-meta-update-value-storing-indexes.c:65: 
> update_field_class_stored_value_index(): Assertion `tgt_fc` failed.
> Aborted (core dumped)
> What does this error mean? Should I just continue to enable all kernel 
> events?

It's a Babeltrace 2 error. Now, we need to find out if the root cause is 
the LTTng kernel tracer or Babeltrace2 itself.

What is the "one specific event" you're enabling that seems to cause 
this issue?

Do you have access to a Babeltrace 1.5 build? if so, could you try to 
read that same trace using it?

Could you please share a small trace reproducing this issue?

What version of LTTng-tools, LTTng-Modules, and Babeltrace2 are you using?



> My current command setup, not sure if relevant
> lttng create &&
> lttng enable-channel mychannel --subbuf-size 100000000
> lttng enable-event --kernel --all &&
> lttng add-context -u -t vpid -t vtid -t procname &&
> lttng add-context --kernel --type callstack-user &&
> lttng add-context --kernel --type callstack-kernel &&
> lttng enable-event --jul jello
> again thank you for your time
> Evan Galea
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
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