Since the version 4.9 update of gcc, I believe that an option hardcoded in the kernel's Processor type and features --> Processor family is now outdated. It is the selection for the Intel Atom. This is linked to -march=atom in several files including arch/x86/Makefile_32.cpu and arch/x86/Makefile but I believe that gcc has depracated this particular switch changing it to march=bonnell/mtune=bonnell or the like. See the following in the gcc 4.9 release notes for more. https://gcc.gnu.org/gcc-4.9/changes.html
6 months an no activity. Bumping for coverage.
https://github.com/graysky2/kernel_gcc_patch Kernel maintainers should use enable_additional_cpu_optimizations_for_gcc_v4.9+_kernel_v4.13+.patch. There is no sense that thousands of other kernel developers must use this patch.