Comment # 26 on bug 1011815 from Dr. Werner Fink

Not kernel as YaST can control its terminal environment by using

  klogconsole

that is

  a) set effective the log level with option -l at least during
     YaST session.

and, if available

  b) set the logging virtual console to e.g. the SUSE traditional tty10
     at least during the YaST session

also using the kernel command line option quiet could be an option.
Beside this: there exists a package syslog-service which does provide
the service unit /usr/lib/systemd/system/klog.service and therein the
ExecStart

  /bin/sh -c "test -c /dev/tty10 && /usr/sbin/klogconsole $KLOGCONSOLE_PARAMS
-r10 || :"

Also configuring and checking the current default via r/w the
/proc/sys/kernel/printk
could be an option ... see man:syslog(2)  

   /proc/sys/kernel/printk
       /proc/sys/kernel/printk is a writable file containing four integer val-
       ues that influence kernel printk() behavior when  printing  or  logging
       error messages.  The four values are:

       console_loglevel
              Only  messages  with  a  log level lower than this value will be
              printed to the console.  The default value  for  this  field  is
              DEFAULT_CONSOLE_LOGLEVEL  (7),  but it is set to 4 if the kernel
              command line contains the word "quiet", 10 if the kernel command
              line  contains  the  word "debug", and to 15 in case of a kernel
              fault (the 10 and 15 are just silly, and equivalent to 8).   The
              value  of  console_loglevel  can be set (to a value in the range
              1-8) by a syslog() call with a type of 8.

       default_message_loglevel
              This value will be used as the log level for  printk()  messages
              that  do  not have an explicit level.  Up to and including Linux
              2.6.38, the hard-coded  default  value  for  this  field  was  4
              (KERN_WARNING);  since  Linux  2.6.39,  the  default  value is a
              defined by the kernel configuration  option  CONFIG_DEFAULT_MES-
              SAGE_LOGLEVEL, which defaults to 4.

       minimum_console_loglevel
              The  value  in  this  field  is  the minimum value to which con-
              sole_loglevel can be set.

       default_console_loglevel
              This is the default value for console_loglevel.

   The log level
       Every printk() message has its own log level.  If the log level is  not
       explicitly   specified   as   part  of  the  message,  it  defaults  to
       default_message_loglevel.  The conventional meaning of the log level is
       as follows:

       Kernel constant   Level value   Meaning
       KERN_EMERG             0        System is unusable
       KERN_ALERT             1        Action must be taken immediately
       KERN_CRIT              2        Critical conditions
       KERN_ERR               3        Error conditions
       KERN_WARNING           4        Warning conditions
       KERN_NOTICE            5        Normal but significant condition
       KERN_INFO              6        Informational
       KERN_DEBUG             7        Debug-level messages

       The kernel printk() routine will print a message on the console only if
       it has a log level less than the value of console_loglevel.