1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
|
<?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+ -->
<refentry id="systemd-gpt-auto-generator">
<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> and
<filename>/srv</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>, 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="http://www.uefi.org/specifications">UEFI Specification</ulink>, chapter 5. It implements the <ulink
url="https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/">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 root partitions on the
same physical disk the EFI System Partition (ESP) is located on.
It will only look for the other partitions on the same physical
disk the root file system is located on. 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> 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>44479540-f297-41b2-9af7-d131d5f0458a</entry>
<entry><filename>Root Partition (x86)</filename></entry>
<entry><filename>/</filename></entry>
<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>
</row>
<row>
<entry>4f68bce3-e8cd-4db1-96e7-fbcaf984b709</entry>
<entry><filename>Root Partition (x86-64)</filename></entry>
<entry><filename>/</filename></entry>
<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>
</row>
<row>
<entry>69dad710-2ce4-4e3c-b16c-21a1d49abed3</entry>
<entry><filename>Root Partition (32-bit ARM)</filename></entry>
<entry><filename>/</filename></entry>
<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>
</row>
<row>
<entry>b921b045-1df0-41c3-af44-4c6f280d3fae</entry>
<entry><filename>Root Partition (64-bit ARM)</filename></entry>
<entry><filename>/</filename></entry>
<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>
</row>
<row>
<entry>993d8d3d-f80e-4225-855a-9daf8ed7ea97</entry>
<entry><filename>Root Partition (Itanium/IA-64)</filename></entry>
<entry><filename>/</filename></entry>
<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>
</row>
<row>
<entry>933ac7e1-2eb4-4f13-b844-0e14e2aef915</entry>
<entry>Home Partition</entry>
<entry><filename>/home/</filename></entry>
<entry>The first home partition on the disk the root partition is located on is mounted to <filename>/home</filename>.</entry>
</row>
<row>
<entry>3b8f8425-20e0-4f3b-907f-1a25a76f98e8</entry>
<entry>Server Data Partition</entry>
<entry><filename>/srv/</filename></entry>
<entry>The first server data partition on the disk the root partition is located on is mounted to <filename>/srv</filename>.</entry>
</row>
<row>
<entry>0657fd6d-a4ab-43c4-84e5-0933c84b4f4f</entry>
<entry>Swap</entry>
<entry>n/a</entry>
<entry>All swap partitions located on the disk the root partition is located on are enabled.</entry>
</row>
<row>
<entry>c12a7328-f81f-11d2-ba4b-00a0c93ec93b</entry>
<entry>EFI System Partition (ESP)</entry>
<entry><filename>/efi/</filename> or <filename>/boot/</filename></entry>
<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>
</row>
<row>
<entry>bc13c2ff-59e6-4262-a352-b275fd6f7172</entry>
<entry>Extended Boot Loader Partition</entry>
<entry><filename>/boot/</filename></entry>
<entry>The first Extended Boot Loader 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 Attributes</title>
<tgroup cols='4' align='left' colsep='1' rowsep='1'>
<colspec colname="attribute" />
<colspec colname="value" />
<colspec colname="where" />
<colspec colname="explanation" />
<thead>
<row>
<entry>Name</entry>
<entry>Value</entry>
<entry>Applicable to</entry>
<entry>Explanation</entry>
</row>
</thead>
<tbody>
<row>
<entry><constant>GPT_FLAG_READ_ONLY</constant></entry>
<entry>0x1000000000000000</entry>
<entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, Extended Boot Loader Partition</entry>
<entry>Partition is mounted read-only</entry>
</row>
<row>
<entry><constant>GPT_FLAG_NO_AUTO</constant></entry>
<entry>0x8000000000000000</entry>
<entry><filename>/</filename>, <filename>/home/</filename>, <filename>/srv/</filename>, Extended Boot Loader Partition</entry>
<entry>Partition is not mounted automatically</entry>
</row>
<row>
<entry><constant>GPT_FLAG_NO_BLOCK_IO_PROTOCOL</constant></entry>
<entry>0x0000000000000002</entry>
<entry>EFI System Partition (ESP)</entry>
<entry>Partition is not mounted automatically</entry>
</row>
</tbody>
</tgroup>
</table>
<para>The <filename>/home/</filename> and <filename>/srv/</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> and <filename>/dev/mapper/srv</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>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 negative value may be used to disable it.
</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 parition 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 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>
|
