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

CONFIG_RISCV_SBI (not configurable)

modulename: sbi.ko

configname: CONFIG_RISCV_SBI

Linux Kernel Configuration
└─>RISCV_SBI
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
source code:
arch/riscv/kernel/sbi.c
depends
NOT CONFIG_RISCV_M_MODE

is selected by
CONFIG_RISCV_SBI_CPUIDLE