On Wed, Nov 08, 2017 at 04:02:22PM -0800, Andi Kleen wrote:

There's also older patches to enable single-pass-linking for kallsyms,
which is extremly useful for LTO build performance.

Excellent, can you point me to the patch in question?

I worked around the build performance problem by reusing vmlinux.o for
kallsyms instead of linking all bitcode again in each step. I'm not sure
if this is feasible with gcc.

Sami