Adding upstream version 252.22.upstream/252.22

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

1 files changed, 283 insertions, 0 deletions

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+<?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-gpt-auto-generator" conditional='HAVE_BLKID'>
+
+  <refentryinfo>
+    <title>systemd-gpt-auto-generator</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>systemd-gpt-auto-generator</refentrytitle>
+    <manvolnum>8</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>systemd-gpt-auto-generator</refname>
+    <refpurpose>Generator for automatically discovering and mounting root, <filename>/home/</filename>,
+    <filename>/srv/</filename>, <filename>/var/</filename> and <filename>/var/tmp/</filename> partitions, as
+    well as discovering and enabling swap partitions, based on GPT partition type GUIDs</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <para><filename>/usr/lib/systemd/system-generators/systemd-gpt-auto-generator</filename></para>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><filename>systemd-gpt-auto-generator</filename> is a unit generator that automatically discovers
+    root, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>,
+    <filename>/var/tmp/</filename>, the EFI System Partition, the Extended Boot Loader Partition and swap
+    partitions and creates mount and swap units for them, based on the partition type GUIDs of GUID partition
+    tables (GPT), see <ulink url="https://uefi.org/specifications">UEFI Specification</ulink>, chapter 5. It
+    implements the <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
+    Specification</ulink>. Note that this generator has no effect on non-GPT systems, and on specific mount
+    points that are directories already containing files. Also, on systems where the units are explicitly
+    configured (for example, listed in <citerefentry
+    project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>), the
+    units this generator creates are overridden, but additional implicit dependencies might be
+    created.</para>
+
+    <para>This generator will only look for the root partition on the same physical disk where the EFI System
+    Partition (ESP) is located. Note that support from the boot loader is required: the EFI variable
+    <varname>LoaderDevicePartUUID</varname> of the <constant>4a67b082-0a4c-41cf-b6c7-440b29bb8c4f</constant>
+    vendor UUID is used to determine from which partition, and hence the disk from which the system was
+    booted. If the boot loader does not set this variable, this generator will not be able to autodetect the
+    root partition. See the <ulink url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader
+    Interface</ulink> for details.</para>
+
+    <para>Similarly, this generator will only look for the other partitions on the same physical disk as the
+    root partition. In this case, boot loader support is not required. These partitions will not be searched
+    for on systems where the root file system is distributed on multiple disks, for example via btrfs RAID.
+    </para>
+
+    <para><filename>systemd-gpt-auto-generator</filename> is useful for centralizing file system
+    configuration in the partition table and making configuration in <filename>/etc/fstab</filename> or on
+    the kernel command line unnecessary.</para>
+
+    <para>This generator looks for the partitions based on their
+    partition type GUID. The following partition type GUIDs are
+    identified:</para>
+
+    <table>
+      <title>Partition Type GUIDs</title>
+      <tgroup cols='3' align='left' colsep='1' rowsep='1'>
+        <colspec colname="guid" />
+        <colspec colname="name" />
+        <colspec colname="where" />
+        <colspec colname="explanation" />
+        <thead>
+          <row>
+            <entry>Partition Type GUID</entry>
+            <entry>Name</entry>
+            <entry>Mount Point</entry>
+            <entry>Explanation</entry>
+          </row>
+        </thead>
+        <tbody>
+          <row>
+            <entry><constant>SD_GPT_ROOT_X86_64</constant> <constant>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</constant></entry>
+            <entry><filename>Root Partition (x86-64)</filename></entry>
+            <entry><filename>/</filename></entry>
+            <entry>The first partition with this type UUID, located on the same disk as the ESP, is used as the root file system <filename>/</filename> on AMD64 / 64-bit x86 systems.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_ROOT_ARM64</constant> <constant>b921b045-1df0-41c3-af44-4c6f280d3fae</constant></entry>
+            <entry><filename>Root Partition (64-bit ARM)</filename></entry>
+            <entry><filename>/</filename></entry>
+            <entry>The first partition with this type UUID, located on the same disk as the ESP, is used as the root file system <filename>/</filename> on AArch64 / 64-bit ARM systems.</entry>
+          </row>
+          <row>
+            <entry>
+              <constant>SD_GPT_ROOT_ALPHA</constant> <constant>SD_GPT_ROOT_ARC</constant> <constant>SD_GPT_ROOT_ARM</constant> <constant>SD_GPT_ROOT_ARM64</constant> <constant>SD_GPT_ROOT_IA64</constant> <constant>SD_GPT_ROOT_LOONGARCH64</constant> <constant>SD_GPT_ROOT_MIPS</constant> <constant>SD_GPT_ROOT_MIPS64</constant> <constant>SD_GPT_ROOT_MIPS_LE</constant> <constant>SD_GPT_ROOT_MIPS64_LE</constant> <constant>SD_GPT_ROOT_PARISC</constant> <constant>SD_GPT_ROOT_PPC</constant> <constant>SD_GPT_ROOT_PPC64</constant> <constant>SD_GPT_ROOT_PPC64_LE</constant> <constant>SD_GPT_ROOT_RISCV32</constant> <constant>SD_GPT_ROOT_RISCV64</constant> <constant>SD_GPT_ROOT_S390</constant> <constant>SD_GPT_ROOT_S390X</constant> <constant>SD_GPT_ROOT_TILEGX</constant> <constant>SD_GPT_ROOT_X86</constant> <constant>SD_GPT_ROOT_X86_64</constant> <constant>SD_GPT_USR_ALPHA</constant> <constant>SD_GPT_USR_ARC</constant> <constant>SD_GPT_USR_ARM</constant> <constant>SD_GPT_USR_IA64</constant> <constant>SD_GPT_USR_LOONGARCH64</constant> <constant>SD_GPT_USR_MIPS_LE</constant> <constant>SD_GPT_USR_MIPS64_LE</constant> <constant>SD_GPT_USR_PARISC</constant> <constant>SD_GPT_USR_PPC</constant> <constant>SD_GPT_USR_PPC64</constant> <constant>SD_GPT_USR_PPC64_LE</constant> <constant>SD_GPT_USR_RISCV32</constant> <constant>SD_GPT_USR_RISCV64</constant> <constant>SD_GPT_USR_S390</constant> <constant>SD_GPT_USR_S390X</constant> <constant>SD_GPT_USR_TILEGX</constant> <constant>SD_GPT_USR_X86</constant>
+            </entry>
+            <entry>root partitions for other architectures</entry>
+            <entry><filename>/</filename></entry>
+            <entry>The first partition with the type UUID matching the architecture, located on the same disk as the ESP, is used as the root file system <filename>/</filename>. For the full list and constant values, see <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions Specification</ulink>.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_HOME</constant> <constant>933ac7e1-2eb4-4f13-b844-0e14e2aef915</constant></entry>
+            <entry>Home Partition</entry>
+            <entry><filename>/home/</filename></entry>
+            <entry>The first partition with this type UUID on the same disk as the ESP is mounted to <filename>/home/</filename>.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_SRV</constant> <constant>3b8f8425-20e0-4f3b-907f-1a25a76f98e8</constant></entry>
+            <entry>Server Data Partition</entry>
+            <entry><filename>/srv/</filename></entry>
+            <entry>The first partition with this type UUID on the same disk as the ESP is mounted to <filename>/srv/</filename>.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_VAR</constant> <constant>4d21b016-b534-45c2-a9fb-5c16e091fd2d</constant></entry>
+            <entry>Variable Data Partition</entry>
+            <entry><filename>/var/</filename></entry>
+            <entry>The first partition with this type UUID on the same disk as the ESP is mounted to <filename>/var/</filename> — under the condition its partition UUID matches the first 128 bit of the HMAC-SHA256 of the GPT type uuid of this partition keyed by the machine ID of the installation stored in <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_TMP</constant> <constant>7ec6f557-3bc5-4aca-b293-16ef5df639d1</constant></entry>
+            <entry>Temporary Data Partition</entry>
+            <entry><filename>/var/tmp/</filename></entry>
+            <entry>The first partition with this type UUID on the same disk as the ESP is mounted to <filename>/var/tmp/</filename>.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_SWAP</constant> <constant>0657fd6d-a4ab-43c4-84e5-0933c84b4f4f</constant></entry>
+            <entry>Swap</entry>
+            <entry>n/a</entry>
+            <entry>All partitions with this type UUID on the same disk as the ESP are used as swap.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_ESP</constant> <constant>c12a7328-f81f-11d2-ba4b-00a0c93ec93b</constant></entry>
+            <entry>EFI System Partition (ESP)</entry>
+            <entry><filename>/efi/</filename> or <filename>/boot/</filename></entry>
+            <entry>The first partition with this type UUID located on the same disk as the root partition is mounted to <filename>/boot/</filename> or <filename>/efi/</filename>, see below.</entry>
+          </row>
+          <row>
+            <entry><constant>SD_GPT_XBOOTLDR</constant> <constant>bc13c2ff-59e6-4262-a352-b275fd6f7172</constant></entry>
+            <entry>Extended Boot Loader Partition</entry>
+            <entry><filename>/boot/</filename></entry>
+            <entry>The first partition with this type UUID located on the same disk as the root partition is mounted to <filename>/boot/</filename>, see below.</entry>
+          </row>
+        </tbody>
+      </tgroup>
+    </table>
+
+    <para>This generator understands the following attribute flags for partitions:</para>
+
+    <table>
+      <title>Partition Attribute Flags</title>
+      <tgroup cols='3' align='left' colsep='1' rowsep='1'>
+        <colspec colname="flag" />
+        <colspec colname="where" />
+        <colspec colname="explanation" />
+        <thead>
+          <row>
+            <entry>Flag</entry>
+            <entry>Applicable to</entry>
+            <entry>Explanation</entry>
+          </row>
+        </thead>
+        <tbody>
+          <row>
+            <entry><constant>SD_GPT_FLAG_READ_ONLY</constant> <constant>0x1000000000000000</constant></entry>
+            <entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>, <filename>/var/tmp/</filename>, Extended Boot Loader Partition</entry>
+            <entry>Partition is mounted read-only</entry>
+          </row>
+
+          <row>
+            <entry><constant>SD_GPT_FLAG_NO_AUTO</constant> <constant>0x8000000000000000</constant></entry>
+            <entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename>, <filename>/var/tmp/</filename>, Extended Boot Loader Partition</entry>
+            <entry>Partition is not mounted automatically</entry>
+          </row>
+
+          <row>
+            <entry><constant>SD_GPT_FLAG_NO_BLOCK_IO_PROTOCOL</constant> <constant>0x0000000000000002</constant></entry>
+            <entry>EFI System Partition (ESP)</entry>
+            <entry>Partition is not mounted automatically</entry>
+          </row>
+        </tbody>
+      </tgroup>
+    </table>
+
+    <para>The <filename>/home/</filename>, <filename>/srv/</filename>, <filename>/var/</filename> and
+    <filename>/var/tmp/</filename> partitions may be encrypted in LUKS format. In this case, a device mapper
+    device is set up under the names <filename>/dev/mapper/home</filename>,
+    <filename>/dev/mapper/srv</filename>, <filename>/dev/mapper/var</filename> and
+    <filename>/dev/mapper/tmp</filename>. Note that this might create conflicts if the same partition is
+    listed in <filename>/etc/crypttab</filename> with a different device mapper device name.</para>
+
+    <para>When systemd is running in the initrd the <filename>/</filename> partition may be encrypted in LUKS
+      format as well. In this case, a device mapper device is set up under the name <filename>/dev/mapper/root</filename>,
+      and a <filename>sysroot.mount</filename> is set up that mounts the device under <filename>/sysroot</filename>.
+      For more information, see <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+    </para>
+
+    <para>The root partition can be specified by symlinking <filename>/run/systemd/volatile-root</filename>
+    to <filename>/dev/block/$major:$minor</filename>. This is especially useful if the root mount has been
+    replaced by some form of volatile file system (overlayfs).
+    </para>
+
+    <para>Mount and automount units for the EFI System Partition (ESP) are generated on EFI systems. The ESP
+    is mounted to <filename>/boot/</filename> (except if an Extended Boot Loader partition exists, see
+    below), unless a mount point directory <filename>/efi/</filename> exists, in which case it is mounted
+    there. Since this generator creates an automount unit, the mount will only be activated on-demand, when
+    accessed. On systems where <filename>/boot/</filename> (or <filename>/efi/</filename> if it exists) is an
+    explicitly configured mount (for example, listed in <citerefentry
+    project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>) or where
+    the <filename>/boot/</filename> (or <filename>/efi/</filename>) mount point is non-empty, no mount units
+    are generated.</para>
+
+    <para>If the disk contains an Extended Boot Loader partition, as defined in the <ulink
+    url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification</ulink>, it is made
+    available at <filename>/boot/</filename> (by means of an automount point, similar to the ESP, see
+    above). If both an EFI System Partition and an Extended Boot Loader partition exist the latter is
+    preferably mounted to <filename>/boot/</filename>. Make sure to create both <filename>/efi/</filename>
+    and <filename>/boot/</filename> to ensure both partitions are mounted.</para>
+
+    <para>When using this generator in conjunction with btrfs file
+    systems, make sure to set the correct default subvolumes on them,
+    using <command>btrfs subvolume set-default</command>.</para>
+
+    <para><filename>systemd-gpt-auto-generator</filename> implements
+    <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Kernel Command Line</title>
+
+    <para><filename>systemd-gpt-auto-generator</filename> understands the following kernel command line
+    parameters:</para>
+
+    <variablelist class='kernel-commandline-options'>
+
+      <varlistentry>
+        <term><varname>systemd.gpt_auto</varname></term>
+        <term><varname>rd.systemd.gpt_auto</varname></term>
+
+        <listitem><para>Those options take an optional boolean argument, and default to yes.
+        The generator is enabled by default, and a false value may be used to disable it
+        (e.g. <literal>systemd.gpt_auto=0</literal>).
+        </para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>root=</varname></term>
+
+        <listitem><para>When used with the special value <literal>gpt-auto</literal>, automatic discovery of
+        the root partition based on the GPT partition type is enabled.  Any other value disables this
+        generator.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>rw</varname></term>
+        <term><varname>ro</varname></term>
+
+        <listitem><para>Mount the root partition read-write or read-only <emphasis>initially</emphasis>.</para>
+
+        <para>Note that unlike most kernel command line options these settings do not override configuration
+        in the file system, and the file system may be remounted later. See
+        <citerefentry><refentrytitle>systemd-remount-fs.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+        </para></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>See Also</title>
+    <para>
+      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>