Adding upstream version 247.3.upstream/247.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 149 insertions, 0 deletions

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+<?xml version='1.0'?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="systemd-coredump" conditional='ENABLE_COREDUMP'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>systemd-coredump</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>systemd-coredump</refentrytitle>
+    <manvolnum>8</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>systemd-coredump</refname>
+    <refname>systemd-coredump.socket</refname>
+    <refname>systemd-coredump@.service</refname>
+    <refpurpose>Acquire, save and process core dumps</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <para><filename>/usr/lib/systemd/systemd-coredump</filename></para>
+    <para><filename>/usr/lib/systemd/systemd-coredump</filename> <option>--backtrace</option></para>
+    <para><filename>systemd-coredump@.service</filename></para>
+    <para><filename>systemd-coredump.socket</filename></para>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+    <para><filename>systemd-coredump@.service</filename> is a system service that can acquire core
+    dumps from the kernel and handle them in various ways. The <command>systemd-coredump</command>
+    executable does the actual work. It is invoked twice: once as the handler by the kernel, and the
+    second time in the <filename>systemd-coredump@.service</filename> to actually write the data to
+    the journal.</para>
+
+    <para>When the kernel invokes <command>systemd-coredump</command> to handle a core dump, it runs
+    in privileged mode, and will connect to the socket created by the
+    <filename>systemd-coredump.socket</filename> unit, which in turn will spawn an unprivileged
+    <filename>systemd-coredump@.service</filename> instance to process the core dump. Hence
+    <filename>systemd-coredump.socket</filename> and <filename>systemd-coredump@.service</filename>
+    are helper units which do the actual processing of core dumps and are subject to normal service
+    management.</para>
+
+    <para>Core dumps can be written to the journal or saved as a file. Once saved they can be retrieved
+    for further processing, for example in
+    <citerefentry project='man-pages'><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+    </para>
+
+    <para>By default, <command>systemd-coredump</command> will log the core dump including a backtrace
+    if possible to the journal and store the core dump itself in an external file in
+    <filename>/var/lib/systemd/coredump</filename>.</para>
+
+    <para>The behavior of a specific program upon reception of a signal is governed by a few
+    factors which are described in detail in
+    <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+    In particular, the core dump will only be processed when the related resource limits are sufficient.
+    </para>
+
+    <para>It is also possible to invoke <command>systemd-coredump</command> with
+    <option>--backtrace</option> option. In this case, <command>systemd-coredump</command> expects
+    a journal entry in the journal
+    <ulink url="https://www.freedesktop.org/wiki/Software/systemd/export">Journal Export Format</ulink>
+    on standard input. The entry should contain a <varname>MESSAGE=</varname> field and any additional
+    metadata fields the caller deems reasonable. <command>systemd-coredump</command> will append
+    additional metadata fields in the same way it does for core dumps received from the kernel. In
+    this mode, no core dump is stored in the journal.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Configuration</title>
+    <para>For programs started by <command>systemd</command>, process resource limits can be set by directive
+    <varname>LimitCORE=</varname>, see
+    <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+    </para>
+
+    <para>In order to be used by the kernel to handle core dumps,
+    <command>systemd-coredump</command> must be configured in
+    <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    parameter <varname>kernel.core_pattern</varname>. The syntax of this parameter is explained in
+    <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+    systemd installs the file <filename>/usr/lib/sysctl.d/50-coredump.conf</filename> which configures
+    <varname>kernel.core_pattern</varname> accordingly. This file may be masked or overridden to use a different
+    setting following normal
+    <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+    rules. If the sysctl configuration is modified, it must be updated in the kernel before it
+    takes effect, see
+    <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    and
+    <citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+    </para>
+
+    <para>In order to be used in the <option>--backtrace</option> mode, an appropriate backtrace
+    handler must be installed on the sender side. For example, in case of
+    <citerefentry project='die-net'><refentrytitle>python</refentrytitle><manvolnum>1</manvolnum></citerefentry>, this
+    means a <varname>sys.excepthook</varname> must be installed, see
+    <ulink url="https://github.com/keszybz/systemd-coredump-python">systemd-coredump-python</ulink>.
+    </para>
+
+    <para>The behavior of <command>systemd-coredump</command> itself is configured through the configuration file
+    <filename>/etc/systemd/coredump.conf</filename> and corresponding snippets
+    <filename>/etc/systemd/coredump.conf.d/*.conf</filename>, see
+    <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A new
+    instance of <command>systemd-coredump</command> is invoked upon receiving every core dump. Therefore, changes
+    in these files will take effect the next time a core dump is received.</para>
+
+    <para>Resources used by core dump files are restricted in two ways. Parameters like maximum size of acquired
+    core dumps and files can be set in files <filename>/etc/systemd/coredump.conf</filename> and snippets mentioned
+    above. In addition the storage time of core dump files is restricted by <command>systemd-tmpfiles</command>,
+    corresponding settings are by default in <filename>/usr/lib/tmpfiles.d/systemd.conf</filename>.</para>
+
+    <refsect2>
+      <title>Disabling coredump processing</title>
+
+      <para>To disable potentially resource-intensive processing by <command>systemd-coredump</command>,
+      set <programlisting>Storage=none
+ProcessSizeMax=0</programlisting> in
+      <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+      </para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Usage</title>
+    <para>Data stored in the journal can be viewed with
+    <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+    as usual.
+    <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+    can be used to retrieve saved core dumps independent of their location, to display information and to process
+    them e.g. by passing to the GNU debugger (gdb).</para>
+  </refsect1>
+
+  <refsect1>
+    <title>See Also</title>
+    <para>
+      <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+    </para>
+  </refsect1>
+</refentry>