udev.conf — Configuration for device event managing daemon
/etc/udev/udev.conf
      systemd-udevd(8)
      expects its main configuration file at
      /etc/udev/udev.conf. It consists of a set
      of variables allowing the user to override default udev
      values. All empty lines or lines beginning with '#' are
      ignored. The following variables can be set:
    
udev_log=¶The log level. Valid values are the numerical
          syslog priorities or their textual representations:
          err, info and
          debug.
children_max=¶An integer. The maximum number of events executed in parallel.
This is the same as the --children-max= option.
exec_delay=¶An integer. Delay the execution of each RUN{
          parameter by the given number of seconds. This option
          might be useful when debugging system crashes during
          coldplug caused by loading non-working kernel
          modules.program}
This is the same as the --exec-delay= option.
event_timeout=¶An integer. The number of seconds to wait for events to finish. After this time, the event will be terminated. The default is 180 seconds.
This is the same as the --event-timeout= option.
resolve_names=¶Specifies when systemd-udevd should resolve names of users and groups.  When set to
          early (the default), names will be resolved when the rules are parsed.
          When set to late, names will be resolved for every event.  When set to
          never, names will never be resolved and all devices will be owned by
          root.
This is the same as the --resolve-names= option.
timeout_signal=¶Specifies a signal that systemd-udevd will send on worker
          timeouts. Note that both workers and spawned processes will be killed using this
          signal. Defaults to SIGKILL.
      In addition, systemd-udevd can be configured
      by command line options and the kernel command line (see
      systemd-udevd(8)).