journald: bring order of MaxLevelXYZ= setting explanations in sync with listed names

[thirdparty/systemd.git] / man / repart.d.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="repart.d" conditional='ENABLE_REPART'
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>repart.d</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>repart.d</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>repart.d</refname>
    <refpurpose>Partition Definition Files for Automatic Boot-Time Repartitioning</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><simplelist>
      <member><filename>/etc/repart.d/*.conf</filename></member>
      <member><filename>/run/repart.d/*.conf</filename></member>
      <member><filename>/usr/lib/repart.d/*.conf</filename></member>
    </simplelist></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><filename>repart.d/*.conf</filename> files describe basic properties of partitions of block
    devices of the local system. They may be used to declare types, names and sizes of partitions that shall
    exist. The
    <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    service reads these files and attempts to add new partitions currently missing and enlarge existing
    partitions according to these definitions. Operation is generally incremental, i.e. when applied, what
    exists already is left intact, and partitions are never shrunk, moved or deleted.</para>

    <para>These definition files are useful for implementing operating system images that are prepared and
    delivered with minimally sized images (for example lacking any state or swap partitions), and which on
    first boot automatically take possession of any remaining disk space following a few basic rules.</para>

    <para>Currently, support for partition definition files is only implemented for GPT partition
    tables.</para>

    <para>Partition files are generally matched against any partitions already existing on disk in a simple
    algorithm: the partition files are sorted by their filename (ignoring the directory prefix), and then
    compared in order against existing partitions matching the same partition type UUID. Specifically, the
    first existing partition with a specific partition type UUID is assigned the first definition file with
    the same partition type UUID, and the second existing partition with a specific type UUID the second
    partition file with the same type UUID, and so on. Any left-over partition files that have no matching
    existing partition are assumed to define new partition that shall be created. Such partitions are
    appended to the end of the partition table, in the order defined by their names utilizing the first
    partition slot greater than the highest slot number currently in use. Any existing partitions that have
    no matching partition file are left as they are.</para>

    <para>Note that these definitions may only be used to create and initialize new partitions or to grow
    existing ones. In the latter case it will not grow the contained files systems however; separate
    mechanisms, such as
    <citerefentry><refentrytitle>systemd-growfs</refentrytitle><manvolnum>8</manvolnum></citerefentry> may be
    used to grow the file systems inside of these partitions. Partitions may also be marked for automatic
    growing via the <varname>GrowFileSystem=</varname> setting, in which case the file system is grown on
    first mount by tools that respect this flag. See below for details.</para>
  </refsect1>

  <refsect1>
    <title>[Partition] Section Options</title>

    <variablelist>
      <varlistentry>
        <term><varname>Type=</varname></term>

        <listitem><para>The GPT partition type UUID to match. This may be a GPT partition type UUID such as
        <constant>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</constant>, or an identifier.
        Architecture specific partition types can use one of these architecture identifiers:
        <constant>alpha</constant>, <constant>arc</constant>, <constant>arm</constant> (32-bit),
        <constant>arm64</constant> (64-bit, aka aarch64), <constant>ia64</constant>,
        <constant>loongarch64</constant>, <constant>mips-le</constant>, <constant>mips64-le</constant>,
        <constant>parisc</constant>, <constant>ppc</constant>, <constant>ppc64</constant>,
        <constant>ppc64-le</constant>, <constant>riscv32</constant>, <constant>riscv64</constant>,
        <constant>s390</constant>, <constant>s390x</constant>, <constant>tilegx</constant>,
        <constant>x86</constant> (32-bit, aka i386) and <constant>x86-64</constant> (64-bit, aka amd64).
        </para>

        <para>The supported identifiers are:</para>

        <table>
          <title>GPT partition type identifiers</title>

          <tgroup cols='2' align='left' colsep='1' rowsep='1'>
            <colspec colname="name" />
            <colspec colname="explanation" />

            <thead>
              <row>
                <entry>Identifier</entry>
                <entry>Explanation</entry>
              </row>
            </thead>

            <tbody>
              <row>
                <entry><constant>esp</constant></entry>
                <entry>EFI System Partition</entry>
              </row>

              <row>
                <entry><constant>xbootldr</constant></entry>
                <entry>Extended Boot Loader Partition</entry>
              </row>

              <row>
                <entry><constant>swap</constant></entry>
                <entry>Swap partition</entry>
              </row>

              <row>
                <entry><constant>home</constant></entry>
                <entry>Home (<filename>/home/</filename>) partition</entry>
              </row>

              <row>
                <entry><constant>srv</constant></entry>
                <entry>Server data (<filename>/srv/</filename>) partition</entry>
              </row>

              <row>
                <entry><constant>var</constant></entry>
                <entry>Variable data (<filename>/var/</filename>) partition</entry>
              </row>

              <row>
                <entry><constant>tmp</constant></entry>
                <entry>Temporary data (<filename>/var/tmp/</filename>) partition</entry>
              </row>

              <row>
                <entry><constant>linux-generic</constant></entry>
                <entry>Generic Linux file system partition</entry>
              </row>

              <row>
                <entry><constant>root</constant></entry>
                <entry>Root file system partition type appropriate for the local architecture (an alias for an architecture root file system partition type listed below, e.g. <constant>root-x86-64</constant>)</entry>
              </row>

              <row>
                <entry><constant>root-verity</constant></entry>
                <entry>Verity data for the root file system partition for the local architecture</entry>
              </row>

              <row>
                <entry><constant>root-verity-sig</constant></entry>
                <entry>Verity signature data for the root file system partition for the local architecture</entry>
              </row>

              <row>
                <entry><constant>root-secondary</constant></entry>
                <entry>Root file system partition of the secondary architecture of the local architecture (usually the matching 32-bit architecture for the local 64-bit architecture)</entry>
              </row>

              <row>
                <entry><constant>root-secondary-verity</constant></entry>
                <entry>Verity data for the root file system partition of the secondary architecture</entry>
              </row>

              <row>
                <entry><constant>root-secondary-verity-sig</constant></entry>
                <entry>Verity signature data for the root file system partition of the secondary architecture</entry>
              </row>

              <row>
                <entry><constant>root-{arch}</constant></entry>
                <entry>Root file system partition of the given architecture (such as <constant>root-x86-64</constant> or <constant>root-riscv64</constant>)</entry>
              </row>

              <row>
                <entry><constant>root-{arch}-verity</constant></entry>
                <entry>Verity data for the root file system partition of the given architecture</entry>
              </row>

              <row>
                <entry><constant>root-{arch}-verity-sig</constant></entry>
                <entry>Verity signature data for the root file system partition of the given architecture</entry>
              </row>

              <row>
                <entry><constant>usr</constant></entry>
                <entry><filename>/usr/</filename> file system partition type appropriate for the local architecture (an alias for an architecture <filename>/usr/</filename> file system partition type listed below, e.g. <constant>usr-x86-64</constant>)</entry>
              </row>

              <row>
                <entry><constant>usr-verity</constant></entry>
                <entry>Verity data for the <filename>/usr/</filename> file system partition for the local architecture</entry>
              </row>

              <row>
                <entry><constant>usr-verity-sig</constant></entry>
                <entry>Verity signature data for the <filename>/usr/</filename> file system partition for the local architecture</entry>
              </row>

              <row>
                <entry><constant>usr-secondary</constant></entry>
                <entry><filename>/usr/</filename> file system partition of the secondary architecture of the local architecture (usually the matching 32-bit architecture for the local 64-bit architecture)</entry>
              </row>

              <row>
                <entry><constant>usr-secondary-verity</constant></entry>
                <entry>Verity data for the <filename>/usr/</filename> file system partition of the secondary architecture</entry>
              </row>

              <row>
                <entry><constant>usr-secondary-verity-sig</constant></entry>
                <entry>Verity signature data for the <filename>/usr/</filename> file system partition of the secondary architecture</entry>
              </row>

              <row>
                <entry><constant>usr-{arch}</constant></entry>
                <entry><filename>/usr/</filename> file system partition of the given architecture</entry>
              </row>

              <row>
                <entry><constant>usr-{arch}-verity</constant></entry>
                <entry>Verity data for the <filename>/usr/</filename> file system partition of the given architecture</entry>
              </row>

              <row>
                <entry><constant>usr-{arch}-verity-sig</constant></entry>
                <entry>Verity signature data for the <filename>/usr/</filename> file system partition of the given architecture</entry>
              </row>
            </tbody>
          </tgroup>
        </table>

        <para>This setting defaults to <constant>linux-generic</constant>.</para>

        <para>Most of the partition type UUIDs listed above are defined in the <ulink
        url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions
        Specification</ulink>.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Label=</varname></term>

        <listitem><para>The textual label to assign to the partition if none is assigned yet. Note that this
        setting is not used for matching. It is also not used when a label is already set for an existing
        partition. It is thus only used when a partition is newly created or when an existing one had a no
        label set (that is: an empty label). If not specified a label derived from the partition type is
        automatically used. Simple specifier expansion is supported, see below.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UUID=</varname></term>

        <listitem><para>The UUID to assign to the partition if none is assigned yet. Note that this
        setting is not used for matching. It is also not used when a UUID is already set for an existing
        partition. It is thus only used when a partition is newly created or when an existing one had a
        all-zero UUID set. If set to <literal>null</literal>, the UUID is set to all zeroes. If not specified
        a UUID derived from the partition type is automatically used.</para>

        <xi:include href="version-info.xml" xpointer="v246"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Priority=</varname></term>

        <listitem><para>A numeric priority to assign to this partition, in the range -2147483648…2147483647,
        with smaller values indicating higher priority, and higher values indicating smaller priority. This
        priority is used in case the configured size constraints on the defined partitions do not permit
        fitting all partitions onto the available disk space. If the partitions do not fit, the highest
        numeric partition priority of all defined partitions is determined, and all defined partitions with
        this priority are removed from the list of new partitions to create (which may be multiple, if the
        same priority is used for multiple partitions). The fitting algorithm is then tried again. If the
        partitions still do not fit, the now highest numeric partition priority is determined, and the
        matching partitions removed too, and so on. Partitions of a priority of 0 or lower are never
        removed. If all partitions with a priority above 0 are removed and the partitions still do not fit on
        the device the operation fails. Note that this priority has no effect on ordering partitions, for
        that use the alphabetical order of the filenames of the partition definition files. Defaults to
        0.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Weight=</varname></term>

        <listitem><para>A numeric weight to assign to this partition in the range 0…1000000. Available disk
        space is assigned the defined partitions according to their relative weights (subject to the size
        constraints configured with <varname>SizeMinBytes=</varname>, <varname>SizeMaxBytes=</varname>), so
        that a partition with weight 2000 gets double the space as one with weight 1000, and a partition with
        weight 333 a third of that. Defaults to 1000.</para>

        <para>The <varname>Weight=</varname> setting is used to distribute available disk space in an
        "elastic" fashion, based on the disk size and existing partitions. If a partition shall have a fixed
        size use both <varname>SizeMinBytes=</varname> and <varname>SizeMaxBytes=</varname> with the same
        value in order to fixate the size to one value, in which case the weight has no
        effect.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PaddingWeight=</varname></term>

        <listitem><para>Similar to <varname>Weight=</varname>, but sets a weight for the free space after the
        partition (the "padding"). When distributing available space the weights of all partitions and all
        defined padding is summed, and then each partition and padding gets the fraction defined by its
        weight. Defaults to 0, i.e. by default no padding is applied.</para>

        <para>Padding is useful if empty space shall be left for later additions or a safety margin at the
        end of the device or between partitions.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SizeMinBytes=</varname></term>
        <term><varname>SizeMaxBytes=</varname></term>

        <listitem><para>Specifies minimum and maximum size constraints in bytes. Takes the usual K, M, G, T,
        …  suffixes (to the base of 1024). If <varname>SizeMinBytes=</varname> is specified the partition is
        created at or grown to at least the specified size. If <varname>SizeMaxBytes=</varname> is specified
        the partition is created at or grown to at most the specified size. The precise size is determined
        through the weight value configured with <varname>Weight=</varname>, see above. When
        <varname>SizeMinBytes=</varname> is set equal to <varname>SizeMaxBytes=</varname> the configured
        weight has no effect as the partition is explicitly sized to the specified fixed value. Note that
        partitions are never created smaller than 4096 bytes, and since partitions are never shrunk the
        previous size of the partition (in case the partition already exists) is also enforced as lower bound
        for the new size. The values should be specified as multiples of 4096 bytes, and are rounded upwards
        (in case of <varname>SizeMinBytes=</varname>) or downwards (in case of
        <varname>SizeMaxBytes=</varname>) otherwise. If the backing device does not provide enough space to
        fulfill the constraints placing the partition will fail. For partitions that shall be created,
        depending on the setting of <varname>Priority=</varname> (see above) the partition might be dropped
        and the placing algorithm restarted. By default a minimum size constraint of 10M and no maximum size
        constraint is set.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PaddingMinBytes=</varname></term>
        <term><varname>PaddingMaxBytes=</varname></term>

        <listitem><para>Specifies minimum and maximum size constraints in bytes for the free space after the
        partition (the "padding"). Semantics are similar to <varname>SizeMinBytes=</varname> and
        <varname>SizeMaxBytes=</varname>, except that unlike partition sizes free space can be shrunk and can
        be as small as zero. By default no size constraints on padding are set, so that only
        <varname>PaddingWeight=</varname> determines the size of the padding applied.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CopyBlocks=</varname></term>

        <listitem><para>Takes a path to a regular file, block device node or directory, or the special value
        <literal>auto</literal>. If specified and the partition is newly created, the data from the specified
        path is written to the newly created partition, on the block level. If a directory is specified, the
        backing block device of the file system the directory is on is determined, and the data read directly
        from that. This option is useful to efficiently replicate existing file systems onto new partitions
        on the block level — for example to build a simple OS installer or an OS image builder.</para>

        <para>If the special value <literal>auto</literal> is specified, the source to copy from is
        automatically picked up from the running system (or the image specified with
        <option>--image=</option> — if used). A partition that matches both the configured partition type (as
        declared with <varname>Type=</varname> described above), and the currently mounted directory
        appropriate for that partition type is determined. For example, if the partition type is set to
        <literal>root</literal> the partition backing the root directory (<filename>/</filename>) is used as
        source to copy from — if its partition type is set to <literal>root</literal> as well. If the
        declared type is <literal>usr</literal> the partition backing <filename>/usr/</filename> is used as
        source to copy blocks from — if its partition type is set to <literal>usr</literal> too. The logic is
        capable of automatically tracking down the backing partitions for encrypted and Verity-enabled
        volumes. <literal>CopyBlocks=auto</literal> is useful for implementing "self-replicating" systems,
        i.e. systems that are their own installer.</para>

        <para>The file specified here must have a size that is a multiple of the basic block size 512 and not
        be empty. If this option is used, the size allocation algorithm is slightly altered: the partition is
        created at least as big as required to fit the data in, i.e. the data size is an additional minimum
        size value taken into consideration for the allocation algorithm, similar to and in addition to the
        <varname>SizeMin=</varname> value configured above.</para>

        <para>This option has no effect if the partition it is declared for already exists, i.e. existing
        data is never overwritten. Note that the data is copied in before the partition table is updated,
        i.e. before the partition actually is persistently created. This provides robustness: it is
        guaranteed that the partition either doesn't exist or exists fully populated; it is not possible that
        the partition exists but is not or only partially populated.</para>

        <para>This option cannot be combined with <varname>Format=</varname> or
        <varname>CopyFiles=</varname>.</para>

        <xi:include href="version-info.xml" xpointer="v246"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Format=</varname></term>

        <listitem><para>Takes a file system name, such as <literal>ext4</literal>, <literal>btrfs</literal>,
        <literal>xfs</literal>, <literal>vfat</literal>, <literal>erofs</literal>,
        <literal>squashfs</literal> or the special value <literal>swap</literal>. If specified and the partition
        is newly created it is formatted with the specified file system (or as swap device). The file system
        UUID and label are automatically derived from the partition UUID and label. If this option is used,
        the size allocation algorithm is slightly altered: the partition is created at least as big as
        required for the minimal file system of the specified type (or 4KiB if the minimal size is not
        known).</para>

        <para>This option has no effect if the partition already exists.</para>

        <para>Similarly to the behaviour of <varname>CopyBlocks=</varname>, the file system is formatted
        before the partition is created, ensuring that the partition only ever exists with a fully
        initialized file system.</para>

        <para>This option cannot be combined with <varname>CopyBlocks=</varname>.</para>

        <xi:include href="version-info.xml" xpointer="v247"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CopyFiles=</varname></term>

        <listitem><para>Takes a pair of colon separated absolute file system paths. The first path refers to
        a source file or directory on the host, the second path refers to a target in the file system of the
        newly created partition and formatted file system. This setting may be used to copy files or
        directories from the host into the file system that is created due to the <varname>Format=</varname>
        option. If <varname>CopyFiles=</varname> is used without <varname>Format=</varname> specified
        explicitly, <literal>Format=</literal> with a suitable default is implied (currently
        <literal>vfat</literal> for <literal>ESP</literal> and <literal>XBOOTLDR</literal> partitions, and
        <literal>ext4</literal> otherwise, but this may change in the future). This option may be used
        multiple times to copy multiple files or directories from host into the newly formatted file system.
        The colon and second path may be omitted in which case the source path is also used as the target
        path (relative to the root of the newly created file system). If the source path refers to a
        directory it is copied recursively.</para>

        <para>This option has no effect if the partition already exists: it cannot be used to copy additional
        files into an existing partition, it may only be used to populate a file system created anew.</para>

        <para>The copy operation is executed before the file system is registered in the partition table,
        thus ensuring that a file system populated this way only ever exists fully initialized.</para>

        <para>Note that <varname>CopyFiles=</varname> will skip copying files that aren't supported by the
        target filesystem (e.g symlinks, fifos, sockets and devices on vfat). When an unsupported file type
        is encountered, <command>systemd-repart</command> will skip copying this file and write a log message
        about it.</para>

        <para>Note that <command>systemd-repart</command> does not change the UIDs/GIDs of any copied files
        and directories. When running <command>systemd-repart</command> as an unprivileged user to build an
        image of files and directories owned by the same user, you can run <command>systemd-repart</command>
        in a user namespace with the current user mapped to the root user to make sure the files and
        directories in the image are owned by the root user.</para>

        <para>Note that when populating XFS filesystems with <command>systemd-repart</command> and loop
        devices are not available, populating XFS filesystems with files containing spaces, tabs or newlines
        might fail on old versions of
        <citerefentry project='man-pages'><refentrytitle>mkfs.xfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        due to limitations of its protofile format.</para>

        <para>Note that when populating XFS filesystems with <command>systemd-repart</command> and loop
        devices are not available, extended attributes will not be copied into generated XFS filesystems
        due to limitations <citerefentry project='man-pages'><refentrytitle>mkfs.xfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
        protofile format.</para>

        <para>This option cannot be combined with <varname>CopyBlocks=</varname>.</para>

        <para>When
        <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry> is
        invoked with the <option>--copy-source=</option> command line switch the file paths are taken
        relative to the specified directory. If <option>--copy-source=</option> is not used, but the
        <option>--image=</option> or <option>--root=</option> switches are used, the source paths are taken
        relative to the specified root directory or disk image root.</para>

        <xi:include href="version-info.xml" xpointer="v247"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ExcludeFiles=</varname></term>
        <term><varname>ExcludeFilesTarget=</varname></term>

        <listitem><para>Takes an absolute file system path referring to a source file or directory on the
        host. This setting may be used to exclude files or directories from the host from being copied into
        the file system when <varname>CopyFiles=</varname> is used. This option may be used multiple times to
        exclude multiple files or directories from host from being copied into the newly formatted file
        system.</para>

        <para>If the path is a directory and ends with <literal>/</literal>, only the directory's
        contents are excluded but not the directory itself. If the path is a directory and does not end with
        <literal>/</literal>, both the directory and its contents are excluded.</para>

        <para><varname>ExcludeFilesTarget=</varname> is like <varname>ExcludeFiles=</varname> except that
        instead of excluding the path on the host from being copied into the partition, we exclude any files
        and directories from being copied into the given path in the partition.</para>

        <para>When
        <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        is invoked with the <option>--image=</option> or <option>--root=</option> command line switches the
        paths specified are taken relative to the specified root directory or disk image root.
        </para>

        <xi:include href="version-info.xml" xpointer="v254"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MakeDirectories=</varname></term>

        <listitem><para>Takes one or more absolute paths, separated by whitespace, each declaring a directory
        to create within the new file system. Behaviour is similar to <varname>CopyFiles=</varname>, but
        instead of copying in a set of files this just creates the specified directories with the default
        mode of 0755 owned by the root user and group, plus all their parent directories (with the same
        ownership and access mode). To configure directories with different ownership or access mode, use
        <varname>CopyFiles=</varname> and specify a source tree to copy containing appropriately
        owned/configured directories. This option may be used more than once to create multiple
        directories. When <varname>CopyFiles=</varname> and <varname>MakeDirectories=</varname> are used
        together the former is applied first. If a directory listed already exists no operation is executed
        (in particular, the ownership/access mode of the directories is left as is).</para>

        <para>The primary use case for this option is to create a minimal set of directories that may be
        mounted over by other partitions contained in the same disk image. For example, a disk image where
        the root file system is formatted at first boot might want to automatically pre-create
        <filename>/usr/</filename> in it this way, so that the <literal>usr</literal> partition may
        over-mount it.</para>

        <para>Consider using
        <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        with its <option>--image=</option> option to pre-create other, more complex directory hierarchies (as
        well as other inodes) with fine-grained control of ownership, access modes and other file
        attributes.</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Subvolumes=</varname></term>

        <listitem><para>Takes one or more absolute paths, separated by whitespace, each declaring a directory
        that should be a subvolume within the new file system. This option may be used more than once to
        specify multiple directories. Note that this setting does not create the directories themselves, that
        can be configured with <varname>MakeDirectories=</varname> and <varname>CopyFiles=</varname>.</para>

        <para>Note that this option only takes effect if the target filesystem supports subvolumes, such as
        <literal>btrfs</literal>.</para>

        <para>Note that due to limitations of <literal>mkfs.btrfs</literal>, this option is only supported
        when running with <option>--offline=no</option>.</para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultSubvolume=</varname></term>

        <listitem><para>Takes an absolute path specifying the default subvolume within the new filesystem.
        Note that this setting does not create the subvolume itself, that can be configured with
        <varname>Subvolumes=</varname>.</para>

        <para>Note that this option only takes effect if the target filesystem supports subvolumes, such as
        <literal>btrfs</literal>.</para>

        <para>Note that due to limitations of <literal>mkfs.btrfs</literal>, this option is only supported
        when running with <option>--offline=no</option>.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Encrypt=</varname></term>

        <listitem><para>Takes one of <literal>off</literal>, <literal>key-file</literal>,
        <literal>tpm2</literal> and <literal>key-file+tpm2</literal> (alternatively, also accepts a boolean
        value, which is mapped to <literal>off</literal> when false, and <literal>key-file</literal> when
        true). Defaults to <literal>off</literal>. If not <literal>off</literal> the partition will be
        formatted with a LUKS2 superblock, before the blocks configured with <varname>CopyBlocks=</varname>
        are copied in or the file system configured with <varname>Format=</varname> is created.</para>

        <para>The LUKS2 UUID is automatically derived from the partition UUID in a stable fashion. If
        <literal>key-file</literal> or <literal>key-file+tpm2</literal> is used, a key is added to the LUKS2
        superblock, configurable with the <option>--key-file=</option> option to
        <command>systemd-repart</command>. If <literal>tpm2</literal> or <literal>key-file+tpm2</literal> is
        used, a key is added to the LUKS2 superblock that is enrolled to the local TPM2 chip, as configured
        with the <option>--tpm2-device=</option> and <option>--tpm2-pcrs=</option> options to
        <command>systemd-repart</command>.</para>

        <para>When used this slightly alters the size allocation logic as the implicit, minimal size limits
        of <varname>Format=</varname> and <varname>CopyBlocks=</varname> are increased by the space necessary
        for the LUKS2 superblock (see above).</para>

        <para>This option has no effect if the partition already exists.</para>

        <xi:include href="version-info.xml" xpointer="v247"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Verity=</varname></term>

        <listitem><para>Takes one of <literal>off</literal>, <literal>data</literal>,
        <literal>hash</literal> or <literal>signature</literal>. Defaults to <literal>off</literal>. If set
        to <literal>off</literal> or <literal>data</literal>, the partition is populated with content as
        specified by <varname>CopyBlocks=</varname> or <varname>CopyFiles=</varname>. If set to
        <literal>hash</literal>, the partition will be populated with verity hashes from the matching verity
        data partition. If set to <literal>signature</literal>, the partition will be populated with a JSON
        object containing a signature of the verity root hash of the matching verity hash partition.</para>

        <para>A matching verity partition is a partition with the same verity match key (as configured with
        <varname>VerityMatchKey=</varname>).</para>

        <para>If not explicitly configured, the data partition's UUID will be set to the first 128
        bits of the verity root hash. Similarly, if not configured, the hash partition's UUID will be set to
        the final 128 bits of the verity root hash. The verity root hash itself will be included in the
        output of <command>systemd-repart</command>.</para>

        <para>This option has no effect if the partition already exists.</para>

        <para>Usage of this option in combination with <varname>Encrypt=</varname> is not supported.</para>

        <para>For each unique <varname>VerityMatchKey=</varname> value, a single verity data partition
        (<literal>Verity=data</literal>) and a single verity hash partition (<literal>Verity=hash</literal>)
        must be defined.</para>

        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>VerityMatchKey=</varname></term>

        <listitem><para>Takes a short, user-chosen identifier string. This setting is used to find sibling
        verity partitions for the current verity partition. See the description for
        <varname>Verity=</varname>.</para>

        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>VerityDataBlockSizeBytes=</varname></term>

        <listitem><para>Configures the data block size of the generated verity hash partition. Must be between 512 and
        4096 bytes and must be a power of 2. Defaults to the sector size if configured explicitly, or the underlying
        block device sector size, or 4K if systemd-repart is not operating on a block device.
        </para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>VerityHashBlockSizeBytes=</varname></term>

        <listitem><para>Configures the hash block size of the generated verity hash partition. Must be between 512 and
        4096 bytes and must be a power of 2. Defaults to the sector size if configured explicitly, or the underlying
        block device sector size, or 4K if systemd-repart is not operating on a block device.
        </para>

        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FactoryReset=</varname></term>

        <listitem><para>Takes a boolean argument. If specified the partition is marked for removal during a
        factory reset operation. This functionality is useful to implement schemes where images can be reset
        into their original state by removing partitions and creating them anew. Defaults to off.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Flags=</varname></term>

        <listitem><para>Configures the 64-bit GPT partition flags field to set for the partition when creating
        it. This option has no effect if the partition already exists. If not specified the flags values is
        set to all zeroes, except for the three bits that can also be configured via
        <varname>NoAuto=</varname>, <varname>ReadOnly=</varname> and <varname>GrowFileSystem=</varname>; see
        below for details on the defaults for these three flags. Specify the flags value in hexadecimal (by
        prefixing it with <literal>0x</literal>), binary (prefix <literal>0b</literal>) or decimal (no
        prefix).</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NoAuto=</varname></term>
        <term><varname>ReadOnly=</varname></term>
        <term><varname>GrowFileSystem=</varname></term>

        <listitem><para>Configures the No-Auto, Read-Only and Grow-File-System partition flags (bit 63, 60
        and 59) of the partition table entry, as defined by the <ulink
        url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>. Only
        available for partition types supported by the specification. This option is a friendly way to set
        bits 63, 60 and 59 of the partition flags value without setting any of the other bits, and may be set
        via <varname>Flags=</varname> too, see above.</para>

        <para>If <varname>Flags=</varname> is used in conjunction with one or more of
        <varname>NoAuto=</varname>/<varname>ReadOnly=</varname>/<varname>GrowFileSystem=</varname> the latter
        control the value of the relevant flags, i.e. the high-level settings
        <varname>NoAuto=</varname>/<varname>ReadOnly=</varname>/<varname>GrowFileSystem=</varname> override
        the relevant bits of the low-level setting <varname>Flags=</varname>.</para>

        <para>Note that the three flags affect only automatic partition mounting, as implemented by
        <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        or the <option>--image=</option> option of various commands (such as
        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>). It
        has no effect on explicit mounts, such as those done via <citerefentry
        project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry> or
        <citerefentry
        project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

        <para>If both bit 50 and 59 are set for a partition (i.e. the partition is marked both read-only and
        marked for file system growing) the latter is typically without effect: the read-only flag takes
        precedence in most tools reading these flags, and since growing the file system involves writing to
        the partition it is consequently ignored.</para>

        <para><varname>NoAuto=</varname> defaults to off. <varname>ReadOnly=</varname> defaults to on for
        Verity partition types, and off for all others. <varname>GrowFileSystem=</varname> defaults to on for
        all partition types that support it, except if the partition is marked read-only (and thus
        effectively, defaults to off for Verity partitions).</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SplitName=</varname></term>

        <listitem><para>Configures the suffix to append to split artifacts when the <option>--split</option>
        option of
        <citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry> is
        used. Simple specifier expansion is supported, see below. Defaults to <literal>%t</literal>. To
        disable split artifact generation for a partition, set <varname>SplitName=</varname> to
        <literal>-</literal>.</para>

        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Minimize=</varname></term>

        <listitem><para>Takes one of <literal>off</literal>, <literal>best</literal>, and
        <literal>guess</literal> (alternatively, also accepts a boolean value, which is mapped to
        <literal>off</literal> when false, and <literal>best</literal> when true). Defaults to
        <literal>off</literal>. If set to <literal>best</literal>, the partition will have the minimal size
        required to store the sources configured with <varname>CopyFiles=</varname>. <literal>best</literal>
        is currently only supported for read-only filesystems. If set to <literal>guess</literal>, the
        partition is created at least as big as required to store the sources configured with
        <varname>CopyFiles=</varname>. Note that unless the filesystem is a read-only filesystem,
        <command>systemd-repart</command> will have to populate the filesystem twice to guess the minimal
        required size, so enabling this option might slow down repart when populating large partitions.
        </para>

        <xi:include href="version-info.xml" xpointer="v253"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MountPoint=</varname></term>

        <listitem><para>Specifies where and how the partition should be mounted. Takes at least one and at
        most two fields separated with a colon (<literal>:</literal>). The first field specifies where the
        partition should be mounted. The second field specifies extra mount options to append to the default
        mount options. These fields correspond to the second and fourth column of the
        <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        format. This setting may be specified multiple times to mount the partition multiple times. This can
        be used to add mounts for different btrfs subvolumes located on the same btrfs partition.</para>

        <para>Note that this setting is only taken into account when <option>--generate-fstab=</option> is
        specified on the <command>systemd-repart</command> command line.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EncryptedVolume=</varname></term>

        <listitem><para>Specify how the encrypted partition should be set up. Takes at least one and at most
        three fields separated with a colon (<literal>:</literal>). The first field specifies the encrypted
        volume name under <filename>/dev/mapper/</filename>. If not specified, <literal>luks-UUID</literal>
        will be used where <literal>UUID</literal> is the LUKS UUID. The second field specifies the keyfile
        to use following the same format as specified in crypttab. The third field specifies a
        comma-delimited list of crypttab options. These fields correspond to the first, third and fourth
        column of the
        <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum></citerefentry> format.
        </para>

        <para>Note that this setting is only taken into account when <option>--generate-crypttab=</option>
        is specified on the <command>systemd-repart</command> command line.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Specifiers</title>

    <para>Specifiers may be used in the <varname>Label=</varname>, <varname>CopyBlocks=</varname>,
    <varname>CopyFiles=</varname>, <varname>MakeDirectories=</varname>, <varname>SplitName=</varname>
    settings. The following expansions are understood:</para>
      <table class='specifiers'>
        <title>Specifiers available</title>
        <tgroup cols='3' align='left' colsep='1' rowsep='1'>
          <colspec colname="spec" />
          <colspec colname="mean" />
          <colspec colname="detail" />
          <thead>
            <row>
              <entry>Specifier</entry>
              <entry>Meaning</entry>
              <entry>Details</entry>
            </row>
          </thead>
          <tbody>
            <xi:include href="standard-specifiers.xml" xpointer="a"/>
            <xi:include href="standard-specifiers.xml" xpointer="A"/>
            <xi:include href="standard-specifiers.xml" xpointer="b"/>
            <xi:include href="standard-specifiers.xml" xpointer="B"/>
            <xi:include href="standard-specifiers.xml" xpointer="H"/>
            <xi:include href="standard-specifiers.xml" xpointer="l"/>
            <xi:include href="standard-specifiers.xml" xpointer="m"/>
            <xi:include href="standard-specifiers.xml" xpointer="M"/>
            <xi:include href="standard-specifiers.xml" xpointer="o"/>
            <xi:include href="standard-specifiers.xml" xpointer="v"/>
            <xi:include href="standard-specifiers.xml" xpointer="w"/>
            <xi:include href="standard-specifiers.xml" xpointer="W"/>
            <xi:include href="standard-specifiers.xml" xpointer="T"/>
            <xi:include href="standard-specifiers.xml" xpointer="V"/>
            <xi:include href="standard-specifiers.xml" xpointer="percent"/>
          </tbody>
        </tgroup>
      </table>

    <para>Additionally, for the <varname>SplitName=</varname> setting, the following specifiers are also
    understood:</para>
      <table class='specifiers'>
        <title>Specifiers available</title>
        <tgroup cols='3' align='left' colsep='1' rowsep='1'>
          <colspec colname="spec" />
          <colspec colname="mean" />
          <colspec colname="detail" />
          <thead>
            <row>
              <entry>Specifier</entry>
              <entry>Meaning</entry>
              <entry>Details</entry>
            </row>
          </thead>
          <tbody>
            <row id='T'>
              <entry><literal>%T</literal></entry>
              <entry>Partition Type UUID</entry>
              <entry>The partition type UUID, as configured with <varname>Type=</varname></entry>
            </row>
            <row id='t'>
              <entry><literal>%t</literal></entry>
              <entry>Partition Type Identifier</entry>
              <entry>The partition type identifier corresponding to the partition type UUID</entry>
            </row>
            <row id='U'>
              <entry><literal>%U</literal></entry>
              <entry>Partition UUID</entry>
              <entry>The partition UUID, as configured with <varname>UUID=</varname></entry>
            </row>
            <row id='n'>
              <entry><literal>%n</literal></entry>
              <entry>Partition Number</entry>
              <entry>The partition number assigned to the partition</entry>
            </row>
          </tbody>
        </tgroup>
      </table>
  </refsect1>

  <refsect1>
    <title>Environment</title>

    <para>Extra filesystem formatting options can be provided using filesystem-specific environment variables:
    <varname>$SYSTEMD_REPART_MKFS_OPTIONS_BTRFS</varname>, <varname>$SYSTEMD_REPART_MKFS_OPTIONS_XFS</varname>,
    <varname>$SYSTEMD_REPART_MKFS_OPTIONS_VFAT</varname>, <varname>$SYSTEMD_REPART_MKFS_OPTIONS_EROFS</varname>,
    and <varname>$SYSTEMD_REPART_MKFS_OPTIONS_SQUASHFS</varname>. Each variable accepts valid
    <command>mkfs.<replaceable>filesystem</replaceable></command> command-line arguments.
    The content of those variables is passed as-is to the command, without any verification.
    </para>

  </refsect1>

  <refsect1>
    <title>Examples</title>

    <example>
      <title>Grow the root partition to the full disk size at first boot</title>

      <para>With the following file the root partition is automatically grown to the full disk if possible
      during boot.</para>

      <para><programlisting># /usr/lib/repart.d/50-root.conf
[Partition]
Type=root
</programlisting></para>
    </example>

    <example>
      <title>Create a swap and home partition automatically on boot, if missing</title>

      <para>The home partition gets all available disk space while the swap partition gets 1G at most and 64M
      at least. We set a priority > 0 on the swap partition to ensure the swap partition is not used if not
      enough space is available. For every three bytes assigned to the home partition the swap partition gets
      assigned one.</para>

      <para><programlisting># /usr/lib/repart.d/60-home.conf
[Partition]
Type=home
</programlisting></para>

      <para><programlisting># /usr/lib/repart.d/70-swap.conf
[Partition]
Type=swap
SizeMinBytes=64M
SizeMaxBytes=1G
Priority=1
Weight=333
</programlisting></para>
    </example>

    <example>
      <title>Create B partitions in an A/B Verity setup, if missing</title>

      <para>Let's say the vendor intends to update OS images in an A/B setup, i.e. with two root partitions
      (and two matching Verity partitions) that shall be used alternatingly during upgrades. To minimize
      image sizes the original image is shipped only with one root and one Verity partition (the "A" set),
      and the second root and Verity partitions (the "B" set) shall be created on first boot on the free
      space on the medium.</para>

      <para><programlisting># /usr/lib/repart.d/50-root.conf
[Partition]
Type=root
SizeMinBytes=512M
SizeMaxBytes=512M
</programlisting></para>

      <para><programlisting># /usr/lib/repart.d/60-root-verity.conf
[Partition]
Type=root-verity
SizeMinBytes=64M
SizeMaxBytes=64M
</programlisting></para>

      <para>The definitions above cover the "A" set of root partition (of a fixed 512M size) and Verity
      partition for the root partition (of a fixed 64M size). Let's use symlinks to create the "B" set of
      partitions, since after all they shall have the same properties and sizes as the "A" set.</para>

<para><programlisting># ln -s 50-root.conf /usr/lib/repart.d/70-root-b.conf
# ln -s 60-root-verity.conf /usr/lib/repart.d/80-root-verity-b.conf
</programlisting></para>
    </example>

     <example>
      <title>Create a data partition and corresponding verity partitions from a OS tree</title>

      <para>Assuming we have an OS tree at <filename index='false'>/var/tmp/os-tree</filename> that we want
      to package in a root partition together with matching verity partitions, we can do so as follows:
      </para>

      <para><programlisting># 50-root.conf
[Partition]
Type=root
CopyFiles=/var/tmp/os-tree
Verity=data
VerityMatchKey=root
Minimize=guess
</programlisting></para>

      <para><programlisting># 60-root-verity.conf
[Partition]
Type=root-verity
Verity=hash
VerityMatchKey=root
# Explicitly set the hash and data block size to 4K
VerityDataBlockSizeBytes=4096
VerityHashBlockSizeBytes=4096
Minimize=best
</programlisting></para>

<para><programlisting># 70-root-verity-sig.conf
[Partition]
Type=root-verity-sig
Verity=signature
VerityMatchKey=root
</programlisting></para>
    </example>

  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-repart</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
      <member><citerefentry project='man-pages'><refentrytitle>sfdisk</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-cryptenroll</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>

</refentry>