CONFIG_ARM_ERRATA_857271 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

ARM errata: A12: CPU might deadlock under some very rare internal conditions

configname: CONFIG_ARM_ERRATA_857271

Linux Kernel Configuration
└─>System Type
└─>ARM errata: A12: CPU might deadlock under some very rare internal conditions
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This option enables the workaround for the 857271 Cortex-A12
(all revs) erratum. Under very rare timing conditions, the CPU might
hang. The workaround is expected to have a < 1% performance impact.

depends
CONFIG_CPU_V7