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LIN1021-3005 : Babeltrace cannot handle negative clock offset

Created: Mar 6, 2022    Updated: Mar 28, 2022
Resolved Date: Mar 17, 2022
Previous ID: LINCCM-12992
Found In Version:
Fix Version:
Severity: Severe
Applicable for: Wind River Linux LTS 21
Component/s: Userspace


The customer requested a solution on Unix time, where systemd prevented that the system date started since 01-01-1970.

However, the proposed solution above introduced a new problem on lttng. When using lttng to view traces, it reports the following errors:

[error] ctf_clock_declaration_visit: unexpected unary expression for clock offset

[error] ctf_visitor_construct_metadata: clock declaration error

[error] Error in CTF metadata constructor -22

[warning] Unable to open trace metadata for path "/tmp/csrpTrace/trace/ust/uid/0/32-bit".

[warning] [Context] Cannot open_trace of format ctf at path /tmp/csrpTrace/trace/ust/uid/0/32-bit.

[warning] [Context] cannot open trace "/tmp/csrpTrace/trace/ust/uid/0/32-bit" from /tmp/csrpTrace/trace for reading.

[error] Cannot open any trace for reading.

[error] opening trace "/tmp/csrpTrace/trace" for reading.

[error] none of the specified trace paths could be opened.


In the lttng file "metadata", offset of clock is negative:


{ name = "monotonic"; uuid = "f18ef9e3-93fb-432b-bd8c-2c0da378d22c"; description = "Monotonic Clock"; freq = 1000000000; /* Frequency, in Hz */ /* clock value offset from Epoch is: offset * (1/freq) */ offset = -40; }


This is with lttng version 2.9.5

The customer suggest the following patch may be useful:
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