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

NAME | DESCRIPTION | INITIALIZATION PARAMETERS | PORTS | BUGS | RESOURCES | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON

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.

           Note
           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
           <https://lwn.net/Articles/780556/>) to the kernel’s ring
           buffer API.

           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.

INITIALIZATION PARAMETERS         top

       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 @
           +----------------+

   Output
       out
           Single output port.

BUGS         top

       If you encounter any issue or usability problem, please report it
       on the Babeltrace bug tracker (see
       <https://bugs.lttng.org/projects/babeltrace>).

RESOURCES         top

       The Babeltrace project shares some communication channels with
       the LTTng project (see <https://lttng.org/>).

       •   Babeltrace website (see <https://babeltrace.org/>)

       •   Mailing list (see <https://lists.lttng.org>) for support and
           development: lttng-dev@lists.lttng.org

       •   IRC channel (see <irc://irc.oftc.net/lttng>): #lttng on
           irc.oftc.net

       •   Bug tracker (see
           <https://bugs.lttng.org/projects/babeltrace>)

       •   Git repository (see
           <https://git.efficios.com/?p=babeltrace.git>)

       •   GitHub project (see <https://github.com/efficios/babeltrace>)

       •   Continuous integration (see
           <https://ci.lttng.org/view/Babeltrace/>)

       •   Code review (see
           <https://review.lttng.org/q/project:babeltrace>)

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
       <mailto:jeremie.galarneau@efficios.com>.

COPYRIGHT         top

       This component class is part of the Babeltrace 2 project.

       Babeltrace is distributed under the MIT license (see
       <https://opensource.org/licenses/MIT>).

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 ⟨http://www.efficios.com/babeltrace⟩.  If
       you have a bug report for this manual page, send it to
       lttng-dev@lists.lttng.org.  This page was obtained from the
       project's upstream Git repository
       ⟨git://git.efficios.com/babeltrace.git⟩ on 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-05-28.)  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
       man-pages@man7.org

                                                    BABELTRACE2-SOURCE()

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