After running further tests today, I think this is in fact *not* related to gcc but to the kernel itself.
I tested all 6.2.1-X versions as well as gcc-5 (5.4.1-3) and all the kernels fail to boot (balck screen just after grub and nothing in the logs). A few days ago (beginning of this week, I was able to compile the 4.9-rc6+ kernel fine (with gcc-6 6.2.1-4) so something must have changed in the kernel itself (or elsewhere on the system?). I am not able to bisect now, but at least this seems to clear gcc from being the main culprit. Best regards Damien
