[libvirt] [PATCH v5 0/4] qemu: Allow PCI virtio on ARM "virt" machine

[Pavel Fedin]

 Hello!

> The original patches to support pcie-root severely restricted what could
> plug into what because in real hardware you can't plug a PCI device into
> a PCIe slot (physically it doesn't work)

 But how do you know whether the device is PCI or PCIe ? I don't see anything like this in the code, i see that for example "all network cards are PCI", which is, BTW, not true in the real world.

> The behavior now is that if libvirt is auto-assigning a slot for a
> device, it will put it into a hotpluggable true PCI slot, but if you
> manually assign it to a slot that is non-hotpluggable and/or PCIe, it
> will be allowed.

 But when i tried to manually assign virtio-PCI to PCIe i simply got "Device requires standard PCI slot" and that was all. I had to make patch N4 in order to overcome this.

> BTW, I'm still wondering if the arm machinetype really does support the
> supposedly Interl-x86-specific i82801b11-bridge device

 Yes, it works fine. Just devices behind it cannot get MSI-X enabled. By the way, you should be using virtio-pci with PC guests for a while, does it also suffer from this restriction there ?

> (and the new > controller devices - ioh3420 (pcie-root-port), x3130-upstream
> (pcie-switch-upstream-port), and xio3130-downstream
> (pcie-switch-downstream-port).

 Didn't try that, but don't see why they would not work. PCI is just PCI after all, everything behing the controller is pretty much standard and arch-independent.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia