One involves reverting code that improved the accuracy of the displayed CPU frequency on modern, dynamically-clocked processors in /proc/cpuinfo. It worked as intended in most cases, but there were lingering issues with overhead on machines with tens or hundreds of CPU cores. There’s a plan to bring the feature back, but not anytime soon.
Another change is AMD Secure Memory Encryption, an optional feature that can be used to protect the contents of DRAM from physical attacks on the system, and a new “unwinder” which prints the list of functions (i.e.. stack trace, callgraph, call stack) that have been executed before reaching a determinate point of the code. Linux already had an unwinder, but it wasn’t as efficient as ORC unwinder, which doesn’t need to insert code anywhere and so doesn’t affect text size or runtime performance.
Other changes in version 4.14 of the Linux kernel include bigger memory limits, since the original x86-64 was limited by 4-level paging to 256 TiB of virtual address space and 64 TiB of physical address space.
