CONFIG_OPENRISC_HAVE_INST_FF1 is not available for thedefaultarchitecture x86.
Result is shown for architecture openrisc
Have instruction l.ff1
configname: CONFIG_OPENRISC_HAVE_INST_FF1
Linux Kernel Configuration
└─>Processor type and features
└─>Class II Instructions
└─>Have instruction l.ff1
In linux kernel since version 3.1 (release Date: 2011-10-24)
Select this if your implementation has the Class II instruction l.ff1