Adding upstream version 255.4.upstream/255.4

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

1 files changed, 171 insertions, 0 deletions

diff --git a/man/systemd.device.xml b/man/systemd.device.xml
new file mode 100644
index 0000000..529552e
--- /dev/null
+++ b/man/systemd.device.xml
@@ -0,0 +1,171 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!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.device">
+  <refentryinfo>
+    <title>systemd.device</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>systemd.device</refentrytitle>
+    <manvolnum>5</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>systemd.device</refname>
+    <refpurpose>Device unit configuration</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <para><filename><replaceable>device</replaceable>.device</filename></para>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>A unit configuration file whose name ends in <literal>.device</literal> encodes information about a
+    device unit as exposed in the
+    sysfs/<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> device
+    tree. This may be used to define dependencies between devices and other units.</para>
+
+    <para>This unit type has no specific options. See
+    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+    for the common options of all unit configuration files. The common
+    configuration items are configured in the generic
+    [Unit] and [Install]
+    sections. A separate [Device] section does not
+    exist, since no device-specific options may be configured.</para>
+
+    <para>systemd will dynamically create device units for all kernel devices that are marked with the
+    <literal>systemd</literal> udev tag (by default all block and network devices, and a few others). Note
+    that <emphasis>if <filename>systemd-udevd.service</filename> is not running, no device units will be
+    available (for example in a typical container)</emphasis>.</para>
+
+    <para>Device units are named after the <filename>/sys/</filename>
+    and <filename>/dev/</filename> paths they control. Example: the
+    device <filename index="false">/dev/sda5</filename> is exposed in
+    systemd as <filename>dev-sda5.device</filename>. For details about
+    the escaping logic used to convert a file system path to a unit
+    name see
+    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+    <para>To tag a udev device, use <literal>TAG+="systemd"</literal> in the udev rules file, see
+    <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details.
+    </para>
+
+    <para>Device units will be reloaded by systemd whenever the
+    corresponding device generates a <literal>changed</literal> event.
+    Other units can use <varname>ReloadPropagatedFrom=</varname> to react
+    to that event.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Automatic Dependencies</title>
+
+    <refsect2>
+      <title>Implicit Dependencies</title>
+
+      <para>Many unit types automatically acquire dependencies on device
+      units of devices they require. For example,
+      <filename>.socket</filename> unit acquire dependencies on the
+      device units of the network interface specified in
+      <varname>BindToDevice=</varname>. Similar, swap and mount units
+      acquire dependencies on the units encapsulating their backing
+      block devices.</para>
+    </refsect2>
+
+    <refsect2>
+      <title>Default Dependencies</title>
+
+      <para>There are no default dependencies for device units.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>The udev Database</title>
+
+    <para>Unit settings of device units may either be configured via unit files, or directly from the udev
+    database. The following udev device properties are understood by the service manager:</para>
+
+    <variablelist class='udev-directives'>
+      <varlistentry>
+        <term><varname>SYSTEMD_WANTS=</varname></term>
+        <term><varname>SYSTEMD_USER_WANTS=</varname></term>
+        <listitem><para>Adds dependencies of type <varname>Wants=</varname> from the device unit to the specified
+        units. <varname>SYSTEMD_WANTS=</varname> is read by the system service manager,
+        <varname>SYSTEMD_USER_WANTS=</varname> by user service manager instances. These properties may be used to
+        activate arbitrary units when a specific device becomes available.</para>
+
+        <para>Note that this and the other udev device properties are not taken into account unless the device is
+        tagged with the <literal>systemd</literal> tag in the udev database, because otherwise the device is not
+        exposed as a systemd unit (see above).</para>
+
+        <para>Note that systemd will only act on <varname>Wants=</varname> dependencies when a device first becomes
+        active. It will not act on them if they are added to devices that are already active. Use
+        <varname>SYSTEMD_READY=</varname> (see below) to configure when a udev device shall be considered active, and
+        thus when to trigger the dependencies.</para>
+
+        <!-- Note that we don't document here that we actually apply unit_name_mangle() to all specified names, since
+             that's kinda ugly, and people should instead specify correctly escaped names -->
+
+        <para>The specified property value should be a space-separated list of valid unit names. If a unit template
+        name is specified (that is, a unit name containing an <literal>@</literal> character indicating a unit name to
+        use for multiple instantiation, but with an empty instance name following the <literal>@</literal>), it will be
+        automatically instantiated by the device's <literal>sysfs</literal> path (that is: the path is escaped and
+        inserted as instance name into the template unit name). This is useful in order to instantiate a specific
+        template unit once for each device that appears and matches specific properties.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>SYSTEMD_ALIAS=</varname></term>
+        <listitem><para>Adds an additional alias name to the device
+        unit. This must be an absolute path that is automatically
+        transformed into a unit name. (See above.)</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>SYSTEMD_READY=</varname></term>
+        <listitem><para>If set to 0, systemd will consider this device unplugged even if it shows up in the udev
+        tree. If this property is unset or set to 1, the device will be considered plugged if it is visible in the udev
+        tree.</para>
+
+        <para>This option is useful for devices that initially show up in an uninitialized state in the tree, and for
+        which a <literal>changed</literal> event is generated the moment they are fully set up. Note that
+        <varname>SYSTEMD_WANTS=</varname> (see above) is not acted on as long as <varname>SYSTEMD_READY=0</varname> is
+        set for a device.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>ID_MODEL_FROM_DATABASE=</varname></term>
+        <term><varname>ID_MODEL=</varname></term>
+
+        <listitem><para>If set, this property is used as description
+        string for the device unit.</para></listitem>
+      </varlistentry>
+
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Options</title>
+
+    <para>Device unit files may include [Unit] and [Install] sections, which are described in
+    <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. No
+    options specific to this file type are supported.</para>
+  </refsect1>
+
+  <refsect1>
+      <title>See Also</title>
+      <para>
+        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+      </para>
+  </refsect1>
+
+</refentry>