Re: [Qemu-devel] KVM call for agenda for 2016-02-16

[Christian Borntraeger]

So my quick and dirty summary of CPU as _I_ understand it
(and I only have some part time bandwidth at the moment for that)

x86 has cpu hotplug. Some history
qemu-kvm had cpu_set in the past
qemu has cpu_add for a while now
libvirt code uses cpu_add cross-platform out of the box

proposal to use device_add. Currently this has the following issues that
we need to discuss:
- will require capability checking and dual code in libvirt (and libvirt 
updates)
- Power has some constraints that are hard to model with just device add
        - David Gibson proposes a two layer interface
                - low level: device add cpu-package
                - high level
- David Hildenbrand has some concerns regarding CPU models (with base model + 
feature
  on/off), as device_add needs instantiatable type
- devel_del: s390 has no interface for cpu removal (Matts latest patches reset 
the 
machine just like z/VM - until we have some interface)
- anything else? (cpu hotplug on ARM or MIPS?)

Would be good to use todays call to have a plan how to finish things soon.
(maybe even for 2.6)

Christian