I can confirm now, that that kernel breaks both a desktop (an ThinkPad T440s i5) and a headless server (i3930) setup. For the server the attached .config works fine but switching from CONFIG_GENERIC_CPU to CONFIG_MCORE2 legt them hang at boot w/op any messages. Similar picture at the desktop. Both are stable Gentoo Linux hardened systems.
This issue seems to exist in mainline too, probably visible with d120cd749 (stable) and 9aaefe7b59 (upstream).