On Wed, Oct 02, 2013 at 10:53:07AM +0200, Paolo Bonzini wrote: > Il 25/09/2013 10:59, Michael S. Tsirkin ha scritto: > >> > I couldn't find on PCIe spec any mention that "Root Complex Integrated EndPoint" > >> > must be PCIe. But, from spec 1.3.2.3: > >> > - A Root Complex Integrated Endpoint must not require I/O resources claimed through BAR(s). > >> > - A Root Complex Integrated Endpoint must not generate I/O Requests. > >> > - A Root Complex Integrated Endpoint is required to support MSI or MSI-X or both if an > >> > interrupt resource is requested. > > Heh PCI-SIG keeps fighting against legacy interrupts and IO. > > But lots of hardware happily ignores these rules. > > And the reason is simple: software does not enforce them. > > I think it's "must not require", not "must not have". So it's the usual > rule that applies to PCIe device, i.e. that they should work even if the > OS doesn't enable the I/O BARs. I agree, thanks for pointing this out. Seems to still apply to the MSI rule. > Then I have no idea what the I/O BAR in i915 is for, and whether the > device can be used without that BAR. > > Paolo -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list