I've read a lot of stuff about undervolting and to proceed I need a custom kernel with voltage control enabled.
I can't find any reliable kernel, Nexus 4 is pretty old, there aren't many kernels compatible with android 7.1 out there and given that I only want to undervolt, I don't like the idea of using a custom kernel with unneeded (for me) customisations other than voltage control.
1) Can I just change some parameters in my Lineage OS kernel in order to allow undervolt?
2) Which are these parameters?
3) Should I apply this customisations after every update?
4) Is there any way to choose which kernel pick up at boot? Like with GRUB in many Linux distro.