Comment 4 for bug 1866866

I agree on the kernel side - as already mentioned in the bug description - I've added that only for the reason of completeness, since the kernel change is affected (even if not really by the FFe).
For the kernel only one add. commit needs to land - and that is expected soon.
Hence (as of today) it looks like this is possible in time prior to the kernel freeze.

With "...it will affect s390x only" I wanted to mitigate the impact on other architectures.
There were - and there are - of course efforts to stabilize this function (across the affected components) as much as possible. Manual test builds where done by HWE as well as by IBM (based on the Ubuntu code level) and tested.
On top a PPA was requested (see above) that allows to test affected packages as they come out of the Ubuntu build systems (so no manual builds anymore).

And your assumption about the opt-in is correct.
Users are _not_ forced to use this and the defaults will not change.
In fact, it can only be an opt-in, since it requires a certain (hw) level of a system.