Flexible Return and Event Delivery

modulename: fred.ko

and/or

entry_64_fred.ko

configname: CONFIG_X86_FRED

Linux Kernel Configuration
└─>Processor type and features
└─>Flexible Return and Event Delivery
In linux kernel since version 4.19.314 (release Date: 2024-05-17)  
When enabled, try to use Flexible Return and Event Delivery
instead of the legacy SYSCALL/SYSENTER/IDT architecture for
ring transitions and exception/interrupt handling if the
system supports it.

source code:
depends
CONFIG_X86_64

is depended by
CONFIG_KVM_INTEL