Re: [Xen-devel] [PATCH 2/3] qemu-xen-trad: Correctly expose PCH ISA bridge for IGD passthrough

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

On Fri, Feb 8, 2013 at 7:48 PM, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Fri, 8 Feb 2013, Jan Beulich wrote:
>> >>> On 08.02.13 at 12:30, Stefano Stabellini 
>> >>> <stefano.stabellini@xxxxxxxxxxxxx>
>> wrote:
>> > On Thu, 7 Feb 2013, G.R. wrote:
>> >> >
>> >> > For one I wonder whether this is really _always_ correct. I.e.
>> >> > the device at 00:1f.0 always being an ISA bridge. Wouldn't it
>> >> > be better to mirror whatever the host device says?
>> >> >
>> >> >From the Intel driver code, it's looking for an intel ISA bridge.
>> >> So your question would be should it be always at 00:1f.0.
>> >> So far it seems that it is.
>> >>
>> >> > And then I don't see why you need to open code all of
>> >> > pci_bridge_init() instead of just overriding the class value after
>> >> > you called that function (or, if the order of events for some
>> >> > reason matters, adding another parameter to the function).
>> >>
>> >> Stefano, could you comment? It's your code after all.
>> >
>> > It's not trivial because PCIBus is defined in hw/pci.c, so you can't
>> > dereference members of PCIBus from hw/pt-graphics.c.
>>
>> But the patch makes it so the structure itself becomes public?
>> What problem do you see?
>
> QEMU's include chain can be devious at times but I have no objections in
> making PCIBus public.

Are you talking about making PCIBus public (to hw/pci.h) and change
the code to something like this:

    if (vid == PCI_VENDOR_ID_INTEL) {
        PCIBus *s = pci_bridge_init(bus, PCI_DEVFN(0x1f, 0), vid, did, rid,
                                       pch_map_irq, "intel_bridge_1f");

        pci_config_set_class(s->parent_dev.config, PCI_CLASS_BRIDGE_ISA);
        s->parent_dev.config[PCI_HEADER_TYPE] = 0x80;
    }

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