On Fri, 9 Feb 2018 15:50:00 +0100 Viktor Mihajlovski <mihaj...@linux.vnet.ibm.com> wrote:
> On 09.02.2018 15:27, Eduardo Habkost wrote: > [...] > >> I'm keeping it mainly for s390. Viktor, libvirt is still using > >> this field in s390, no? > >> > >> Dropping halted and having management software still using query-cpus > >> because of halted would be a total failure of query-cpus-fast. > > > > If I understood correctly, the CpuInfoS390::cpu_state field added > > by Viktor in another patch[1] would replace "halted" for the s390 > > case. > Right, CPUState.halted is derived from CPUS390XState.cpu_state on s390: > A cpu_state of CPU_STATE_STOPPED or CPU_STATE_CHECK_STOPPED results in > halted = true. This derivation can be done by libvirt for s390. > > > > I'm assuming QEMU will be able to return that field without > > interrupting the VCPUs. Viktor, is that correct? > > > > [1] https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg02032.html > > > That's correct. > >> > >>>> Also, the code that sets/clears cpu->halted is target-specific, > >>>> so I wouldn't be so sure that simply checking for > >>>> !kvm_irqchip_in_kernel() is enough on all targets. > >> > >> I checked the code and had the impression it was enough, but > >> I don't have experience with other archs. So, would be nice > >> if other archs maintainers could review this. I'll try to ping them. > > > > I think we need to take a step back and rethink: > > > > 1) What the field is supposed to mean? The semantics of "halted" > > are completely unclear. What exactly we want to communicate > > to libvirt/management? > > 2) On which cases the information (whatever it means) is really > > useful/important? If you are excluding cases with in-kernel > > irqchip, you are already excluding most users. > > > > > Given that nobody (including myself) sees a need for halted we can > remove it for the fast version of query-cpus without surprising anyone. > [...] My conclusion too, I'll drop it.
