systemd-debug-generator - Generator for enabling a runtime debug shell and masking specific units at boot

       systemd-debug-generator is a generator that reads the kernel command line and understands three options:

       If the systemd.mask= or rd.systemd.mask= option is specified and followed by a unit name, this unit is
       masked for the runtime (i.e. for this session — from boot to shutdown), similarly to the effect of
       systemctl(1)'s mask command. This is useful to boot with certain units removed from the initial boot
       transaction for debugging system startup. May be specified more than once.  rd.systemd.mask= is honored
       only by initial RAM disk (initrd) while systemd.mask= is honored only in the main system.

       If the systemd.wants= or rd.systemd.wants= option is specified and followed by a unit name, a start job
       for this unit is added to the initial transaction. This is useful to start one or more additional units
       at boot. May be specified more than once.  rd.systemd.wants= is honored only by initial RAM disk (initrd)
       while systemd.wants= is honored only in the main system.

       If the systemd.debug_shell or rd.systemd.debug_shell option is specified, the debug shell service
       "debug-shell.service" is pulled into the boot transaction and a debug shell will be spawned during early
       boot. By default, /dev/tty9 is used, but a specific tty can also be specified, either with or without the
       /dev/ prefix. To set the tty to use without enabling the debug shell, the systemd.default_debug_tty=
       option can be used which also takes a tty with or without the /dev/ prefix. Note that the shell may also
       be turned on persistently by enabling it with systemctl(1)'s enable command.  rd.systemd.debug_shell is
       honored only by initial RAM disk (initrd) while systemd.debug_shell is honored only in the main system.

       systemd-debug-generator implements systemd.generator(7).

       systemd-debug-generator - Generator for enabling a runtime debug shell and masking specific units at boot

systemd(1), systemctl(1), kernel-command-line(7)

systemd 257.7                                                                         SYSTEMD-DEBUG-GENERATOR(8)

/usr/lib/systemd/system-generators/systemd-debug-generator

systemd.extra-unit.*
           Credentials prefixed with "systemd.extra-unit."  specify additional units to add to the final system.
           Note that these additional units are added to both the initrd and the final system.
           ConditionPathExists=!/etc/initrd-release can be used to make sure the unit is conditioned out in the
           initrd. Note that this can also be used to mask units, by simply specifying an empty value.

           Added in version 256.

       systemd.unit-dropin.*
           Credentials prefixed with "systemd.unit-dropin."  add drop-ins for the corresponding units in the
           final system. Each credential must be suffixed with the full unit name including the unit extension.
           Its contents must be a valid unit drop-in file. Optionally, the unit name may be followed with "~",
           followed by the drop-in name without the ".conf" suffix. If not specified, the name of the generated
           drop-in will be "50-credential.conf". Note that these additional drop-ins are added to both the
           initrd and the final system.

           Added in version 256.