systemd-debug-generator - Man Page

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

systemd-debug-generator is a generator that provides some debugging functionality​.

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

systemd-debug-generator understands the following kernel command line parameters:

systemd​.mask=,  rd​.systemd​.mask=

These options take a unit name as argument​. The unit specified 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​. The option prefixed with "rd​." is honored only in the initrd, while the one without prefix is only honored on the host​.

Added in version 215​.

systemd​.wants=,  rd​.systemd​.wants=

These options take a unit name as argument​. 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​. The option prefixed with "rd​." is honored only in the initrd, while the one that is not prefixed only on the host​.

Added in version 215​.

systemd​.debug_shell,  rd​.systemd​.debug_shell,  systemd​.default_debug_tty=,  rd​.systemd​.default_debug_tty=

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​. The options prefixed with "rd​." are honored only in the initrd, while the ones without prefix are only honored on the host​.

Added in version 215​.

systemd​.break=,  rd​.systemd​.break=

Takes one of pre-udev, pre-basic, pre-mount, or pre-switch-root (the default for the "rd​." option)​. It also accepts multiple values separated by comma (",")​. These options allow one to pause the boot process at a certain point and spawn a debug shell​. After exiting this shell, the system will resume booting​. The option prefixed with "rd​." is honored only in the initrd, while the one without prefix is only honored on the host​.

Table ​1. ​Available breakpoints

Breakpoints	Description	Can be used in the initrd	Can be used on the host
pre-udev	Before starting to process kernel uevents, i​.e​., before systemd-udevd​.service starts​.	✓	✓
pre-basic	Before leaving early boot and regular services start, i​.e​., before basic​.target is reached​.	✓	✓
pre-mount	Before the root filesystem is mounted, i​.e​., before sysroot​.mount starts​.	✓	✗
pre-switch-root	Before switching from the initrd to the real root​.	✓	✗

Added in version 258​.

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​.

systemd(1), systemctl(1), kernel-command-line(7), systemd.system-credentials(7), bootup(7)