Well, it ran a couple of days before freezing again. That was with
idle=nomwait (I think that was the specific mwait kernel command line
Debian (and hence Devuan) doesn't have CONFIG_RCU_NOCB_CPU (or similar)
set, so adding rcu_nocbs=0-11 does nothing (no code to look at that
option in the kernel, as near as I can tell). But, I am trying it
anyway, maybe my data is out of date. There is something else a person
can specify, and that is processor.max_cstate=5 (which would keep it
from getting to state c6). This has a small effect on reaching the
highest clock frequencies for the CPU.
Debian bug 804857 has the last entry being a request to add some of
this functionality, due to this CPU freezing problem. That was in
February (no response).
Someone has built a web page which goes through all the fairly recent
steps to compile a kernel on a Debian type system. I didn't note the
page however. Running make menuconfig still requires tooooooo much
knowledge of just about every trivial factor in PCs, and hence takes a
long time to run.