Re: [libvirt] [PATCH] qemu: Permit PCI-free aarch64 mach-virt guests

On Fri, 2016-06-17 at 12:01 -0400, Laine Stump wrote: > On 06/17/2016 11:46 AM, Martin Kletzander wrote: > > On Fri, Jun 17, 2016 at 11:36:05AM -0400, Laine Stump wrote: > > > On 06/17/2016 08:43 AM, Andrea Bolognani wrote: > > > >             * other than the pcie-root. This is so that there will be  > > > > hot-pluggable > > > > -         * PCI slots available > > > > +         * PCI slots available. > > > > +         * > > > > +         * We skip this step for aarch64 mach-virt guests, where we  > > > > want to > > > > +         * be able to have a pure virtio-mmio topology > > > >             */ > > > >            if (virDomainControllerFind(def,  > > > > VIR_DOMAIN_CONTROLLER_TYPE_PCI, 1) < 0 && > > > > +            !qemuDomainMachineIsVirt(def) && > > >   > > > You're assuming that the only virt* machinetypes will be aarch64, which > > > may be reasonable now, but not in the future (periodically someone from > > > qemu will mention the idea of a "virt" machinetype for x86, which is > > > legacy-free and accepts only virtio devices). Wouldn't a more specific > > > comparison be better here (and in the other places in this patch)? > >   > > Just my $.02 here, but since our qemuDomainMachineIsVirt() is made > > specifically for aarch64 arches, I think the right thing to do would be > > just add architecture check into that function as using it throughout > > the codebase ought to actually be what all the callers want. >   > Sure, a single function would be great. Its name should reflect that it  > is for *aarch64* virt machines though (in anticipation of other arches  > getting a virt machinetype). I think we can stick with qemuDomainMachineIsVirt() for now, and create per-arch variants if and when another architecture grows its own virt machine type. But I'm totally for moving the architecture checks inside the function; in fact, I'd like to do the same for pSeries guests. I'll work on it next week.