man/systemd-gpt-auto-generator.xml

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