On Tue, 4 Dec 2018 at 19:05, Eduardo Habkost <ehabk...@redhat.com> wrote: > On Tue, Dec 04, 2018 at 06:24:19PM +0000, Peter Maydell wrote: > > A cluster is a group of CPUs which are all identical and have > > the same view of the rest of the system.
> With that definition in mind, why can't QEMU cluster CPUs > automatically by looking at CPU models and address space objects? That sounds like it is in theory feasible and in practice quite tricky. You would have to look not just at the CPU model name but also introspect all its properties for ones which change features of the CPU and are set differently on different CPUs (and I don't think there's any way to automatically tell which properties are ones which make the CPU different for which-cluster purposes and which aren't). And if we automatically checked whether address space objects were the same it would rule out implementing devices with per-cpu banked memory mapped registers by mapping different things into the AS for each CPU (though that's a hypothetical at the moment -- I've thought about implementing stuff that way but we tend to implement that sort of thing by looking at current_cpu->cpu_index at the moment). thanks -- PMM
