On Wed, 23 May 2018 00:44:22 +0300 "Michael S. Tsirkin" <m...@redhat.com> wrote:
> 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? Domain/segment 0000:00:00.0 ^^^^ This Isn't that the only reason we'd need a new MCFG section and the reason we're limited to 256 buses? Thanks, Alex
