CONFIG_BLACKFIN is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin

CONFIG_BLACKFIN (not configurable)

configname: CONFIG_BLACKFIN

Blackfin Kernel Configuration
└─>BLACKFIN
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
selects

CONFIG_HAVE_ARCH_KGDB
CONFIG_HAVE_ARCH_TRACEHOOK
CONFIG_HAVE_DYNAMIC_FTRACE
CONFIG_HAVE_FTRACE_MCOUNT_RECORD
CONFIG_HAVE_FUNCTION_GRAPH_TRACER
CONFIG_HAVE_FUNCTION_TRACER
CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
CONFIG_HAVE_IDE
CONFIG_HAVE_IRQ_WORK
CONFIG_HAVE_KERNEL_GZIP
CONFIG_HAVE_KERNEL_BZIP2
CONFIG_HAVE_KERNEL_LZMA
CONFIG_HAVE_KERNEL_LZO
CONFIG_HAVE_OPROFILE
CONFIG_HAVE_PERF_EVENTS
CONFIG_ARCH_WANT_OPTIONAL_GPIOLIB
CONFIG_HAVE_GENERIC_HARDIRQS
CONFIG_GENERIC_ATOMIC64
CONFIG_GENERIC_IRQ_PROBE
CONFIG_IRQ_PER_CPU