On Tue, May 22, 2018 at 03:36:59PM -0600, Alex Williamson wrote: > On Tue, 22 May 2018 23:58:30 +0300 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > It's not hard to think of a use-case where >256 devices > > are helpful, for example a nested virt scenario where > > each device is passed on to a different nested guest. > > > > But I think the main feature this is needed for is numa modeling. > > Guests seem to assume a numa node per PCI root, ergo we need more PCI > > roots. > > But even if we have NUMA affinity per PCI host bridge, a PCI host > bridge does not necessarily imply a new PCIe domain.
What are you calling a PCIe domain? > Nearly any Intel > multi-socket system proves this. Don't get me wrong, I'd like to see > PCIe domain support and I'm surprised edk2 is so far from supporting > it, but other than >256 hotpluggable slots, I'm having trouble coming > up with use cases. Maybe hotpluggable PCI root hierarchies are easier > with separate domains? Thanks, > > Alex