man/systemd-gpt-auto-generator.xml

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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!--
   5   SPDX-License-Identifier: LGPL-2.1+
   6
   7   This file is part of systemd.
   8
   9   Copyright 2013 Lennart Poettering
  10 -->
  11 <refentry id="systemd-gpt-auto-generator">
  12
  13   <refentryinfo>
  14     <title>systemd-gpt-auto-generator</title>
  15     <productname>systemd</productname>
  16
  17     <authorgroup>
  18       <author>
  19         <contrib>Developer</contrib>
  20         <firstname>Lennart</firstname>
  21         <surname>Poettering</surname>
  22         <email>lennart@poettering.net</email>
  23       </author>
  24     </authorgroup>
  25   </refentryinfo>
  26
  27   <refmeta>
  28     <refentrytitle>systemd-gpt-auto-generator</refentrytitle>
  29     <manvolnum>8</manvolnum>
  30   </refmeta>
  31
  32   <refnamediv>
  33     <refname>systemd-gpt-auto-generator</refname>
  34     <refpurpose>Generator for automatically discovering
  35     and mounting root, <filename>/home</filename> and
  36     <filename>/srv</filename> partitions, as well as
  37     discovering and enabling swap partitions, based on GPT
  38     partition type GUIDs.</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <para><filename>/usr/lib/systemd/system-generators/systemd-gpt-auto-generator</filename></para>
  43   </refsynopsisdiv>
  44
  45   <refsect1>
  46     <title>Description</title>
  47
  48     <para><filename>systemd-gpt-auto-generator</filename> is a unit
  49     generator that automatically discovers root,
  50     <filename>/home</filename>, <filename>/srv</filename> and swap
  51     partitions and creates mount and swap units for them, based on the
  52     partition type GUIDs of GUID partition tables (GPT),
  53     see <ulink url="http://www.uefi.org/specifications">UEFI Specification</ulink>, chapter 5.
  54     It implements the <ulink
  55     url="https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
  56     Partitions Specification</ulink>. Note that this generator has no
  57     effect on non-GPT systems, or where the directories under the
  58     mount points are already non-empty. Also, on systems where the
  59     units are explicitly configured (for example, listed in
  60     <citerefentry
  61     project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
  62     the units this generator creates are overridden, but additional
  63     implicit dependencies might be created.</para>
  64
  65     <para>This generator will only look for root partitions on the
  66     same physical disk the EFI System Partition (ESP) is located on.
  67     It will only look for the other partitions on the same physical
  68     disk the root file system is located on. These partitions will not
  69     be searched for on systems where the root file system is distributed
  70     on multiple disks, for example via btrfs RAID.</para>
  71
  72     <para><filename>systemd-gpt-auto-generator</filename> is useful
  73     for centralizing file system configuration in the partition table
  74     and making configuration in <filename>/etc/fstab</filename> unnecessary.
  75     </para>
  76
  77     <para>This generator looks for the partitions based on their
  78     partition type GUID. The following partition type GUIDs are
  79     identified:</para>
  80
  81     <table>
  82       <title>Partition Type GUIDs</title>
  83       <tgroup cols='3' align='left' colsep='1' rowsep='1'>
  84         <colspec colname="guid" />
  85         <colspec colname="name" />
  86         <colspec colname="explanation" />
  87         <thead>
  88           <row>
  89             <entry>Partition Type GUID</entry>
  90             <entry>Name</entry>
  91             <entry>Explanation</entry>
  92           </row>
  93         </thead>
  94         <tbody>
  95           <row>
  96             <entry>44479540-f297-41b2-9af7-d131d5f0458a</entry>
  97             <entry><filename>Root Partition (x86)</filename></entry>
  98             <entry>On 32-bit x86 systems, the first x86 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
  99           </row>
 100           <row>
 101             <entry>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</entry>
 102             <entry><filename>Root Partition (x86-64)</filename></entry>
 103             <entry>On 64-bit x86 systems, the first x86-64 root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
 104           </row>
 105           <row>
 106             <entry>69dad710-2ce4-4e3c-b16c-21a1d49abed3</entry>
 107             <entry><filename>Root Partition (32-bit ARM)</filename></entry>
 108             <entry>On 32-bit ARM systems, the first ARM root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
 109           </row>
 110           <row>
 111             <entry>b921b045-1df0-41c3-af44-4c6f280d3fae</entry>
 112             <entry><filename>Root Partition (64-bit ARM)</filename></entry>
 113             <entry>On 64-bit ARM systems, the first ARM root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
 114           </row>
 115           <row>
 116             <entry>993d8d3d-f80e-4225-855a-9daf8ed7ea97</entry>
 117             <entry><filename>Root Partition (Itanium/IA-64)</filename></entry>
 118             <entry>On Itanium systems, the first Itanium root partition on the disk the EFI ESP is located on is mounted to the root directory <filename>/</filename>.</entry>
 119           </row>
 120           <row>
 121             <entry>933ac7e1-2eb4-4f13-b844-0e14e2aef915</entry>
 122             <entry>Home Partition</entry>
 123             <entry>The first home partition on the disk the root partition is located on is mounted to <filename>/home</filename>.</entry>
 124           </row>
 125           <row>
 126             <entry>3b8f8425-20e0-4f3b-907f-1a25a76f98e8</entry>
 127             <entry>Server Data Partition</entry>
 128             <entry>The first server data partition on the disk the root partition is located on is mounted to <filename>/srv</filename>.</entry>
 129           </row>
 130           <row>
 131             <entry>0657fd6d-a4ab-43c4-84e5-0933c84b4f4f</entry>
 132             <entry>Swap</entry>
 133             <entry>All swap partitions located on the disk the root partition is located on are enabled.</entry>
 134           </row>
 135           <row>
 136             <entry>c12a7328-f81f-11d2-ba4b-00a0c93ec93b</entry>
 137             <entry>EFI System Partition (ESP)</entry>
 138             <entry>The first ESP located on the disk the root partition is located on is mounted to <filename>/boot</filename> or <filename>/efi</filename>, see below.</entry>
 139           </row>
 140         </tbody>
 141       </tgroup>
 142     </table>
 143
 144     <para>This generator understands the following attribute flags for partitions:</para>
 145
 146     <table>
 147       <title>Partition Attributes</title>
 148       <tgroup cols='4' align='left' colsep='1' rowsep='1'>
 149         <colspec colname="attribute" />
 150         <colspec colname="value" />
 151         <colspec colname="where" />
 152         <colspec colname="explanation" />
 153         <thead>
 154           <row>
 155             <entry>Name</entry>
 156             <entry>Value</entry>
 157             <entry>Applicable to</entry>
 158             <entry>Explanation</entry>
 159           </row>
 160         </thead>
 161         <tbody>
 162           <row>
 163             <entry><constant>GPT_FLAG_READ_ONLY</constant></entry>
 164             <entry>0x1000000000000000</entry>
 165             <entry><filename>/</filename>, <filename>/srv</filename>, <filename>/home</filename></entry>
 166             <entry>Partition is mounted read-only</entry>
 167           </row>
 168
 169           <row>
 170             <entry><constant>GPT_FLAG_NO_AUTO</constant></entry>
 171             <entry>0x8000000000000000</entry>
 172             <entry><filename>/</filename>, <filename>/srv</filename>, <filename>/home</filename></entry>
 173             <entry>Partition is not mounted automatically</entry>
 174           </row>
 175
 176           <row>
 177             <entry><constant>GPT_FLAG_NO_BLOCK_IO_PROTOCOL</constant></entry>
 178             <entry>0x0000000000000002</entry>
 179             <entry>ESP</entry>
 180             <entry>Partition is not mounted automatically</entry>
 181           </row>
 182         </tbody>
 183       </tgroup>
 184     </table>
 185
 186     <para>The <filename>/home</filename> and <filename>/srv</filename>
 187     partitions may be encrypted in LUKS format. In this case, a device
 188     mapper device is set up under the names
 189     <filename>/dev/mapper/home</filename> and
 190     <filename>/dev/mapper/srv</filename>. Note that this might create
 191     conflicts if the same partition is listed in
 192     <filename>/etc/crypttab</filename> with a different device mapper
 193     device name.</para>
 194
 195     <para>Mount and automount units for the EFI System Partition (ESP) are generated on EFI systems. The ESP is mounted
 196     to <filename>/boot</filename>, unless a mount point directory <filename>/efi</filename> exists, in which case it is
 197     mounted there. Since this generator creates an automount unit, the mount will only be activated on-demand, when
 198     accessed. On systems where <filename>/boot</filename> (or <filename>/efi</filename> if it exists) is an explicitly
 199     configured mount (for example, listed in <citerefentry
 200     project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>) or where the
 201     <filename>/boot</filename> (or <filename>/efi</filename>) mount point is non-empty, no mount units are
 202     generated.</para>
 203
 204     <para>When using this generator in conjunction with btrfs file
 205     systems, make sure to set the correct default subvolumes on them,
 206     using <command>btrfs subvolume set-default</command>.</para>
 207
 208     <para><filename>systemd-gpt-auto-generator</filename> implements
 209     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 210   </refsect1>
 211
 212   <refsect1>
 213     <title>See Also</title>
 214     <para>
 215       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 216       <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 217       <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 218       <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 219       <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 220       <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 221       <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 222       <citerefentry project='man-pages'><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 223     </para>
 224   </refsect1>
 225
 226 </refentry>