default or selected kernelversion does not have config value CONFIG_X86_RESERVE_LOW_64K.
Result is shown for kernelversion 5.4.229

Reserve low 64K of RAM on AMI/Phoenix BIOSen

configname: CONFIG_X86_RESERVE_LOW_64K

Linux Kernel Configuration for x86
└─>Processor type and features
└─>Reserve low 64K of RAM on AMI/Phoenix BIOSen
In linux kernel since version (release Date: 2008-10-18)  
Reserve the first 64K of physical RAM on BIOSes that are known
to potentially corrupt that memory range. A numbers of BIOSes are
known to utilize this area during suspend/resume, so it must not
be used by the kernel.

Set this to N if you are absolutely sure that you trust the BIOS
to get all its memory reservations and usages right.

If you have doubts about the BIOS (e.g. suspend/resume does not
work or there's kernel crashes after certain hardware hotplug
events) and it's not AMI or Phoenix, then you might want to enable
X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
corruption patterns.

Say Y if unsure.