CONFIG_ARM64_VA_BITS_52 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

52-bit

configname: CONFIG_ARM64_VA_BITS_52

Virtual address space size
└─>52-bit
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
Enable 52-bit virtual addressing for userspace when explicitly
requested via a hint to mmap(). The kernel will also use 52-bit
virtual addresses for its own mappings (provided HW support for
this feature is available, otherwise it reverts to 48-bit).

NOTE: Enabling 52-bit virtual addressing in conjunction with
ARMv8.3 Pointer Authentication will result in the PAC being
reduced from 7 bits to 3 bits, which may have a significant
impact on its susceptibility to brute-force attacks.

If unsure, select 48-bit virtual addressing instead.