babeltrace2-source.text.dmesg(7) — Linux manual page


BABELTRACE2-SOURCE()                                    BABELTRACE2-SOURCE()

NAME         top

       babeltrace2-source.text.dmesg - Babeltrace 2's Linux kernel ring
       buffer source component class

DESCRIPTION         top

       A Babeltrace 2 source.text.dmesg message iterator reads the lines of
       a Linux kernel ring buffer, as printed by the dmesg(1) tool, and
       emits corresponding event messages.

           Linux kernel ring buffer
           lines (file or standard input)
             |   +----------------+
             |   | src.text.dmesg |
             '-->|                |
                 |            out @--> Messages (single stream)

       See babeltrace2-intro(7) to learn more about the Babeltrace 2 project
       and its core concepts.

       A source.text.dmesg message iterator names the events it creates
       string. Each event contain a single payload string field named str
       which contains the corresponding ring buffer line.

       By default, a source.text.dmesg message iterator reads the lines of
       the standard input stream. You can make the message iterator read the
       lines of a text file instead with the path parameter.

       By default, the message iterator tries to extract the timestamps of
       the kernel ring buffer lines and use them as the created events’s
       timestamps. A typical dmesg(1) line looks like this:

           [87166.510937] PM: Finishing wakeup.

       The [87166.510937] part is the timestamp to extract. When this
       information is available, the component creates a clock class which
       does NOT have the Unix epoch as its origin.

       You can make the message iterator not extract timestamps from lines
       with the no-extract-timestamp parameter.

           It is possible that the output of dmesg(1) contains unsorted
           lines, that is, their timestamps go back in time. You can see
           this with the --show-delta option of dmesg(1): some time
           differences can be negative.

           This is due to a 2019 change (see
           <>) to the kernel’s ring buffer

           As of this version, a source.text.dmesg message iterator requires
           that the input kernel ring buffer lines be sorted by timestamp
           (when they have timestamps), failing otherwise.


       no-extract-timestamp=yes [optional boolean]
           Do NOT extract timestamps from the kernel ring buffer lines: set
           the created event’s payload’s str field to the whole line,
           including any timestamp prefix.

       path=PATH [optional string]
           Read the kernel ring buffer lines from the file PATH instead of
           the standard input stream.

PORTS         top

           | src.text.dmesg |
           |                |
           |            out @

           Single output port.

BUGS         top

       If you encounter any issue or usability problem, please report it on
       the Babeltrace bug tracker (see

RESOURCES         top

       The Babeltrace project shares some communication channels with the
       LTTng project (see <>).

       ·   Babeltrace website (see <>)

       ·   Mailing list (see <>) for support and

       ·   IRC channel (see <irc://>): #lttng on

       ·   Bug tracker (see <>)

       ·   Git repository (see <>)

       ·   GitHub project (see <>)

       ·   Continuous integration (see

       ·   Code review (see <>)

AUTHORS         top

       The Babeltrace 2 project is the result of hard work by many regular
       developers and occasional contributors.

       The current project maintainer is Jérémie Galarneau

COPYRIGHT         top

       This component class is part of the Babeltrace 2 project.

       Babeltrace is distributed under the MIT license (see

SEE ALSO         top

       babeltrace2-plugin-text(7), babeltrace2-intro(7)

COLOPHON         top

       This page is part of the babeltrace (trace read and write libraries
       and a trace converter) project.  Information about the project can be
       found at ⟨⟩.  If you have a bug
       report for this manual page, send it to
       This page was obtained from the project's upstream Git repository
       ⟨git://⟩ on 2020-07-14.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-08.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to


Pages that refer to this page: babeltrace2(1)babeltrace2-log(1)babeltrace2-plugin-text(7)