CONFIG_CPU_UNRET_ENTRY is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT
Enable UNRET on kernel entry
configname: CONFIG_CPU_UNRET_ENTRY
Linux Kernel Configuration
└─>Mitigations for CPU vulnerabilities
└─>Enable UNRET on kernel entry
In linux kernel since version 4.14.326 (release Date: 2023-09-23)
Compile the kernel with support for the retbleed=unret mitigation.