CONFIG_X86_INTEL_MPX is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT
default or selected kernelversion does not have config value CONFIG_X86_INTEL_MPX.
Result is shown for kernelversion 6.7.7

Intel MPX (Memory Protection Extensions)

modulename: mpx.ko

configname: CONFIG_X86_INTEL_MPX

Linux Kernel Configuration
└─>Processor type and features
└─>Intel MPX (Memory Protection Extensions)
In linux kernel since version 3.10 (release Date: 2013-06-30)  
MPX provides hardware features that can be used in
conjunction with compiler-instrumented code to check
memory references. It is designed to detect buffer
overflow or underflow bugs.

This option enables running applications which are
instrumented or otherwise use MPX. It does not use MPX
itself inside the kernel or to protect the kernel
against bad memory references.

Enabling this option will make the kernel larger:
~8k of kernel text and 36 bytes of data on a 64-bit
defconfig. It adds a long to the 'mm_struct' which
will increase the kernel memory overhead of each
process and adds some branches to paths used during
exec() and munmap().

For details, see