CONFIG_CAVIUM_RESERVE32 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Memory to reserve for user processes shared region (MB)

configname: CONFIG_CAVIUM_RESERVE32

Linux Kernel Configuration
└─>Memory to reserve for user processes shared region (MB)
In linux kernel since version 6 (release Date: 2022-10-02)  
Reserve a shared memory region for user processes to use for hardware
memory buffers. This is required for 32bit applications to be able to
send and receive packets directly. Applications access this memory by
memory mapping /dev/mem for the addresses in /proc/octeon_info. For
optimal performance with HugeTLBs, keep this size an even number of
megabytes.