On 26/05/21 01:45, Ben Gardon wrote:
At Google we have an informal practice of adding sysctls to control some
KVM features. Usually these just act as simple "chicken bits" which
allow us to turn off a feature without having to stall a kernel rollout
if some feature causes problems. (Sysctls were used for reasons specific
to Google infrastructure, not because they're necessarily better.)
We'd like to get rid of this divergence with upstream by converting the
sysctls to writable module parameters, but I'm not sure what the general
guidance is on writable module parameters. Looking through KVM, it seems
like we have several writable parameters, but they're mostly read-only.
Sure, making them writable is okay. Most KVM parameters are read-only
because it's much simpler (the usecase for introducing them was simply
"test what would happen on old processors"). What are these features
that you'd like to control?
I also don't see central documentation of the module parameters. They're
mentioned in the documentation for other features, but don't have their
own section / file. Should they?
They probably should, yes.
Paolo
