CONFIG_ARM64_ERRATUM_1024718 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64

Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update

configname: CONFIG_ARM64_ERRATUM_1024718

Linux Kernel Configuration
└─>Kernel Features
└─>ARM errata workarounds via the alternatives framework
└─>Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This option adds a workaround for ARM Cortex-A55 Erratum 1024718.

Affected Cortex-A55 cores (all revisions) could cause incorrect
update of the hardware dirty bit when the DBM/AP bits are updated
without a break-before-make. The workaround is to disable the usage
of hardware DBM locally on the affected cores. CPUs not affected by
this erratum will continue to use the feature.

If unsure, say Y.