Re: [Qemu-devel] [PATCH] pci: add standard bridge device

[Michael S. Tsirkin]

On Thu, Sep 08, 2011 at 07:03:10PM +0800, Wen Congyang wrote:
> At 09/08/2011 06:42 PM, Michael S. Tsirkin Write:
> > On Thu, Sep 08, 2011 at 05:58:12PM +0800, Wen Congyang wrote:
> >> At 09/08/2011 05:43 PM, Gerd Hoffmann Write:
> >>>   Hi,
> >>>
> >>>> I modify the code like this, and the PCI_INTERRUPT_LINE register is
> >>>> set, and I can bind
> >>>> it to uio_pci_generic:
> >>>
> >>>> --- a/src/pciinit.c
> >>>> +++ b/src/pciinit.c
> >>>> @@ -575,6 +575,8 @@ static int pci_bios_init_root_regions(u32 start,
> >>>> u32 end)
> >>>
> >>>>       pci_bios_init_bus_bases(&busses[0]);
> >>>> -    pci_bios_map_device_in_bus(0 /* host bus */);
> >>>> +    for (bus = 0; bus<= MaxPCIBus; bus++) {
> >>>> +        pci_bios_map_device_in_bus(bus /* host bus */);
> >>>
> >>> No.  pci_bios_map_device_in_bus goes down recursively when it finds a
> >>> bridge, so it should cover all devices already.
> >>
> >> Yes, pci_bios_map_device() goes down recursively.
> > 
> > The value seems to be wrong though, I think.
> > It seems to simply use the interrupt pin as array index.
> > Instead, each bridge should interrupts as follows:
> > 
> > /* Mapping mandated by PCI-to-PCI Bridge architecture specification,
> >  * revision 1.2 */
> > /* Table 9-1: Interrupt Binding for Devices Behind a Bridge */
> > static int pci_bridge_dev_map_irq_fn(PCIDevice *dev, int irq_num)
> > {
> >     return (irq_num + PCI_SLOT(dev->devfn)) % PCI_NUM_PINS;
> > }
> > 
> > until we get to the host bridge.
> 
> I use gdb to debug, and find that this function is never called.
> 
> Thanks
> Wen Congyang

No, I mean that bios must implement this logic.
You don't see it called probably because ivshmem
does not cause interrupts for you.

> > 
> > 
> >>>
> >>>> -    pci_bios_init_device_in_bus(0 /* host bus */);
> >>>> +        pci_bios_init_device_in_bus(bus /* host bus */);
> >>>> +    }
> >>>
> >>> That is correct.  Can be done easier though by just not limiting device
> >>> initialization to a specific bus like in the attached patch.  Does that
> >>> one work for you?
> >>
> >> I test it, and it works for me.
> >>
> >> Thanks
> >> Wen Congyang
> >>
> >>>
> >>> cheers,
> >>>   Gerd
> >