summaryrefslogtreecommitdiffstats
path: root/man/kernel-command-line.xml
blob: 2e60beb98bfb529e38ff2fbe45930a6077b07018 (plain)
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
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
<?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-or-later -->

<refentry id="kernel-command-line">

  <refentryinfo>
    <title>kernel-command-line</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>kernel-command-line</refentrytitle>
    <manvolnum>7</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>kernel-command-line</refname>
    <refpurpose>Kernel command line parameters</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>/proc/cmdline</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The kernel, the programs running in the initrd and in the host system may be configured at boot via
    kernel command line arguments. In addition, various systemd tools look at the EFI variable
    <literal>SystemdOptions</literal> (if available). Both sources are combined, but the kernel command line
    has higher priority. Please note that <emphasis>the EFI variable is only used by systemd tools, and is
    ignored by the kernel and other user space tools</emphasis>, so it is not a replacement for the kernel
    command line.</para>

    <para>For command line parameters understood by the kernel, please
    see
    <ulink url="https://docs.kernel.org/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
    and
    <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>

    <para>For command line parameters understood by the initrd, see
    <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
    or the documentation of the specific initrd implementation of your
    installation.</para>
  </refsect1>

  <refsect1>
    <title>Core OS Command Line Arguments</title>

    <variablelist class='kernel-commandline-options'>
      <varlistentry>
        <term><varname>systemd.unit=</varname></term>
        <term><varname>rd.systemd.unit=</varname></term>
        <term><varname>systemd.dump_core</varname></term>
        <term><varname>systemd.crash_chvt</varname></term>
        <term><varname>systemd.crash_shell</varname></term>
        <term><varname>systemd.crash_reboot</varname></term>
        <term><varname>systemd.confirm_spawn</varname></term>
        <term><varname>systemd.service_watchdogs</varname></term>
        <term><varname>systemd.show_status</varname></term>
        <term><varname>systemd.status_unit_format=</varname></term>
        <term><varname>systemd.log_target=</varname></term>
        <term><varname>systemd.log_level=</varname></term>
        <term><varname>systemd.log_location=</varname></term>
        <term><varname>systemd.log_color</varname></term>
        <term><varname>systemd.default_standard_output=</varname></term>
        <term><varname>systemd.default_standard_error=</varname></term>
        <term><varname>systemd.setenv=</varname></term>
        <term><varname>systemd.machine_id=</varname></term>
        <term><varname>systemd.set_credential=</varname></term>
        <term><varname>systemd.import_credentials=</varname></term>
        <listitem>
          <para>Parameters understood by the system and service
          manager to control system behavior. For details, see
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.mask=</varname></term>
        <term><varname>systemd.wants=</varname></term>
        <term><varname>systemd.debug_shell</varname></term>
        <listitem>
          <para>Additional parameters understood by
          <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
          to mask or start specific units at boot, or invoke a debug
          shell on tty9.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.run=</varname></term>
        <term><varname>systemd.run_success_action=</varname></term>
        <term><varname>systemd.run_failure_action=</varname></term>
        <listitem>
          <para>Additional parameters understood by
          <citerefentry><refentrytitle>systemd-run-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, to
          run a command line specified on the kernel command line as system service after booting up.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.early_core_pattern=</varname></term>
        <listitem>
          <para>During early boot, the generation of core dump files is disabled until a core dump handler (if any)
          takes over. This parameter allows specifying an absolute path where core dump files should be stored until
          a handler is installed. The path should be absolute and may contain specifiers, see
          <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.restore_state=</varname></term>
        <listitem>
          <para>This parameter is understood by several system tools
          to control whether or not they should restore system state
          from the previous boot. For details, see
          <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          and
          <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.volatile=</varname></term>
        <listitem>
          <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
          the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
          directory and <filename>/var/</filename> are mounted as specified on the kernel command line or
          <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
          this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
          <filename>/usr/</filename> is mounted from the file system configured as root device, in read-only mode. This
          enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
          configuration and no stored state in effect, as <filename>/etc/</filename> and <filename>/var/</filename> (as
          well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
          setting is set to <literal>state</literal> the root file system is mounted read-only, however
          <filename>/var/</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
          system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If
          this setting is set to <literal>overlay</literal> the root file system is set up as
          <literal>overlayfs</literal> mount combining the read-only root directory with a writable
          <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
          nonetheless with all changes being lost at reboot. For details, see
          <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          and
          <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>quiet</varname></term>
        <listitem>
          <para>Parameter understood by both the kernel and the system
          and service manager to control console log verbosity. For
          details, see
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>debug</varname></term>
        <listitem>
          <para>Parameter understood by both the kernel and the system
          and service manager to control console log verbosity. For
          details, see
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>-b</varname></term>
        <term><varname>rd.emergency</varname></term>
        <term><varname>emergency</varname></term>
        <term><varname>rd.rescue</varname></term>
        <term><varname>rescue</varname></term>
        <term><varname>single</varname></term>
        <term><varname>s</varname></term>
        <term><varname>S</varname></term>
        <term><varname>1</varname></term>
        <term><varname>2</varname></term>
        <term><varname>3</varname></term>
        <term><varname>4</varname></term>
        <term><varname>5</varname></term>
        <listitem>
          <para>Parameters understood by the system and service
          manager, as compatibility and convenience options. For details, see
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>locale.LANG=</varname></term>
        <term><varname>locale.LANGUAGE=</varname></term>
        <term><varname>locale.LC_CTYPE=</varname></term>
        <term><varname>locale.LC_NUMERIC=</varname></term>
        <term><varname>locale.LC_TIME=</varname></term>
        <term><varname>locale.LC_COLLATE=</varname></term>
        <term><varname>locale.LC_MONETARY=</varname></term>
        <term><varname>locale.LC_MESSAGES=</varname></term>
        <term><varname>locale.LC_PAPER=</varname></term>
        <term><varname>locale.LC_NAME=</varname></term>
        <term><varname>locale.LC_ADDRESS=</varname></term>
        <term><varname>locale.LC_TELEPHONE=</varname></term>
        <term><varname>locale.LC_MEASUREMENT=</varname></term>
        <term><varname>locale.LC_IDENTIFICATION=</varname></term>
        <listitem>
          <para>Parameters understood by the system and service
          manager to control locale and language settings. For
          details, see
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>fsck.mode=</varname></term>
        <term><varname>fsck.repair=</varname></term>

        <listitem>
          <para>Parameters understood by the file system checker
          services. For details, see
          <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>quotacheck.mode=</varname></term>

        <listitem>
          <para>Parameter understood by the file quota checker
          service. For details, see
          <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.journald.forward_to_syslog=</varname></term>
        <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
        <term><varname>systemd.journald.forward_to_console=</varname></term>
        <term><varname>systemd.journald.forward_to_wall=</varname></term>

        <listitem>
          <para>Parameters understood by the journal service. For
          details, see
          <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>vconsole.keymap=</varname></term>
        <term><varname>vconsole.keymap_toggle=</varname></term>
        <term><varname>vconsole.font=</varname></term>
        <term><varname>vconsole.font_map=</varname></term>
        <term><varname>vconsole.font_unimap=</varname></term>

        <listitem>
          <para>Parameters understood by the virtual console setup logic. For details, see
          <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>udev.log_level=</varname></term>
        <term><varname>rd.udev.log_level=</varname></term>
        <term><varname>udev.children_max=</varname></term>
        <term><varname>rd.udev.children_max=</varname></term>
        <term><varname>udev.exec_delay=</varname></term>
        <term><varname>rd.udev.exec_delay=</varname></term>
        <term><varname>udev.event_timeout=</varname></term>
        <term><varname>rd.udev.event_timeout=</varname></term>
        <term><varname>udev.timeout_signal=</varname></term>
        <term><varname>rd.udev.timeout_signal=</varname></term>
        <term><varname>udev.blockdev_read_only</varname></term>
        <term><varname>rd.udev.blockdev_read_only</varname></term>
        <term><varname>net.ifnames=</varname></term>
        <term><varname>net.naming-scheme=</varname></term>

        <listitem>
          <para>Parameters understood by the device event managing
          daemon. For details, see
          <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>plymouth.enable=</varname></term>

        <listitem>
          <para>May be used to disable the Plymouth boot splash. For
          details, see
          <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>luks=</varname></term>
        <term><varname>rd.luks=</varname></term>
        <term><varname>luks.crypttab=</varname></term>
        <term><varname>rd.luks.crypttab=</varname></term>
        <term><varname>luks.name=</varname></term>
        <term><varname>rd.luks.name=</varname></term>
        <term><varname>luks.uuid=</varname></term>
        <term><varname>rd.luks.uuid=</varname></term>
        <term><varname>luks.options=</varname></term>
        <term><varname>rd.luks.options=</varname></term>
        <term><varname>luks.key=</varname></term>
        <term><varname>rd.luks.key=</varname></term>

        <listitem>
          <para>Configures the LUKS full-disk encryption logic at
          boot. For details, see
          <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>fstab=</varname></term>
        <term><varname>rd.fstab=</varname></term>

        <listitem>
          <para>Configures the <filename>/etc/fstab</filename> logic
          at boot. For details, see
          <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>root=</varname></term>
        <term><varname>rootfstype=</varname></term>
        <term><varname>rootflags=</varname></term>
        <term><varname>ro</varname></term>
        <term><varname>rw</varname></term>

        <listitem>
          <para>Configures the root file system and its file system
          type and mount options, as well as whether it shall be
          mounted read-only or read-write initially. For details,
          see
          <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>mount.usr=</varname></term>
        <term><varname>mount.usrfstype=</varname></term>
        <term><varname>mount.usrflags=</varname></term>

        <listitem>
          <para>Configures the /usr file system (if required) and
          its file system type and mount options. For details, see
          <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>veritytab=</varname></term>
        <term><varname>rd.veritytab=</varname></term>
        <term><varname>roothash=</varname></term>
        <term><varname>systemd.verity=</varname></term>
        <term><varname>rd.systemd.verity=</varname></term>
        <term><varname>systemd.verity_root_data=</varname></term>
        <term><varname>systemd.verity_root_hash=</varname></term>
        <term><varname>systemd.verity.root_options=</varname></term>
        <term><varname>usrhash=</varname></term>
        <term><varname>systemd.verity_usr_data=</varname></term>
        <term><varname>systemd.verity_usr_hash=</varname></term>
        <term><varname>systemd.verity_usr_options=</varname></term>
        <listitem>
          <para>Configures the integrity protection root hash for the root and <filename>/usr</filename> file systems, and other related
          parameters. For details, see
          <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.getty_auto=</varname></term>

        <listitem>
          <para>Configures whether the <filename>serial-getty@.service</filename> will run.
          For details, see
          <citerefentry><refentrytitle>systemd-getty-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.gpt_auto=</varname></term>
        <term><varname>rd.systemd.gpt_auto=</varname></term>

        <listitem>
          <para>Configures whether GPT based partition auto-discovery
          shall be attempted. For details, see
          <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.default_timeout_start_sec=</varname></term>

        <listitem>
          <para>Overrides the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at
          boot. For details, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.watchdog_device=</varname></term>

        <listitem>
          <para>Overrides the watchdog device path <varname>WatchdogDevice=</varname>. For details, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.watchdog_sec=</varname></term>

        <listitem>
          <para>Overrides the watchdog timeout settings otherwise configured with
          <varname>RuntimeWatchdog=</varname>, <varname>RebootWatchdog=</varname> and
          <varname>KExecWatchdogSec=</varname>. Takes a time value (if no unit is specified, seconds is the
          implicitly assumed time unit) or the special strings <literal>off</literal> or
          <literal>default</literal>. For details, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.watchdog_pre_sec=</varname></term>

        <listitem>
          <para>Overrides the watchdog pre-timeout settings otherwise configured with
          <varname>RuntimeWatchdogPreSec=</varname>. Takes a time value (if no unit is specified, seconds is the
          implicitly assumed time unit) or the special strings <literal>off</literal> or
          <literal>default</literal>. For details, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.watchdog_pretimeout_governor=</varname></term>

        <listitem>
          <para>Overrides the watchdog pre-timeout settings otherwise configured with
          <varname>RuntimeWatchdogPreGovernor=</varname>. Takes a string value. For details, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.cpu_affinity=</varname></term>

        <listitem>
          <para>Overrides the CPU affinity mask for the service manager and the default for all child
          processes it forks. This takes precedence over <varname>CPUAffinity=</varname>, see
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
          for details.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>modules_load=</varname></term>
        <term><varname>rd.modules_load=</varname></term>

        <listitem>
          <para>Load a specific kernel module early at boot. For
          details, see
          <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>resume=</varname></term>
        <term><varname>resumeflags=</varname></term>

        <listitem>
          <para>Enables resume from hibernation using the specified
          device and mount options. All
          <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
          paths are supported. For details, see
          <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.firstboot=</varname></term>

        <listitem><para>Takes a boolean argument, defaults to on. If off,
        <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        will not query the user for basic system settings, even if the system boots up for the first time and
        the relevant settings are not initialized yet. Not to be confused with
        <varname>systemd.condition-first-boot=</varname> (see below), which overrides the result of the
        <varname>ConditionFirstBoot=</varname> unit file condition, and thus controls more than just
        <filename>systemd-firstboot.service</filename> behaviour.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.condition-needs-update=</varname></term>

        <listitem><para>Takes a boolean argument. If specified, overrides the result of
        <varname>ConditionNeedsUpdate=</varname> unit condition checks. See
        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
        details.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.condition-first-boot=</varname></term>

        <listitem><para>Takes a boolean argument. If specified, overrides the result of
        <varname>ConditionFirstBoot=</varname> unit condition checks. See
        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
        details. Not to be confused with <varname>systemd.firstboot=</varname> which only controls behaviour
        of the <filename>systemd-firstboot.service</filename> system service but has no effect on the
        condition check (see above).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.clock-usec=</varname></term>

        <listitem><para>Takes a decimal, numeric timestamp in µs since January 1st 1970, 00:00am, to set the
        system clock to. The system time is set to the specified timestamp early during boot. It is not
        propagated to the hardware clock (RTC).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.random-seed=</varname></term>

        <listitem><para>Takes a base64 encoded random seed value to credit with full entropy to the kernel's
        random pool during early service manager initialization. This option is useful in testing
        environments where delays due to random pool initialization in entropy starved virtual machines shall
        be avoided.</para>

        <para>Note that if this option is used the seed is accessible to unprivileged programs from
        <filename>/proc/cmdline</filename>. This option is hence a security risk when used outside of test
        systems, since the (possibly) only seed used for initialization of the kernel's entropy pool might be
        easily acquired by unprivileged programs.</para>

        <para>It is recommended to pass 512 bytes of randomized data (as that matches the Linux kernel pool
        size), which may be generated with a command like the following:</para>

        <programlisting>dd if=/dev/urandom bs=512 count=1 status=none | base64 -w 0</programlisting>

        <para>Again: do not use this option outside of testing environments, it's a security risk elsewhere,
        as secret key material derived from the entropy pool can possibly be reconstructed by unprivileged
        programs.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>systemd.hostname=</varname></term>

        <listitem><para>Accepts a hostname to set during early boot. If specified takes precedence over what
        is set in <filename>/etc/hostname</filename>. Note that this does not bar later runtime changes to
        the hostname, it simply controls the initial hostname set during early boot.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
      <title>History</title>

      <variablelist>
        <varlistentry>
          <term>systemd 252</term>
          <listitem><para>Kernel command-line arguments <varname>systemd.unified_cgroup_hierarchy</varname>
          and <varname>systemd.legacy_systemd_cgroup_controller</varname> were deprecated. Please switch to
          the unified cgroup hierarchy.</para></listitem>
        </varlistentry>
      </variablelist>
  </refsect1>

  <refsect1>
      <title>See Also</title>
      <para>
        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
        <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
        <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-getty-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
        <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
      </para>
  </refsect1>

</refentry>