Comment 27 for bug 1828495

Hello quanxian,

Could you clarify exactly what is the expected behaviour and what wasn't achieved ?
We'd like to understand better the requirements, rather than having patches pointed out only. Mainly because there are some rules we usually follow for already released versions and some of them might be discussable and some might not.

Based on the thread you pointed out:

* Patch "i386: Infrastructure for versioned CPU models" was
  rewritten and split in two:
  * i386: Register versioned CPU models
  * i386: Make unversioned CPU models be aliases
* -IBRS, -noTSX, -IBPB CPU models are now aliases
* Enable rdctl-no, ibrs-all, skip-l1dfl-vmentry in
* New patch added:
  * i386: Get model-id from CPU object on "-cpu help"

Are you looking for the CPU versioning feature ? (Rather than only having stepping increased/decreased ?). Are you looking for Cascadelake-server-v2 CPU type ? Or on having, by default, the CPU flags rdctl-no, ibrs-all, skip-l1dfl-vmentry enabled ?

I'm asking you this because, for backports, we are looking forward to enabling those features ad-hoc, and not by default (as they seem to be in the PPA). Specially because we have to guarantee compatibility in between QEMU diff versions migrations. This has been done already before, for some other requested features.

Thank you very much in advance for your feedback.