F31 & cgroups v2

It looks like the change request was accepted for f31 to move to the unified hierarchy by default. https://pagure.io/fesco/issue/2177 This is awesome, except that runc doesn’t really have proper support for cgroups v2 yet. I can envision the following options but I’m sure others probably have better ideas here.

1). Boot in mixed mode w/ both hierarchies mounted. This is what Fedora has been doing and would offer the best support for runC out of the box.

2). Default to crun in Silverblue. crun does have preliminary support for cgroups v2 and I’ve been using it on my daily driver for a while now. This seems like a good path for SB, but I haven’t done much testing with toolbox.

Kubernetes is the real blocker for cgroups v2, and this is why it makes sense for CoreOS to stay on v1 to accommodate that use case. We don’t have that with SB, so I’m hoping it’s less disruptive and we can move to v2 sooner. Any thoughts?