On Mon, Feb 29, 2016 at 04:42:58PM +0100, Igor Mammedov wrote: [...] > > > > > i.e. completely split interface from how boards internally implement > > > > > CPU hotplug. > > > > > > > > A QOM-based interface may still split the interface from how > > > > boards internally implement CPU hotplug. They don't need to > > > > affect the device tree of the machine, we just need to create QOM > > > > objects or links at predictable paths, that implement certain > > > > interfaces. > > > Beside of not being able to reach consensus for a long time, > > > I'm fine with isolated QOM interface if it allow us to move forward. > > > However static QMP/QAPI interface seems to be better describing and > > > has better documentation vs current very flexible poorly self-describing > > > QOM. > > > > You have a good point: QMP is more stable and better documented. > > QOM is easier for making experiments, and I would really like to > > see it being used more. But if we still don't understand the > > requirements enough to design a QMP interface, we won't be able > > to implement the same functionality using QOM either. > > > > If we figure out the requirements, I believe we should be able to > > design equivalent QMP and QOM interfaces. > So not to stall CPU hotplug progress, I'd start with stable QMP query > interface for general use, leaving experimental QOM interface for later > as difficult to discover and poorly documented one from mgmt pov, > meaning mgmt would have to: > - instantiate a particular machine type to find if QOM interface is > supported, > i.e. '-machine none' won't work with it as it's board depended VS static > compile time qapi-schema in QMP case > - execute a bunch of qom-list/qom-read requests over wire to enumerate/query > objects starting at some fixed entry point (/machine/cpus) VS a single > command that does 'atomic' enumeration in QMP case.
Agreed. -- Eduardo
