babeltrace master: trace-compass is unable to open trace with index

[Arnaud Fiorini]

Hi Felix,

There was indeed a bug in how CTF trace index is parsed in Trace Compass. I created a fix in https://github.com/eclipse-tracecompass/org.eclipse.tracecompass/pull/427

If you find another issue in Trace Compass, you can file a bug here instead: https://github.com/eclipse-tracecompass/org.eclipse.tracecompass/issues

Thank you,
Arnaud Fiorini

________________________________
From: MOESSBAUER, Felix via lttng-dev <lttng-dev at lists.lttng.org>
Sent: Wednesday, August 5, 2026 6:16 AM
To: MOESSBAUER, Felix via lttng-dev <lttng-dev at lists.lttng.org>
Subject: babeltrace master: trace-compass is unable to open trace with index

Hi,

the babeltrace version from the master branch (65fb4669f) is able to
create LTTng index files. However, these index files seem to be
incompatible with trace-compass.

On loading such a trace, trace-compass (incubator version, 0.18.0-
20260711-0558, or release 12.0.0) issues the following error message:

> Error initializing trace.
> org.eclipse.tracecompass.tmf.core.exceptions.TmfTraceException:
> Failed to allocate mapped byte buffer at 36 of size 416 on a
> file of size 176

I double checked the traces with babeltrace and
https://github.com/eepp/jacquesctf , which are both able to properly
read the traces.

For reproducing, run the
tests/plugins/sink.ctf.fs/test_create_lttng_index.py test and open any
of the generated CTF files in trace-compass. I explicitly tested and
reproduced it with "with-packets-ctf-2" and "no-packets-ctf-2".

The traces itself are valid, which can be proved by removing the index
file and successfully re-opening them in trace-compass.

PS: I'm pretty sure this is a trace-compass bug, but as I'm not a
member of the tracecompass-dev ML, I report it here. Feel free to
forward.

Best regards,
Felix Moessbauer

--
Siemens AG
Linux Expert Center
Friedrich-Ludwig-Bauer-Str. 3
85748 Garching, Germany

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