On Mon, Sep 05, 2016 at 06:24:48PM +0200, Laszlo Ersek wrote: > On 09/01/16 15:22, Marcel Apfelbaum wrote: > > +2.3 PCI only hierarchy > > +====================== > > +Legacy PCI devices can be plugged into pcie.0 as Integrated Devices or > > +into DMI-PCI bridge. PCI-PCI bridges can be plugged into DMI-PCI bridges > > +and can be nested until a depth of 6-7. DMI-BRIDGES should be plugged > > +only into pcie.0 bus. > > + > > + pcie.0 bus > > + ---------------------------------------------- > > + | | > > + ----------- ------------------ > > + | PCI Dev | | DMI-PCI BRIDGE | > > + ---------- ------------------ > > + | | > > + ----------- ------------------ > > + | PCI Dev | | PCI-PCI Bridge | > > + ----------- ------------------ > > + | | > > + ----------- ----------- > > + | PCI Dev | | PCI Dev | > > + ----------- ----------- > > Works for me, but I would again elaborate a little bit on keeping the > hierarchy flat. > > First, in order to preserve compatibility with libvirt's current > behavior, let's not plug a PCI device directly in to the DMI-PCI bridge, > even if that's possible otherwise. Let's just say > > - there should be at most one DMI-PCI bridge (if a legacy PCI hierarchy > is required),
Why do you suggest this ? If the guest has multiple NUMA nodes and you're creating a PXB for each NUMA node, then it looks valid to want to have a DMI-PCI bridge attached to each PXB, so you can have legacy PCI devices on each NUMA node, instead of putting them all on the PCI bridge without NUMA affinity. > - only PCI-PCI bridges should be plugged into the DMI-PCI bridge, What's the rational for that, as opposed to plugging devices directly into the DMI-PCI bridge which seems to work ? Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|
