man/systemd-gpt-auto-generator.xml

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   9   Copyright 2013 Lennart Poettering
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  24 <refentry id="systemd-gpt-auto-generator">
  25
  26   <refentryinfo>
  27     <title>systemd-gpt-auto-generator</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Lennart</firstname>
  34         <surname>Poettering</surname>
  35         <email>lennart@poettering.net</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>systemd-gpt-auto-generator</refentrytitle>
  42     <manvolnum>8</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>systemd-gpt-auto-generator</refname>
  47     <refpurpose>Generator for automatically discovering
  48     and mounting root, <filename>/home</filename> and
  49     <filename>/srv</filename> partitions, as well as
  50     discovering and enabling swap partitions, based on GPT
  51     partition type GUIDs.</refpurpose>
  52   </refnamediv>
  53
  54   <refsynopsisdiv>
  55     <para><filename>/usr/lib/systemd/system-generators/systemd-gpt-auto-generator</filename></para>
  56   </refsynopsisdiv>
  57
  58   <refsect1>
  59     <title>Description</title>
  60
  61     <para><filename>systemd-gpt-auto-generator</filename> is a unit
  62     generator that automatically discovers root,
  63     <filename>/home</filename>, <filename>/srv</filename> and swap
  64     partitions and creates mount and swap units for them, based on the
  65     partition type GUIDs of GUID partition tables (GPT),
  66     see <ulink url="http://www.uefi.org/specifications">UEFI Specification</ulink>, chapter 5.
  67     It implements the <ulink
  68     url="https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">Discoverable
  69     Partitions Specification</ulink>. Note that this generator has no
  70     effect on non-GPT systems, or where the directories under the
  71     mount points are already non-empty. Also, on systems where the
  72     units are explicitly configured (for example, listed in
  73     <citerefentry
  74     project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
  75     the units this generator creates are overridden, but additional
  76     implicit dependencies might be created.</para>
  77
  78     <para>This generator will only look for root partitions on the
  79     same physical disk the EFI System Partition (ESP) is located on.
  80     It will only look for the other partitions on the same physical
  81     disk the root file system is located on. These partitions will not
  82     be searched for on systems where the root file system is distributed
  83     on multiple disks, for example via btrfs RAID.</para>
  84
  85     <para><filename>systemd-gpt-auto-generator</filename> is useful
  86     for centralizing file system configuration in the partition table
  87     and making configuration in <filename>/etc/fstab</filename> unnecessary.
  88     </para>
  89
  90     <para>This generator looks for the partitions based on their
  91     partition type GUID. The following partition type GUIDs are
  92     identified:</para>
  93
  94     <table>
  95       <title>Partition Type GUIDs</title>
  96       <tgroup cols='3' align='left' colsep='1' rowsep='1'>
  97         <colspec colname="guid" />
  98         <colspec colname="name" />
  99         <colspec colname="explanation" />
 100         <thead>
 101           <row>
 102             <entry>Partition Type GUID</entry>
 103             <entry>Name</entry>
 104             <entry>Explanation</entry>
 105           </row>
 106         </thead>
 107         <tbody>
 108           <row>
 109             <entry>44479540-f297-41b2-9af7-d131d5f0458a</entry>
 110             <entry><filename>Root Partition (x86)</filename></entry>
 111             <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>
 112           </row>
 113           <row>
 114             <entry>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</entry>
 115             <entry><filename>Root Partition (x86-64)</filename></entry>
 116             <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>
 117           </row>
 118           <row>
 119             <entry>69dad710-2ce4-4e3c-b16c-21a1d49abed3</entry>
 120             <entry><filename>Root Partition (32-bit ARM)</filename></entry>
 121             <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>
 122           </row>
 123           <row>
 124             <entry>b921b045-1df0-41c3-af44-4c6f280d3fae</entry>
 125             <entry><filename>Root Partition (64-bit ARM)</filename></entry>
 126             <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>
 127           </row>
 128           <row>
 129             <entry>993d8d3d-f80e-4225-855a-9daf8ed7ea97</entry>
 130             <entry><filename>Root Partition (Itanium/IA-64)</filename></entry>
 131             <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>
 132           </row>
 133           <row>
 134             <entry>933ac7e1-2eb4-4f13-b844-0e14e2aef915</entry>
 135             <entry>Home Partition</entry>
 136             <entry>The first home partition on the disk the root partition is located on is mounted to <filename>/home</filename>.</entry>
 137           </row>
 138           <row>
 139             <entry>3b8f8425-20e0-4f3b-907f-1a25a76f98e8</entry>
 140             <entry>Server Data Partition</entry>
 141             <entry>The first server data partition on the disk the root partition is located on is mounted to <filename>/srv</filename>.</entry>
 142           </row>
 143           <row>
 144             <entry>0657fd6d-a4ab-43c4-84e5-0933c84b4f4f</entry>
 145             <entry>Swap</entry>
 146             <entry>All swap partitions located on the disk the root partition is located on are enabled.</entry>
 147           </row>
 148           <row>
 149             <entry>c12a7328-f81f-11d2-ba4b-00a0c93ec93b</entry>
 150             <entry>EFI System Partition (ESP)</entry>
 151             <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>
 152           </row>
 153         </tbody>
 154       </tgroup>
 155     </table>
 156
 157     <para>This generator understands the following attribute flags for partitions:</para>
 158
 159     <table>
 160       <title>Partition Attributes</title>
 161       <tgroup cols='4' align='left' colsep='1' rowsep='1'>
 162         <colspec colname="attribute" />
 163         <colspec colname="value" />
 164         <colspec colname="where" />
 165         <colspec colname="explanation" />
 166         <thead>
 167           <row>
 168             <entry>Name</entry>
 169             <entry>Value</entry>
 170             <entry>Applicable to</entry>
 171             <entry>Explanation</entry>
 172           </row>
 173         </thead>
 174         <tbody>
 175           <row>
 176             <entry><constant>GPT_FLAG_READ_ONLY</constant></entry>
 177             <entry>0x1000000000000000</entry>
 178             <entry><filename>/</filename>, <filename>/srv</filename>, <filename>/home</filename></entry>
 179             <entry>Partition is mounted read-only</entry>
 180           </row>
 181
 182           <row>
 183             <entry><constant>GPT_FLAG_NO_AUTO</constant></entry>
 184             <entry>0x8000000000000000</entry>
 185             <entry><filename>/</filename>, <filename>/srv</filename>, <filename>/home</filename></entry>
 186             <entry>Partition is not mounted automatically</entry>
 187           </row>
 188
 189           <row>
 190             <entry><constant>GPT_FLAG_NO_BLOCK_IO_PROTOCOL</constant></entry>
 191             <entry>0x0000000000000002</entry>
 192             <entry>ESP</entry>
 193             <entry>Partition is not mounted automatically</entry>
 194           </row>
 195         </tbody>
 196       </tgroup>
 197     </table>
 198
 199     <para>The <filename>/home</filename> and <filename>/srv</filename>
 200     partitions may be encrypted in LUKS format. In this case, a device
 201     mapper device is set up under the names
 202     <filename>/dev/mapper/home</filename> and
 203     <filename>/dev/mapper/srv</filename>. Note that this might create
 204     conflicts if the same partition is listed in
 205     <filename>/etc/crypttab</filename> with a different device mapper
 206     device name.</para>
 207
 208     <para>Mount and automount units for the EFI System Partition (ESP) are generated on EFI systems. The ESP is mounted
 209     to <filename>/boot</filename>, unless a mount point directory <filename>/efi</filename> exists, in which case it is
 210     mounted there. Since this generator creates an automount unit, the mount will only be activated on-demand, when
 211     accessed. On systems where <filename>/boot</filename> (or <filename>/efi</filename> if it exists) is an explicitly
 212     configured mount (for example, listed in <citerefentry
 213     project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>) or where the
 214     <filename>/boot</filename> (or <filename>/efi</filename>) mount point is non-empty, no mount units are
 215     generated.</para>
 216
 217     <para>When using this generator in conjunction with btrfs file
 218     systems, make sure to set the correct default subvolumes on them,
 219     using <command>btrfs subvolume set-default</command>.</para>
 220
 221     <para><filename>systemd-gpt-auto-generator</filename> implements
 222     <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 223   </refsect1>
 224
 225   <refsect1>
 226     <title>See Also</title>
 227     <para>
 228       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 229       <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 230       <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 231       <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 232       <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 233       <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 234       <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 235       <citerefentry project='man-pages'><refentrytitle>btrfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 236     </para>
 237   </refsect1>
 238
 239 </refentry>