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f37d3835 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
f37d3835 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
f37d3835 | 5 | |
ba38a24d | 6 | <refentry id="systemd-boot" conditional='HAVE_GNU_EFI' |
f37d3835 ZJS |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> |
8 | <refentryinfo> | |
70c8db75 | 9 | <title>systemd-boot</title> |
f37d3835 | 10 | <productname>systemd</productname> |
f37d3835 ZJS |
11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
70c8db75 | 14 | <refentrytitle>systemd-boot</refentrytitle> |
f37d3835 ZJS |
15 | <manvolnum>7</manvolnum> |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
70c8db75 | 19 | <refname>systemd-boot</refname> |
f37d3835 ZJS |
20 | <refname>sd-boot</refname> |
21 | <refpurpose>A simple UEFI boot manager</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsect1> | |
25 | <title>Description</title> | |
26 | ||
c5fcaed8 | 27 | <para><command>systemd-boot</command> (short: <command>sd-boot</command>) is a simple UEFI boot |
b8cdb662 | 28 | manager. It provides a textual menu to select the entry to boot and an editor for the kernel command |
c5fcaed8 | 29 | line. <command>systemd-boot</command> supports systems with UEFI firmware only.</para> |
53ddb667 | 30 | |
39867bb9 LP |
31 | <para><command>systemd-boot</command> loads boot entry information from the EFI system partition (ESP), |
32 | usually mounted at <filename>/efi/</filename>, <filename>/boot/</filename>, or | |
cafa9d87 LP |
33 | <filename>/boot/efi/</filename> during OS runtime, as well as from the Extended Boot Loader partition |
34 | (XBOOTLDR) if it exists (usually mounted to <filename>/boot/</filename>). Configuration file fragments, | |
35 | kernels, initrds and other EFI images to boot generally need to reside on the ESP or the Extended Boot | |
36 | Loader partition. Linux kernels must be built with <option>CONFIG_EFI_STUB</option> to be able to be | |
37 | directly executed as an EFI image. During boot <command>systemd-boot</command> automatically assembles a | |
38 | list of boot entries from the following sources:</para> | |
53ddb667 LP |
39 | |
40 | <itemizedlist> | |
41 | <listitem><para>Boot entries defined with <ulink | |
db811444 | 42 | url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink> Type #1 |
a0aa3838 ZJS |
43 | description files located in <filename>/loader/entries/</filename> on the ESP and the Extended Boot |
44 | Loader Partition. These usually describe Linux kernel images with associated initrd images, but | |
45 | alternatively may also describe other arbitrary EFI executables.</para></listitem> | |
53ddb667 | 46 | |
db811444 | 47 | <listitem><para>Unified kernel images, <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot |
a0aa3838 ZJS |
48 | Loader Specification</ulink> Type #2, which are executable EFI binaries in |
49 | <filename>/EFI/Linux/</filename> on the ESP and the Extended Boot Loader Partition.</para></listitem> | |
53ddb667 | 50 | |
a0aa3838 | 51 | <listitem><para>The Microsoft Windows EFI boot manager, if installed.</para></listitem> |
53ddb667 | 52 | |
a0aa3838 | 53 | <listitem><para>The Apple macOS boot manager, if installed.</para></listitem> |
53ddb667 | 54 | |
a0aa3838 | 55 | <listitem><para>The EFI Shell binary, if installed.</para></listitem> |
53ddb667 | 56 | |
a0aa3838 | 57 | <listitem><para>A reboot into the UEFI firmware setup option, if supported by the firmware.</para></listitem> |
e6b0cfad | 58 | |
8b9f0921 | 59 | <listitem><para>Secure Boot variables enrollment if the UEFI firmware is in setup-mode and files are provided |
e6b0cfad | 60 | on the ESP.</para></listitem> |
53ddb667 LP |
61 | </itemizedlist> |
62 | ||
39867bb9 LP |
63 | <para><command>systemd-boot</command> supports the following features:</para> |
64 | ||
65 | <itemizedlist> | |
66 | <listitem><para>Basic boot manager configuration changes (such as timeout | |
67 | configuration, default boot entry selection, …) may be made directly from the boot loader UI at | |
68 | boot-time, as well as during system runtime with EFI variables.</para></listitem> | |
69 | ||
70 | <listitem><para>The boot manager integrates with the <command>systemctl</command> command to implement | |
71 | features such as <command>systemctl reboot --boot-loader-entry=…</command> (for rebooting into a | |
72 | specific boot menu entry, i.e. "reboot into Windows") and <command>systemctl reboot | |
73 | --boot-loader-menu=…</command> (for rebooting into the boot loader menu), by implementing the <ulink | |
74 | url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader Interface</ulink>. See | |
75 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> for | |
76 | details.</para></listitem> | |
77 | ||
250db1bf | 78 | <listitem><para>An EFI variable set by the boot loader informs the OS about the EFI System Partition used |
79 | during boot. This is then used to automatically mount the correct EFI System Partition to | |
39867bb9 LP |
80 | <filename>/efi/</filename> or <filename>/boot/</filename> during OS runtime. See |
81 | <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
82 | for details.</para></listitem> | |
83 | ||
84 | <listitem><para>The boot manager provides information about the boot time spent in UEFI firmware using | |
85 | the <ulink url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader Interface</ulink>. This | |
86 | information can be displayed using | |
87 | <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>. | |
88 | </para></listitem> | |
89 | ||
90 | <listitem><para>The boot manager implements boot counting and automatic fallback to older, working boot | |
91 | entries on failure. See <ulink url="https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT">Automatic Boot | |
92 | Assessment</ulink>.</para></listitem> | |
93 | ||
94 | <listitem><para>The boot manager optionally reads a random seed from the ESP partition, combines it | |
11fcfc53 | 95 | with a 'system token' stored in a persistent EFI variable and derives a random seed to use by the OS as |
e9dd6984 | 96 | entropy pool initialization, providing a full entropy pool during early boot.</para></listitem> |
e6b0cfad | 97 | |
8b9f0921 | 98 | <listitem><para>The boot manager allows for Secure Boot variables to be enrolled if the UEFI firmware is |
e6b0cfad | 99 | in setup-mode. Additionally, variables can be automatically enrolled if configured.</para></listitem> |
39867bb9 LP |
100 | </itemizedlist> |
101 | ||
102 | <para><citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
c5fcaed8 LP |
103 | may be used from a running system to locate the ESP and the Extended Boot Loader Partition, list |
104 | available entries, and install <command>systemd-boot</command> itself.</para> | |
53ddb667 | 105 | |
39867bb9 LP |
106 | <para><citerefentry><refentrytitle>kernel-install</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
107 | may be used to copy kernel images onto the ESP or the Extended Boot Loader Partition and to generate | |
108 | description files compliant with the Boot Loader | |
109 | Specification.</para> | |
3f9a615d LP |
110 | |
111 | <para><citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
112 | may be used as UEFI boot stub for executed kernels, which is useful to show graphical boot splashes | |
113 | before transitioning into the Linux world. It is also capable of automatically picking up auxiliary | |
114 | credential files (for boot parameterization) and system extension images, as companion files to the | |
115 | booted kernel images.</para> | |
f37d3835 ZJS |
116 | </refsect1> |
117 | ||
f37d3835 ZJS |
118 | <refsect1> |
119 | <title>Key bindings</title> | |
120 | <para>The following keys may be used in the boot menu:</para> | |
121 | ||
8a8e5666 JJ |
122 | <!-- Developer commands Q/v/Ctrl+l deliberately not advertised. --> |
123 | ||
f37d3835 ZJS |
124 | <variablelist> |
125 | <varlistentry> | |
8c073dde LP |
126 | <term><keycap>↑</keycap> (Up)</term> |
127 | <term><keycap>↓</keycap> (Down)</term> | |
128 | <term><keycap>j</keycap></term> | |
129 | <term><keycap>k</keycap></term> | |
130 | <term><keycap>PageUp</keycap></term> | |
131 | <term><keycap>PageDown</keycap></term> | |
132 | <term><keycap>Home</keycap></term> | |
133 | <term><keycap>End</keycap></term> | |
f37d3835 ZJS |
134 | <listitem><para>Navigate up/down in the entry list</para></listitem> |
135 | </varlistentry> | |
136 | ||
137 | <varlistentry> | |
8c073dde | 138 | <term><keycap>↵</keycap> (Enter)</term> |
904ebcb2 | 139 | <term><keycap>→</keycap> (Right)</term> |
f37d3835 ZJS |
140 | <listitem><para>Boot selected entry</para></listitem> |
141 | </varlistentry> | |
142 | ||
143 | <varlistentry> | |
8c073dde | 144 | <term><keycap>d</keycap></term> |
f37d3835 ZJS |
145 | <listitem><para>Make selected entry the default</para></listitem> |
146 | </varlistentry> | |
147 | ||
148 | <varlistentry> | |
8c073dde | 149 | <term><keycap>e</keycap></term> |
f37d3835 ZJS |
150 | <listitem><para>Edit the kernel command line for selected entry</para></listitem> |
151 | </varlistentry> | |
152 | ||
153 | <varlistentry> | |
8c073dde LP |
154 | <term><keycap>+</keycap></term> |
155 | <term><keycap>t</keycap></term> | |
f37d3835 ZJS |
156 | <listitem><para>Increase the timeout before default entry is booted</para></listitem> |
157 | </varlistentry> | |
158 | ||
159 | <varlistentry> | |
8c073dde LP |
160 | <term><keycap>-</keycap></term> |
161 | <term><keycap>T</keycap></term> | |
f37d3835 ZJS |
162 | <listitem><para>Decrease the timeout</para></listitem> |
163 | </varlistentry> | |
164 | ||
1b965abc JJ |
165 | <varlistentry> |
166 | <term><keycap>r</keycap></term> | |
167 | <listitem><para>Change screen resolution, skipping any unsupported modes.</para></listitem> | |
168 | </varlistentry> | |
169 | ||
170 | <varlistentry> | |
171 | <term><keycap>R</keycap></term> | |
172 | <listitem><para>Reset screen resolution to firmware or configuration file default.</para></listitem> | |
173 | </varlistentry> | |
174 | ||
f37d3835 | 175 | <varlistentry> |
8a8e5666 | 176 | <term><keycap>p</keycap></term> |
f37d3835 ZJS |
177 | <listitem><para>Print status</para></listitem> |
178 | </varlistentry> | |
179 | ||
f37d3835 | 180 | <varlistentry> |
8c073dde LP |
181 | <term><keycap>h</keycap></term> |
182 | <term><keycap>?</keycap></term> | |
a318a565 | 183 | <term><keycap>F1</keycap></term> |
f37d3835 ZJS |
184 | <listitem><para>Show a help screen</para></listitem> |
185 | </varlistentry> | |
e6cab77e JJ |
186 | |
187 | <varlistentry> | |
188 | <term><keycap>f</keycap></term> | |
189 | <listitem><para>Reboot into firmware interface.</para> | |
190 | ||
191 | <para>For compatibility with the keybindings of several firmware implementations this operation | |
192 | may also be reached with <keycap>F2</keycap>, <keycap>F10</keycap>, <keycap>Del</keycap> and | |
193 | <keycap>Esc</keycap>.</para></listitem> | |
194 | </varlistentry> | |
f37d3835 ZJS |
195 | </variablelist> |
196 | ||
e14a0c21 LP |
197 | <para>The following keys may be pressed during bootup or in the boot menu to directly boot a specific |
198 | entry:</para> | |
f37d3835 ZJS |
199 | |
200 | <variablelist> | |
201 | <varlistentry> | |
8c073dde | 202 | <term><keycap>l</keycap></term> |
f37d3835 ZJS |
203 | <listitem><para>Linux</para></listitem> |
204 | </varlistentry> | |
205 | ||
206 | <varlistentry> | |
8c073dde | 207 | <term><keycap>w</keycap></term> |
f37d3835 ZJS |
208 | <listitem><para>Windows</para></listitem> |
209 | </varlistentry> | |
210 | ||
211 | <varlistentry> | |
8c073dde | 212 | <term><keycap>a</keycap></term> |
6d3831ce | 213 | <listitem><para>macOS</para></listitem> |
f37d3835 ZJS |
214 | </varlistentry> |
215 | ||
216 | <varlistentry> | |
8c073dde | 217 | <term><keycap>s</keycap></term> |
f37d3835 ZJS |
218 | <listitem><para>EFI shell</para></listitem> |
219 | </varlistentry> | |
220 | ||
221 | <varlistentry> | |
8c073dde LP |
222 | <term><keycap>1</keycap></term> |
223 | <term><keycap>2</keycap></term> | |
224 | <term><keycap>3</keycap></term> | |
225 | <term><keycap>4</keycap></term> | |
226 | <term><keycap>5</keycap></term> | |
227 | <term><keycap>6</keycap></term> | |
228 | <term><keycap>7</keycap></term> | |
229 | <term><keycap>8</keycap></term> | |
230 | <term><keycap>9</keycap></term> | |
53ddb667 | 231 | <listitem><para>Boot entry number 1 … 9</para></listitem> |
f37d3835 ZJS |
232 | </varlistentry> |
233 | </variablelist> | |
234 | ||
e14a0c21 LP |
235 | <para>The boot menu is shown when a non-zero menu timeout has been configured. If the menu timeout has |
236 | been set to zero, it is sufficient to press any key — before the boot loader initializes — to bring up | |
237 | the boot menu, except for the keys listed immediately above as they directly boot into the selected boot | |
238 | menu item. Note that depending on the firmware implementation the time window where key presses are | |
239 | accepted before the boot loader initializes might be short. If the window is missed, reboot and try | |
240 | again, possibly pressing a suitable key (e.g. the space bar) continuously; on most systems it should be | |
241 | possible to hit the time window after a few attempts. To avoid this problem, consider setting a non-zero | |
242 | timeout, thus showing the boot menu unconditionally. Some desktop environments might offer an option to | |
243 | directly boot into the boot menu, to avoid the problem altogether. Alternatively, use the command line | |
244 | <command>systemctl reboot --boot-loader-menu=0</command> from the shell.</para> | |
245 | ||
f37d3835 ZJS |
246 | <para>In the editor, most keys simply insert themselves, but the following keys |
247 | may be used to perform additional actions:</para> | |
248 | ||
249 | <variablelist> | |
250 | <varlistentry> | |
8c073dde LP |
251 | <term><keycap>←</keycap> (Left)</term> |
252 | <term><keycap>→</keycap> (Right)</term> | |
253 | <term><keycap>Home</keycap></term> | |
254 | <term><keycap>End</keycap></term> | |
f37d3835 ZJS |
255 | <listitem><para>Navigate left/right</para></listitem> |
256 | </varlistentry> | |
257 | ||
258 | <varlistentry> | |
8c073dde | 259 | <term><keycap>Esc</keycap></term> |
230f7820 | 260 | <term><keycombo><keycap>Ctrl</keycap><keycap>c</keycap></keycombo></term> |
f37d3835 ZJS |
261 | <listitem><para>Abort the edit and quit the editor</para></listitem> |
262 | </varlistentry> | |
263 | ||
264 | <varlistentry> | |
8c073dde | 265 | <term><keycombo><keycap>Ctrl</keycap><keycap>k</keycap></keycombo></term> |
230f7820 | 266 | <listitem><para>Clear the command line forwards</para></listitem> |
f37d3835 ZJS |
267 | </varlistentry> |
268 | ||
269 | <varlistentry> | |
8c073dde LP |
270 | <term><keycombo><keycap>Ctrl</keycap><keycap>w</keycap></keycombo></term> |
271 | <term><keycombo><keycap>Alt</keycap><keycap>Backspace</keycap></keycombo></term> | |
f37d3835 ZJS |
272 | <listitem><para>Delete word backwards</para></listitem> |
273 | </varlistentry> | |
274 | ||
275 | <varlistentry> | |
230f7820 | 276 | <term><keycombo><keycap>Ctrl</keycap><keycap>Del</keycap></keycombo></term> |
8c073dde | 277 | <term><keycombo><keycap>Alt</keycap><keycap>d</keycap></keycombo></term> |
f37d3835 ZJS |
278 | <listitem><para>Delete word forwards</para></listitem> |
279 | </varlistentry> | |
280 | ||
281 | <varlistentry> | |
8c073dde | 282 | <term><keycap>↵</keycap> (Enter)</term> |
f37d3835 ZJS |
283 | <listitem><para>Boot entry with the edited command line</para></listitem> |
284 | </varlistentry> | |
285 | </variablelist> | |
286 | ||
70c8db75 | 287 | <para>Note that unless configured otherwise in the UEFI firmware, systemd-boot will |
f37d3835 ZJS |
288 | use the US keyboard layout, so key labels might not match for keys like +/-. |
289 | </para> | |
290 | </refsect1> | |
291 | ||
53ddb667 LP |
292 | <refsect1> |
293 | <title>Files</title> | |
294 | ||
c5fcaed8 LP |
295 | <para>The files <command>systemd-boot</command> processes generally reside on the UEFI ESP which is |
296 | usually mounted to <filename>/efi/</filename>, <filename>/boot/</filename> or | |
297 | <filename>/boot/efi/</filename> during OS runtime. It also processes files on the Extended Boot Loader | |
298 | partition which is typically mounted to <filename>/boot/</filename>, if it | |
99d51ed9 LP |
299 | exists.</para> |
300 | ||
301 | <para><command>systemd-boot</command> reads runtime configuration such as the boot timeout and default | |
c5fcaed8 LP |
302 | entry from <filename>/loader/loader.conf</filename> on the ESP (in combination with data read from EFI |
303 | variables). See | |
99d51ed9 LP |
304 | <citerefentry><refentrytitle>loader.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
305 | ||
306 | <para>Boot entry description files following the <ulink | |
db811444 | 307 | url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink> are read from |
99d51ed9 LP |
308 | <filename>/loader/entries/</filename> on the ESP and the Extended Boot Loader partition.</para> |
309 | ||
310 | <para>Unified kernel boot entries following the <ulink | |
db811444 | 311 | url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink> are read from |
99d51ed9 LP |
312 | <filename>/EFI/Linux/</filename> on the ESP and the Extended Boot Loader partition.</para> |
313 | ||
314 | <para>Optionally, a random seed for early boot entropy pool provisioning is stored in | |
315 | <filename>/loader/random-seed</filename> in the ESP.</para> | |
316 | ||
317 | <para>During initialization, <command>sd-boot</command> automatically loads all driver files placed in | |
318 | the <filename>/EFI/systemd/drivers/</filename> directory of the ESP. The files placed there must have an | |
319 | extension of the EFI architecture ID followed by <filename>.efi</filename> (e.g. for x86-64 this means a | |
320 | suffix of <filename>x64.efi</filename>). This may be used to automatically load file system drivers and | |
321 | similar, to extend the native firmware support.</para> | |
e6b0cfad VD |
322 | |
323 | <para>Enrollment of Secure Boot variables can be performed manually or automatically if files are available | |
8d41101a | 324 | under <filename>/loader/keys/<replaceable>NAME</replaceable>/{db,KEK,PK}.auth</filename>, <replaceable>NAME</replaceable> |
e6b0cfad VD |
325 | being the display name for the set of variables in the menu. If one of the sets is named <filename>auto</filename> |
326 | then it might be enrolled automatically depending on whether <literal>secure-boot-enroll</literal> is set | |
327 | to force or not.</para> | |
53ddb667 LP |
328 | </refsect1> |
329 | ||
8eebff9e LP |
330 | <refsect1> |
331 | <title>EFI Variables</title> | |
332 | ||
b8cdb662 LP |
333 | <para>The following EFI variables are defined, set and read by <command>systemd-boot</command>, under the |
334 | vendor UUID <literal>4a67b082-0a4c-41cf-b6c7-440b29bb8c4f</literal>, for communication between the boot | |
335 | loader and the OS:</para> | |
8eebff9e | 336 | |
bc61c2b1 | 337 | <variablelist class='efi-variables'> |
8eebff9e LP |
338 | <varlistentry> |
339 | <term><varname>LoaderBootCountPath</varname></term> | |
340 | <listitem><para>If boot counting is enabled, contains the path to the file in whose name the boot counters are | |
341 | encoded. Set by the boot | |
342 | loader. <citerefentry><refentrytitle>systemd-bless-boot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
343 | uses this information to mark a boot as successful as determined by the successful activation of the | |
344 | <filename>boot-complete.target</filename> target unit.</para></listitem> | |
345 | </varlistentry> | |
346 | ||
347 | <varlistentry> | |
348 | <term><varname>LoaderConfigTimeout</varname></term> | |
fe2579dd | 349 | <term><varname>LoaderConfigTimeoutOneShot</varname></term> |
3f9a0a52 | 350 | <listitem><para>The menu timeout in seconds. Read by the boot loader. <varname>LoaderConfigTimeout</varname> |
fe2579dd LP |
351 | is maintained persistently, while <varname>LoaderConfigTimeoutOneShot</varname> is a one-time override which is |
352 | read once (in which case it takes precedence over <varname>LoaderConfigTimeout</varname>) and then | |
353 | removed. <varname>LoaderConfigTimeout</varname> may be manipulated with the | |
e9dd6984 | 354 | <keycap>t</keycap>/<keycap>T</keycap> keys, see above.</para></listitem> |
8eebff9e LP |
355 | </varlistentry> |
356 | ||
357 | <varlistentry> | |
358 | <term><varname>LoaderDevicePartUUID</varname></term> | |
359 | ||
360 | <listitem><para>Contains the partition UUID of the EFI System Partition the boot loader was run from. Set by | |
361 | the boot | |
362 | loader. <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
363 | uses this information to automatically find the disk booted from, in order to discover various other partitions | |
364 | on the same disk automatically.</para></listitem> | |
365 | </varlistentry> | |
366 | ||
367 | <varlistentry> | |
368 | <term><varname>LoaderEntries</varname></term> | |
369 | ||
370 | <listitem><para>A list of the identifiers of all discovered boot loader entries. Set by the boot | |
371 | loader.</para></listitem> | |
372 | </varlistentry> | |
373 | ||
374 | <varlistentry> | |
375 | <term><varname>LoaderEntryDefault</varname></term> | |
376 | <term><varname>LoaderEntryOneShot</varname></term> | |
377 | ||
378 | <listitem><para>The identifier of the default boot loader entry. Set primarily by the OS and read by the boot | |
379 | loader. <varname>LoaderEntryOneShot</varname> sets the default entry for the next boot only, while | |
380 | <varname>LoaderEntryDefault</varname> sets it persistently for all future | |
381 | boots. <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s | |
382 | <option>set-default</option> and <option>set-oneshot</option> commands make use of these variables. The boot | |
383 | loader modifies <varname>LoaderEntryDefault</varname> on request, when the <keycap>d</keycap> key is used, see | |
f4e1a425 | 384 | above.</para></listitem> |
8eebff9e LP |
385 | </varlistentry> |
386 | ||
387 | <varlistentry> | |
388 | <term><varname>LoaderEntrySelected</varname></term> | |
389 | ||
390 | <listitem><para>The identifier of the boot loader entry currently being booted. Set by the boot | |
391 | loader.</para></listitem> | |
392 | </varlistentry> | |
393 | ||
5dd5f7cf LP |
394 | <varlistentry> |
395 | <term><varname>LoaderFeatures</varname></term> | |
396 | ||
397 | <listitem><para>A set of flags indicating the features the boot loader supports. Set by the boot loader. Use | |
398 | <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to view this | |
399 | data.</para></listitem> | |
400 | </varlistentry> | |
401 | ||
8eebff9e LP |
402 | <varlistentry> |
403 | <term><varname>LoaderFirmwareInfo</varname></term> | |
404 | <term><varname>LoaderFirmwareType</varname></term> | |
405 | ||
406 | <listitem><para>Brief firmware information. Set by the boot loader. Use | |
407 | <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to view this | |
408 | data.</para></listitem> | |
409 | </varlistentry> | |
410 | ||
411 | <varlistentry> | |
412 | <term><varname>LoaderImageIdentifier</varname></term> | |
413 | ||
414 | <listitem><para>The path of executable of the boot loader used for the current boot, relative to the EFI System | |
415 | Partition's root directory. Set by the boot loader. Use | |
416 | <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to view this | |
417 | data.</para></listitem> | |
418 | </varlistentry> | |
419 | ||
420 | <varlistentry> | |
421 | <term><varname>LoaderInfo</varname></term> | |
422 | ||
423 | <listitem><para>Brief information about the boot loader. Set by the boot loader. Use | |
424 | <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> to view this | |
425 | data.</para></listitem> | |
426 | </varlistentry> | |
427 | ||
428 | <varlistentry> | |
429 | <term><varname>LoaderTimeExecUSec</varname></term> | |
430 | <term><varname>LoaderTimeInitUSec</varname></term> | |
431 | <term><varname>LoaderTimeMenuUsec</varname></term> | |
432 | ||
433 | <listitem><para>Information about the time spent in various parts of the boot loader. Set by the boot | |
434 | loader. Use <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
39867bb9 LP |
435 | to view this data. </para></listitem> |
436 | </varlistentry> | |
437 | ||
39867bb9 LP |
438 | <varlistentry> |
439 | <term><varname>LoaderSystemToken</varname></term> | |
440 | ||
e9dd6984 ZJS |
441 | <listitem><para>A binary random data field, that is used for generating the random seed to pass to |
442 | the OS (see above). Note that this random data is generally only generated once, during OS | |
443 | installation, and is then never updated again.</para></listitem> | |
8eebff9e LP |
444 | </varlistentry> |
445 | </variablelist> | |
39867bb9 LP |
446 | |
447 | <para>Many of these variables are defined by the <ulink | |
448 | url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader Interface</ulink>.</para> | |
8eebff9e LP |
449 | </refsect1> |
450 | ||
2b6cc3ca LP |
451 | <refsect1> |
452 | <title>Boot Counting</title> | |
453 | ||
454 | <para><command>systemd-boot</command> implements a simple boot counting mechanism on top of the <ulink | |
db811444 | 455 | url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink>, for automatic and unattended |
5238e957 | 456 | fallback to older kernel versions/boot loader entries when a specific entry continuously fails. Any boot loader |
2b6cc3ca LP |
457 | entry file and unified kernel image file that contains a <literal>+</literal> followed by one or two numbers (if |
458 | two they need to be separated by a <literal>-</literal>), before the <filename>.conf</filename> or | |
459 | <filename>.efi</filename> suffix is subject to boot counting: the first of the two numbers ('tries left') is | |
460 | decreased by one on every boot attempt, the second of the two numbers ('tries done') is increased by one (if 'tries | |
461 | done' is absent it is considered equivalent to 0). Depending on the current value of these two counters the boot | |
462 | entry is considered to be in one of three states:</para> | |
463 | ||
464 | <orderedlist> | |
465 | <listitem><para>If the 'tries left' counter of an entry is greater than zero the entry is considered to be in | |
466 | 'indeterminate' state. This means the entry has not completed booting successfully yet, but also hasn't been | |
467 | determined not to work.</para></listitem> | |
468 | ||
469 | <listitem><para>If the 'tries left' counter of an entry is zero it is considered to be in 'bad' state. This means | |
470 | no further attempts to boot this item will be made (that is, unless all other boot entries are also in 'bad' | |
471 | state), as all attempts to boot this entry have not completed successfully.</para></listitem> | |
472 | ||
473 | <listitem><para>If the 'tries left' and 'tries done' counters of an entry are absent it is considered to be in | |
474 | 'good' state. This means further boot counting for the entry is turned off, as it successfully booted at least | |
475 | once. The | |
476 | <citerefentry><refentrytitle>systemd-bless-boot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
477 | service moves the currently booted entry from 'indeterminate' into 'good' state when a boot attempt completed | |
478 | successfully.</para></listitem> | |
479 | </orderedlist> | |
480 | ||
481 | <para>Generally, when new entries are added to the boot loader, they first start out in 'indeterminate' state, | |
482 | i.e. with a 'tries left' counter greater than zero. The boot entry remains in this state until either it managed to | |
483 | complete a full boot successfully at least once (in which case it will be in 'good' state) — or the 'tries left' | |
484 | counter reaches zero (in which case it will be in 'bad' state).</para> | |
485 | ||
486 | <para>Example: let's say a boot loader entry file <filename>foo.conf</filename> is set up for 3 boot tries. The | |
487 | installer will hence create it under the name <filename>foo+3.conf</filename>. On first boot, the boot loader will | |
488 | rename it to <filename>foo+2-1.conf</filename>. If that boot does not complete successfully, the boot loader will | |
489 | rename it to <filename>foo+1-2.conf</filename> on the following boot. If that fails too, it will finally be renamed | |
490 | <filename>foo+0-3.conf</filename> by the boot loader on next boot, after which it will be considered 'bad'. If the | |
491 | boot succeeds however the entry file will be renamed to <filename>foo.conf</filename> by the OS, so that it is | |
492 | considered 'good' from then on.</para> | |
493 | ||
494 | <para>The boot menu takes the 'tries left' counter into account when sorting the menu entries: entries in 'bad' | |
f65a3326 LP |
495 | state are ordered at the beginning of the list, and entries in 'good' or 'indeterminate' at the end. The user can |
496 | freely choose to boot any entry of the menu, including those already marked 'bad'. If the menu entry to boot is | |
497 | automatically determined, this means that 'good' or 'indeterminate' entries are generally preferred (as the bottom | |
498 | item of the menu is the one booted by default), and 'bad' entries will only be considered if there are no 'good' or | |
2b6cc3ca LP |
499 | 'indeterminate' entries left.</para> |
500 | ||
501 | <para>The <citerefentry><refentrytitle>kernel-install</refentrytitle><manvolnum>8</manvolnum></citerefentry> kernel | |
502 | install framework optionally sets the initial 'tries left' counter to the value specified in | |
503 | <filename>/etc/kernel/tries</filename> when a boot loader entry is first created.</para> | |
504 | </refsect1> | |
505 | ||
941d418d GH |
506 | <refsect1> |
507 | <title>Using systemd-boot in virtual machines.</title> | |
508 | ||
509 | <para>When using qemu with OVMF (UEFI Firmware for virtual machines) the <option>-kernel</option> switch | |
510 | works not only for linux kernels, but for any EFI binary, including sd-boot and unified linux | |
511 | kernels. Example command line for loading sd-boot on x64:</para> | |
512 | ||
513 | <para> | |
514 | <command>qemu-system-x86_64 <replaceable>[ ... ]</replaceable> | |
515 | -kernel /usr/lib/systemd/boot/efi/systemd-bootx64.efi</command> | |
516 | </para> | |
517 | ||
518 | <para>systemd-boot will detect that it was started directly instead of being loaded from ESP and will | |
519 | search for the ESP in that case, taking into account boot order information from the hypervisor (if | |
520 | available).</para> | |
521 | </refsect1> | |
522 | ||
f37d3835 ZJS |
523 | <refsect1> |
524 | <title>See Also</title> | |
525 | <para> | |
526 | <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
527 | <citerefentry><refentrytitle>loader.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
2b6cc3ca | 528 | <citerefentry><refentrytitle>systemd-bless-boot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
921fc451 | 529 | <citerefentry><refentrytitle>systemd-boot-random-seed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
2b6cc3ca | 530 | <citerefentry><refentrytitle>kernel-install</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
3f9a615d | 531 | <citerefentry><refentrytitle>systemd-stub</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
db811444 | 532 | <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink>, |
2fe82132 | 533 | <ulink url="https://systemd.io/BOOT_LOADER_INTERFACE">Boot Loader Interface</ulink> |
f37d3835 ZJS |
534 | </para> |
535 | </refsect1> | |
536 | </refentry> |