On Tue, Oct 18, 2016 at 06:07:49PM +0100, Peter Maydell wrote: > On 18 October 2016 at 17:22, Andrew Jones <drjo...@redhat.com> wrote: > > I'll note that it's > > accepted to reach into machine state through current_machine from > > the machine's devices. > > That doesn't sound like a great idea to me -- where do we > do it? A quick grep for uses of current_machine in hw/ shows only > hw/ppc/spapr_rtas.c, which is a bit of a weirdo thing because > it's the implementation of a bunch of hypercalls, not an actual > device. > > We have lots of code currently in devices that looks at bits > of overall state that it should ideally not (but which it can > because we have a lot of global variables). In an ideal world > we'd clean these up so that the devices were initialized with > suitable properties instead to tell them about this global state. > > >> > I considered that, but if we un-property ARMCPU->mp_affinity, then where > >> > can it be initialized to "MP_AFFINITY_INVALID", which would be ff000000? > >> > >> Property defaults are normally initialized on instance_init. > > > > OK, so after this series goes through we can un-property mp_affinity and > > add an mp_affinity initialization back to arm_cpu_initfn, but one that > > only sets the initial invalid value. > > Note that mp_affinity is a bit awkward because for KVM we can't > get the right values out of the kernel until quite late (when > kvm_init_vcpu() is called). > > Why do you want to un-property mp_affinity? Eventually it would > be nice for the machine model to be able to use it to set up > a specific NUMA configuration.
I thought about that, but I think we'll want to specify machine properties; nr_sockets, nr_cores, nr_threads and use the -device command line for the cpu to specify which socket, which core, which thread it is. This would be consistent with other architectures and easily map to the MPIDR & cpu topology hardware descriptions. Anyway, atm, I don't know of any reason to have the property user- settable, so it seems safest to keep it hidden until we decide. Thanks, drew
