Re: [libvirt] [RFC] kvm: x86: export vCPU halted state to sysfs

>> Markus, Eric: from the QAPI point of view, is it OK to remove >> fields between QEMU versions, as long as we follow our >> deprecation policy? > > I would expect that to not be OK. A fully backwards compatible way to > deal with this would just be to add a flag to the query-cpus command > eg something like > > query-cpus arch-specific=false > > to turn off all this arch specific state, and just report the cheap > generic info. If it defaults to arch-specific=true when omitted, then > there's no compat problems. This would work, too. I would name it "full-state", "extended-state" or something similar, though. Not all arch-specific data is expensive to fetch, and not all non-arch-specific data is unexpensive. But I'd like to confirm if it's OK to make existing non-optional struct fields optional in the QAPI schema. Markus, Eric?