Linux kernel version 6.9 introduces FRED (Flexible Return and Event Delivery system) on x86_64, adding 16 bytes to task kernel stack areas and affecting eBPF development. The feature aims to optimize CPU privilege level switching on Intel CPUs, requiring developers to adjust their kernel stack and pt_regs lookup code accordingly.

https://tanelpoder.com/posts/ebpf-pt-regs-error-on-linux-blame-fred/

#linuxkernel #ebpf #fred #intelcpu #systemarchitecture