CONFIG_RISCV is not available for thedefaultarchitecture x86.
Result is shown for architecture riscv

CONFIG_RISCV (not configurable)

configname: CONFIG_RISCV

Linux Kernel Configuration
└─>RISCV
In linux kernel since version 3.10 (release Date: 2013-06-30)  
selects
CONFIG_ACPI_GENERIC_GSI
CONFIG_ACPI_REDUCED_HARDWARE_ONLY
CONFIG_ARCH_DMA_DEFAULT_COHERENT
CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK
CONFIG_ARCH_ENABLE_THP_MIGRATION
CONFIG_ARCH_HAS_BINFMT_FLAT
CONFIG_ARCH_HAS_CURRENT_STACK_POINTER
CONFIG_ARCH_HAS_DEBUG_VIRTUAL
CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE
CONFIG_ARCH_HAS_DEBUG_WX
CONFIG_ARCH_HAS_FORTIFY_SOURCE
CONFIG_ARCH_HAS_GCOV_PROFILE_ALL
CONFIG_ARCH_HAS_GIGANTIC_PAGE
CONFIG_ARCH_HAS_KCOV
CONFIG_ARCH_HAS_MMIOWB
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
CONFIG_ARCH_HAS_PMEM_API
CONFIG_ARCH_HAS_PTE_SPECIAL
CONFIG_ARCH_HAS_SET_DIRECT_MAP
CONFIG_ARCH_HAS_SET_MEMORY
CONFIG_ARCH_HAS_STRICT_KERNEL_RWX
CONFIG_ARCH_HAS_STRICT_MODULE_RWX
CONFIG_ARCH_HAS_SYSCALL_WRAPPER
CONFIG_ARCH_HAS_TICK_BROADCAST
CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL
CONFIG_ARCH_HAS_VDSO_DATA
CONFIG_ARCH_OPTIONAL_KERNEL_RWX
CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
CONFIG_ARCH_STACKWALK
CONFIG_ARCH_SUPPORTS_ATOMIC_RMW
CONFIG_ARCH_SUPPORTS_CFI_CLANG
CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
CONFIG_ARCH_SUPPORTS_HUGETLBFS
CONFIG_ARCH_SUPPORTS_PAGE_TABLE_CHECK
CONFIG_ARCH_SUPPORTS_PER_VMA_LOCK
CONFIG_ARCH_USE_MEMTEST
CONFIG_ARCH_USE_QUEUED_RWLOCKS
CONFIG_ARCH_USES_CFI_TRAPS
CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
CONFIG_ARCH_WANT_FRAME_POINTERS
CONFIG_ARCH_WANT_GENERAL_HUGETLB
CONFIG_ARCH_WANT_HUGE_PMD_SHARE
CONFIG_ARCH_WANT_LD_ORPHAN_WARN
CONFIG_ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
CONFIG_ARCH_WANTS_THP_SWAP
CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
CONFIG_BUILDTIME_TABLE_SORT
CONFIG_CLINT_TIMER
CONFIG_CLONE_BACKWARDS
CONFIG_COMMON_CLK
CONFIG_CPU_PM
CONFIG_EDAC_SUPPORT
CONFIG_FRAME_POINTER
CONFIG_GENERIC_ARCH_TOPOLOGY
CONFIG_GENERIC_ATOMIC64
CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
CONFIG_GENERIC_EARLY_IOREMAP
CONFIG_GENERIC_ENTRY
CONFIG_GENERIC_GETTIMEOFDAY
CONFIG_GENERIC_IDLE_POLL_SETUP
CONFIG_GENERIC_IOREMAP
CONFIG_GENERIC_IRQ_IPI
CONFIG_GENERIC_IRQ_IPI_MUX
CONFIG_GENERIC_IRQ_MULTI_HANDLER
CONFIG_GENERIC_IRQ_SHOW
CONFIG_GENERIC_IRQ_SHOW_LEVEL
CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED
CONFIG_GENERIC_PCI_IOMAP
CONFIG_GENERIC_PTDUMP
CONFIG_GENERIC_SCHED_CLOCK
CONFIG_GENERIC_SMP_IDLE_THREAD
CONFIG_GENERIC_TIME_VSYSCALL
CONFIG_GENERIC_VDSO_TIME_NS
CONFIG_HARDIRQS_SW_RESEND
CONFIG_HAS_IOPORT
CONFIG_HAVE_ARCH_AUDITSYSCALL
CONFIG_HAVE_ARCH_HUGE_VMALLOC
CONFIG_HAVE_ARCH_HUGE_VMAP
CONFIG_HAVE_ARCH_JUMP_LABEL
CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
CONFIG_HAVE_ARCH_KASAN
CONFIG_HAVE_ARCH_KASAN_VMALLOC
CONFIG_HAVE_ARCH_KFENCE
CONFIG_HAVE_ARCH_KGDB
CONFIG_HAVE_ARCH_KGDB_QXFER_PKT
CONFIG_HAVE_ARCH_MMAP_RND_BITS
CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
CONFIG_HAVE_ARCH_SECCOMP_FILTER
CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
CONFIG_HAVE_ARCH_TRACEHOOK
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE
CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
CONFIG_HAVE_ARCH_VMAP_STACK
CONFIG_HAVE_ASM_MODVERSIONS
CONFIG_HAVE_CONTEXT_TRACKING_USER
CONFIG_HAVE_DEBUG_KMEMLEAK
CONFIG_HAVE_DMA_CONTIGUOUS
CONFIG_HAVE_DYNAMIC_FTRACE
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS
CONFIG_HAVE_FTRACE_MCOUNT_RECORD
CONFIG_HAVE_FUNCTION_GRAPH_TRACER
CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
CONFIG_HAVE_FUNCTION_TRACER
CONFIG_HAVE_EBPF_JIT
CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
CONFIG_HAVE_FUNCTION_ERROR_INJECTION
CONFIG_HAVE_GCC_PLUGINS
CONFIG_HAVE_GENERIC_VDSO
CONFIG_HAVE_IRQ_TIME_ACCOUNTING
CONFIG_HAVE_KPROBES
CONFIG_HAVE_KPROBES_ON_FTRACE
CONFIG_HAVE_KRETPROBES
CONFIG_HAVE_LD_DEAD_CODE_DATA_ELIMINATION
CONFIG_HAVE_MOVE_PMD
CONFIG_HAVE_MOVE_PUD
CONFIG_HAVE_PCI
CONFIG_HAVE_PERF_EVENTS
CONFIG_HAVE_PERF_REGS
CONFIG_HAVE_PERF_USER_STACK_DUMP
CONFIG_HAVE_POSIX_CPU_TIMERS_TASK_WORK
CONFIG_HAVE_PREEMPT_DYNAMIC_KEY
CONFIG_HAVE_REGS_AND_STACK_ACCESS_API
CONFIG_HAVE_RETHOOK
CONFIG_HAVE_RSEQ
CONFIG_HAVE_STACKPROTECTOR
CONFIG_HAVE_SYSCALL_TRACEPOINTS
CONFIG_HOTPLUG_CORE_SYNC_DEAD
CONFIG_IRQ_DOMAIN
CONFIG_IRQ_FORCED_THREADING
CONFIG_KASAN_VMALLOC
CONFIG_LOCK_MM_AND_FIND_VMA
CONFIG_MODULES_USE_ELF_RELA
CONFIG_MODULE_SECTIONS
CONFIG_OF
CONFIG_OF_EARLY_FLATTREE
CONFIG_OF_IRQ
CONFIG_PCI_DOMAINS_GENERIC
CONFIG_PCI_MSI
CONFIG_RISCV_ALTERNATIVE
CONFIG_RISCV_INTC
CONFIG_RISCV_TIMER
CONFIG_SIFIVE_PLIC
CONFIG_SPARSE_IRQ
CONFIG_SYSCTL_EXCEPTION_TRACE
CONFIG_THREAD_INFO_IN_TASK
CONFIG_TRACE_IRQFLAGS_SUPPORT
CONFIG_UACCESS_MEMCPY
CONFIG_ZONE_DMA32