So, I made the change to "kvariant", and installed the kernel, but something broke and I had to manually restore the /boot partition with files from another Pi.

If anyone needs to fix his install, I recommend to

yum reinstall raspberrypi2-kernel-firmware raspberrypi2-firmware

and

yum reinstall raspberrypi2-kernel-4.9.64

Another thing I noticed is that the config.txt supplied by the CenOS distro sets

arm_freq=700

This is disasterous if you are running an RPI3 :) Here is the setup I'm using for my little RPI3 Samba Domain controllers:

---

hdmi_safe=1

#overclock rpi3 moderately

#https://github.com/retropie/retropie-setup/wiki/Overclocking

total_mem=1024

arm_freq=1300

gpu_freq=500

core_freq=500

sdram_freq=500

sdram_schmoo=0x02000020

over_voltage=2

sdram_over_voltage=2

#minimum video ram

gpu_mem=16

#disable wifi and bluetooth

dtoverlay=pi3-disable-wifi

dtoverlay=pi3-disable-bt

#fast sd card, only for UHS cards

#(may prevent booting, have tools on hand to revert this)

#dtparam=sd_overclock=100

#boot_delay=2

Kv,

Kristján Valur Jónsson, RVX