If specified, z/VM IUCV HVC accepts connections
from listed z/VM user IDs only.
+ keep_bootcon [KNL]
+ Do not unregister boot console at start. This is only
+ useful for debugging when something happens in the window
+ between unregistering the boot console and initializing
+ the real console.
+
i2c_bus= [HW] Override the default board specific I2C bus speed
or register an additional I2C bus that is not
registered from board initialization code.